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Skin infections are a common complaint in primary care and are usually considered benign. However, in both New Zealand (NZ) and international settings, these infections are becoming an increasingly significant source of childhood morbidity, with the rate of skin infections requiring hospitalisation (termed serious skin infections) steadily increasing during the last two decades.1-7In NZ, the rate of serious skin infections, doubled between 1990 and 2007.4 In 2004, a report by Hunt found the national rate of cellulitis in children was twice that of Australia and the United States of America.8Recent analyses have found that serious skin infections contribute heavily to health inequalities with the greatest hospitalisation rates observed in M ori and Pacific children.4,5,8-11 These trends are hypothesised to reflect corresponding patterns of disease in the community,8 however there are no published studies examining skin infections in the NZ primary care setting, where many patients initially present and the major burden of illness is managed. This deficit is likely due to the lack of routine primary care level surveillance for most health conditions in NZ.Hospital admissions for serious skin infections represent the tip of the iceberg in relation to the wider community burden of disease.4,8We aimed to estimate the incidence of skin infection cases in primary care in children in the Tairawhiti (Gisborne) region, describe the basic epidemiology of these infections, and compare these characteristics with serious skin infections hospitalised in the region during the same period.Methods We conducted a prospective observational analysis of skin infection cases in children seen by a cohort of general practitioners (GPs) in the Tairawhiti region. Study locationThe Tairawhiti region is a relatively isolated area of 45,000 people on the East Coast of NZs North Island. The region is unique for its large M ori population (47.3% of the total population and 58.4% of the 0-14 year old population), young age distribution (26.2% of people are aged less than 15 years),12 and high levels of deprivation (the Gisborne region has the highest proportion of the most deprived residents in the country).13 In Tairawhiti, childhood skin infections present a major challenge to both primary and secondary health services. The regions serious skin infection incidence is not only the highest in NZ,4 research presented in companion articles in this issue of the New Zealand Medical Journal has shown it is considerably greater than that expected, even after standardising for the high-risk age, ethnicity and deprivation population composition. General practitioner recruitment and data collectionThe raw data for this study were collected by prospective consultation coding by a group of Tairawhiti GPs. All GPs within the region were approached and their voluntary participation in this study sought. Out of the usual local GP population of approximately 20 full-time equivalent practitioners working in six primary practices, nine GPs from three different practices agreed to participate. During the study period, 4627 of the 18,456 (25.1%) 0-14 year olds usually resident population of the Tairawhiti region were registered in the practice populations of these GPs. Over the 10-week period, 19 May 2008 to 28 July 2008, GPs coded all incident cases of skin infection in children using the READ code system. Similar to International Classification of Disease (ICD) codes used in hospitals, READ codes are a standardised and hierarchically-arranged clinical terminology system widely used in primary care practices for coding diagnoses as well as a range of patient demographic and clinical data.14 All skin infections were included regardless of whether they were the primary reason for presentation or a secondary diagnosis. Repeat visits for the same episode of infection were not coded. All visits were during routine office hours of 8am to 5pm, Monday to Friday. A minimum level code of M0.00 (Skin/subcutaneous tissue infections) was recorded in the computerised clinical records of appropriate patients using MedTech32 00ae,the electronic patient management system used in all participating practices. Email reminders were sent to GPs every 3-4 weeks during the data collection phase. At the end of this period, the Query Builder 00ae function of MedTech32 00ae was used to design and run a standardised data query. An arbitrary and anonymous unique identifier was assigned to each case and raw data variables including READ code and free-text diagnosis description, date of birth, gender and ethnicity (M ori vs. non-M ori) were extracted and collated centrally. Case definitionCases of skin infection were diagnosed clinically based on the experience of participating GPs, however a written case definition was provided to standardise inclusion criteria: cAny child aged 0-14 years old, seen by a participating GP during the study period, with clinical evidence of a new episode of active bacterial infection of the skin or subcutaneous tissue including any of the following diagnoses: cellulitis, erysipelas, impetigo, subcutaneous abscess, furuncle, carbuncle, acute lymphadenitis, any pyoderma including bacterial super-infection of eczema/scabies/chickenpox/insect bites, and any other infection of the skin or subcutaneous tissue.d Hospital casesWe used anonymised hospitalisation data provided by the New Zealand Ministry of Health to identify all cases of serious skin infection in children aged 0-14 years admitted to Gisborne Hospital over the same 10-week period specified above. The case definition of hospitalised serious skin infection utilised in this study was developed in earlier work by the authors and has been described in detail elsewhere.15Cases were assigned an arbitrary and anonymous unique identifier and the same basic demographic variables as those collated for GP cases were extracted. Data analysisAge and ethnicity-specific skin infection rates from participating GP registers were directly standardised to the regional population to give an estimate of the total number and rate of skin infection cases seen in children in primary care in the Tairawhiti region. Confidence intervals (CIs) were constructed using the methods of Clayton and Hills.16 Denominators in rate calculations were based on usually resident population counts from the 2006 Census. Annual infection rates were calculated from extrapolations of observed data. Seasonal adjustment was not made as recent work has shown there is very little seasonality in hospitalisation rates for skin infections in the Tairawhiti region compared to NZ (see companion articles in this issue of the New Zealand Medical Journal) and it is unknown whether rates of skin infections in primary care exhibit seasonal trends. The ethnicity and gender distribution of children in general practice and in the hospital setting were compared using the Fishers exact test. Age distributions were compared using the Mann Whitney U test. A two-tailed p-value of less than 0.05 was considered statistically significant. Regional Ethics Committee approval was obtained for this study. Results Incidence and characteristics of skin infection cases in primary careOver the 10-week data collection period, 110 incident cases of skin infections in 107 children were recorded by the nine participating GPs. Table 1 summarises the observed number and rate of cases in each age and ethnicity group. Based on age and ethnicity standardisation of observed rates, there were an estimated 378.6 (95%CI: 312.4-458.9) cases of skin infections seen in primary care, equivalent to a rate of 20.5 cases (95%CI: 16.9 to 24.9) per 1000 0-14-year-old children in the Tairawhiti region during the 10-week study period (see Table 1). Extrapolating these data longitudinally, without taking seasonal adjustment into account, there were an estimated 1968.7 (95%CI: 1624.5-2386.3) cases of skin infections in children in the Tairawhiti region primary care setting during 2008. This frequency is equivalent to an annual incidence rate of 106.7 (95%CI: 85.2-127.2) per 1000 children in the region, or 10.7% of the population if there were no repeat infections in the same individuals. In M ori children, there was a trend towards reducing case incidence with increasing age. This trend was less apparent in non-M ori children. Annual infection rates ranged from 29.0 per 1000 for non-M ori children aged 10-14 years, up to 245.5 per 1000 for M ori children aged 0-4 years. Table 1. Skin infection incidence observed in the study population, and estimated for the Tairawhiti region, 0-14 year old children, May-July 2008 Ethnicity/age group Observed case rate per 1000 2020 (no. of cases/no. at risk) Tairawhiti region population 2021 Estimated no. of primary care cases in Tairawhiti region 00a7 Estimated annual rate of primary care cases in Tairawhiti region# M ori 0-4 years 5-9 years 10-14 years 47.2 (34/720) 42.6 (33/774) 24.0 (18/751) 2163 2241 2403 102.1 95.4 57.6 245.5 221.4 124.6 Non-M ori 0-4 years 5-9 years 10-14 years 11.9 (8/671) 14.8 (12/813) 5.6 (5/898) 3651 3852 4146 43.5 56.9 23.1 62.0 76.8 29.0 Total 20.5 (95%CI: 16.9-24.9) 18,456 378.6 (95%CI: 312.4-458.9) 106.7 (95%CI: 85.2-127.2) 95% CI: 95% confidence interval; No.: number. 2020 Ethnicity and age-specific rates of skin infections observed in participating primary care practices during 10-week study period. 2021 Based on usually resident population data in 2006 Census. 00a7 Estimated number of primary care cases of skin infection in children in the Tairawhiti region during the 10-week study period, based on multiplying the age and ethnicity specific rates observed in participating GP practices by the Tairawhiti region population for that age/ethnicity group. # Estimated annual rate per 1000 of primary care cases of skin infection in the Tairawhiti region, based on annualising the 10-week rate (without seasonal adjustment). Comparing skin infection cases seen in primary care and hospital settingsDuring the same 10-week data collection period, 27 cases of serious skin infection in 27 children were admitted to Gisborne Hospital. Based on the estimated 378.6 primary care skin infection cases in the region over this period, there were 14 primary care cases for every one hospitalised serious skin infection. Table 2 and Figure 1 summarise and compare the basic demographic characteristics of primary care and hospital cases seen over the same period in 2008. Most primary care cases were coded only to the minimum code level of M0.00, so information on subtypes of skin infection and free-text diagnosis description was not available. There was a significant difference in the age distribution of skin infection cases between the two settings (p=0.0041). Preschool-aged children accounted for two-thirds (67%) of hospitalised cases of serious skin infection but only 38% of infections in primary care. While just 15% of hospitalised cases were in children aged 5-9 years, this group made up the largest proportion of cases in primary care (41%). The 10-14 year old age group accounted for the smallest proportion of cases overall. Slightly more boys were admitted to hospital with a serious skin infection than girls, 56% and 44% respectively, but this difference did not reach statistical significance. There was no gender predominance in primary care cases with equal numbers of male and female children suffering skin infections. The difference between settings was not significant (p=0.67). Just over three-quarters (77%) of skin infection cases in the primary care setting were in M ori children. Hospitalised cases of serious skin infections exhibited a similar ethnic distribution, with 78% occurring in M ori children (p 1.00). Table 2. Comparison of the demographic characteristics of children with skin infections seen in primary care and hospital settings in the Tairawhiti region, May-July 2008 Variable Primary care cases Hospital cases Difference No. PP (95% CI) No. PH (95% CI) PP - PH p Age (yrs) 0-4 5-9 10-14 42 45 23 0.38(0.30-0.48) 0.41(0.32-0.50) 0.21(0.14-0.29) 18 4 5 0.67(0.48-0.81) 0.15(0.05-0.33) 0.18(0.08-0.37) - 0.29 +0.26 +0.03 0.004 Gender Male Female 55 55 0.50(0.41-0.59) 0.50(0.41-0.59) 15 12 0.56(0.37-0.72) 0.44(0.28-0.63) - 0.06 +0.06 0.67 Ethnicity M ori Non-M ori

Summary

Abstract

Aim

Over the past two decades there has been a documented steady rise in the incidence of hospitalised serious skin infections in New Zealand children. However there are few surveillance data from the primary care setting, where the majority of children with skin infections initially present. We aimed to describe the epidemiology of childhood skin infections presenting to primary care in a region of New Zealand with a particularly high burden of infection and compare this to hospitalised cases during the same period.

Method

A sample of general practitioners in the Tairawhiti (Gisborne) region recorded all cases of skin infections in 0-14 year old children diagnosed over a 10-week period in 2008. Observed case rates were directly standardised by age and ethnicity to the Tairawhiti population to give estimated rates for the whole region. Demographic data from primary care cases were compared to similar data from hospitalised cases during the same period.

Results

There were 110 incident cases of skin infections seen by the nine participating general practitioners during the study period, equivalent to an annual incidence rate of 106.7 (95%CI: 85.2-127.2) cases per 1000 children in the region. For every one hospitalisation there were an estimated 14 primary care cases. Three quarters of skin infections in both primary care and hospital settings occurred in M ori children. There was no gender predominance in either setting, however hospitalised cases of serious skin infections were more likely to occur in the preschool age group whereas children aged 5-9 years predominated at the primary care level.

Conclusion

Skin infections are a common childhood complaint in primary care in the Tairawhiti region, with hospital-based surveillance using coded discharge data only capturing a small proportion of the overall community disease burden. Previously observed ethnic disparities in hospitalisation rates for serious skin infections reflect similar disparities in skin infection rates in primary care. The establishment of a sentinel surveillance system in the New Zealand primary care setting would facilitate further research and monitoring of this and other important conditions.

Author Information

Cathryn OSullivan, Masters of Medical Sciences Student; Michael G Baker, Associate Professor; Department of Public Health, University of Otago, Wellington

Acknowledgements

This work was supported by initial funding from Tairawhiti District Health as part of a larger piece of work made possible by a grant from the New Zealand Ministry of Health Reducing Inequalities Budget. The authors gratefully acknowledge the nine GPs who participated in this study; for their willingness to be involved in this research, and for the time spent coding during already busy consultations. The authors also thank James Stanley who gave generously of his time and statistical expertise; Dr Geoffrey Cramp who provided local project supervision; and the staff of Turanganui PHO and Tairawhiti District Health Clinical Records for the technical assistance they provided.

Correspondence

Associate Professor Michael Baker, Department of Public Health, University of Otago, Wellington. PO Box 7343, Wellington South, New Zealand. Fax: +64 (0)4 3895319

Correspondence Email

michael.baker@otago.ac.nz

Competing Interests

None declared.

Koning S, Mohammedamin RSA, Van Der Wouden JC, et al. Impetigo: Incidence and treatment in Dutch general practice in 1987 and 2001 - Results from two national surveys. Br J Dermatol. 2006;154:239-243.Loffeld A, Davies P, Lewis A, Moss C. Seasonal occurrence of impetigo: a retrospective 8-year review (1996-2003). Clin Exp Dermatol. 2005;30:512-514.Hersh AL, Chambers HF, Maselli JH, Gonzales R. National Trends in Ambulatory Visits and Antibiotic Prescribing for Skin and Soft-Tissue Infections. Arch Intern Med 2008;168:1585-1591.OSullivan C, Baker M, Zhang J. Increasing hospitalisations for serious skin infections in New Zealand children, 1990-2007. Epidemiol Infect. 2010;15:1-11Craig E, Jackson C, Han DY, NZCYES Steering Committee. Monitoring the Health of New Zealand Children and Young People: Indicator Handbook [Internet]. Auckland: Paediatric Society of New Zealand, New Zealand Child and Youth Epidemiology Service; 2007 [cited June 2009]. Available from: http://www.paediatrics.org.nz/files/Indicator%20Handbook%20Version%2008.3.pdfChild Poverty Action Group. Left behind: How social and income inequalities damage New Zealand children [Internet]. Auckland: Child Poverty Action Group; 2008 [cited August 2009]. Available from:http://www.cpag.org.nz/resources/publications/res1213939891.pdfHill PC, Wong CGS, Voss LM, et al. Prospective study of 125 cases of Staphylococcus aureus bacteremia in children in New Zealand. Pediatr Infect Dis J. 2001;20:868-873.Hunt D. Assessing and Reducing the Burden of Serious Skin Infections in Children and Young People in the Greater Wellington Region [Internet]. Wellington: Capital and Coast DHB, Hutt Valley DHB, Regional Public Health; 2004 [cited June 2009]. Available from: http://www.skininfections.co.nz/documents/Serious_Skin_Infections_Nov2004.pdfLawes C. Paediatric cellulitis hospital discharges in the Auckland Region. Auckland: Public Health Protection Service, Auckland Healthcare; 1998.Finger F, Rossaak M, Umstaetter R, et al. Skin infections of the limbs of Polynesian children. NZ Med J. 2004;117:U847.Morgan C, Selak V, Bullen C. Glen Innes Serious Skin Infection Prevention Project: Final Report 1 February 2003 - 31 January 2004 [Internet]. Auckland: Auckland Regional Public Health Services; 2004 [cited June 2009]. Available from:http://www.arphs.govt.nz/Publications_Reports/archive/GlenInnesSkinProject.pdfDepartment of Statistics. New Zealand census of population and dwellings [Internet]. Wellington: Statistics New Zealand; 2006 [cited September 2009]. Available from: http://www.stats.govt.nzSalmond C, Crampton P, Atkinson J. NZDep2006 Index of Deprivation [Internet]. Wellington: Ministry of Health; 2007 [cited August 2009]. Available from:http://www.uow.otago.ac.nz/academic/dph/research/NZDep/NZDep2006%20reserese%20report%2004%20September%202007.pdfChisholm J. The Read clinical classification. Br J Med. 1990;300:1092OSullivan C, Baker M. Proposed epidemiological case definition for serious skin infection in children. J Paediatr Child Health. 2010;46:176-183.Clayton D, Hills M. Statistical Methods in Epidemiology Oxford: Oxford University Press; 1993. p. 80-82.Baker MG, Telfar Barnard L, Kvalsvig A, et al. Increasing incidence of serious infectious diseases and inequalities in a developed country. Lancet, 2012 Feb 17. [Epub ahead of print].Malcolm L. Inequities in access to and utilisation of primary medical care services for M ori and low income New Zealanders. N Z Med J. 1996;109:356-358.Tukuitonga CR, Bell S, Robinson E. Hospital admission among Pacific children Auckland 1992-97. N Z Med J. 2000;113:358-361.Baker M, McNicholas A, Garrett N, et al. Household crowding a major risk factor for epidemic meningococcal disease in Auckland children. Pediatr Infect Dis J. 2000;19:983-990.Grant CC, Scragg R, Tan D, et al. Hospitalization for pneumonia in children in Auckland, New Zealand. J Paediatr Child Health. 1998;34:355-359.Brabyn L, Barnett R. Population need and geographical access to general practitioners in rural New Zealand. NZ Med J. 2004;117:U996.Lawrence D, Facklam R, Sottnek F, et al. Epidemiologic studies among Amerindian populations of Amazonia. I. Pyoderma: prevalence and associated pathogens. Am J Trop Med Hygiene 1979;28:548-58.Elliot AJ, Cross KW, Smith GE, et al. The association between impetigo, insect bites and air temperature: A retrospective 5-year study (1999-2003) using morbidity data collected from a sentinel general practice network database. Fam Pract. 2006;23:490-496.Rogers M, Dorman D, Gapes M, Ly J. A three-year study of impetigo in Sydney. Med J Aust. 1987;147:63-65.Dajani A, Ferrieri P, Wannamaker L. Endemic superficial pyoderma in children. Arch Dermatol 1973;108:517-522.Aho G, Leversha A. General Practice Survey. Background paper prepared for Health Research Council (HRC) Proposal. Auckland; 1999.Baker MG, Easther S, Wilson N. A surveillance sector review applied to infectious diseases at a country level. BMC Public Health 2010;10(332).Brillman JC, Burr T, Forsword D, et al. Modelling emergency department visit patterns for infectious disease complaints: results and application to disease surveillance. BMC Med Inform Decis Mak. 2005;5:4.Broom AK, David WS. The Influenza Surveillance Programme in Western Australia, 2003. Commun Dis Intell 2004;28:169-174.Ansaldi F, Agaro P, Burgnich P. Three year (1999-2002) of epidemiological and virological surveillance of influenza in North-East Italy. Eur J Epidemiol 2004;19:885-890.Deckers JGM, Paget WJ, Scellevis FGl, Fleming D. European primary care surveillance networks: their structure and operation. Fam Pract 2006;23:151-158.Person N, OBrien J, Thomas H, et al. Collecting morbidity data in general practice: the Sommerset morbidity project. 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Skin infections are a common complaint in primary care and are usually considered benign. However, in both New Zealand (NZ) and international settings, these infections are becoming an increasingly significant source of childhood morbidity, with the rate of skin infections requiring hospitalisation (termed serious skin infections) steadily increasing during the last two decades.1-7In NZ, the rate of serious skin infections, doubled between 1990 and 2007.4 In 2004, a report by Hunt found the national rate of cellulitis in children was twice that of Australia and the United States of America.8Recent analyses have found that serious skin infections contribute heavily to health inequalities with the greatest hospitalisation rates observed in M ori and Pacific children.4,5,8-11 These trends are hypothesised to reflect corresponding patterns of disease in the community,8 however there are no published studies examining skin infections in the NZ primary care setting, where many patients initially present and the major burden of illness is managed. This deficit is likely due to the lack of routine primary care level surveillance for most health conditions in NZ.Hospital admissions for serious skin infections represent the tip of the iceberg in relation to the wider community burden of disease.4,8We aimed to estimate the incidence of skin infection cases in primary care in children in the Tairawhiti (Gisborne) region, describe the basic epidemiology of these infections, and compare these characteristics with serious skin infections hospitalised in the region during the same period.Methods We conducted a prospective observational analysis of skin infection cases in children seen by a cohort of general practitioners (GPs) in the Tairawhiti region. Study locationThe Tairawhiti region is a relatively isolated area of 45,000 people on the East Coast of NZs North Island. The region is unique for its large M ori population (47.3% of the total population and 58.4% of the 0-14 year old population), young age distribution (26.2% of people are aged less than 15 years),12 and high levels of deprivation (the Gisborne region has the highest proportion of the most deprived residents in the country).13 In Tairawhiti, childhood skin infections present a major challenge to both primary and secondary health services. The regions serious skin infection incidence is not only the highest in NZ,4 research presented in companion articles in this issue of the New Zealand Medical Journal has shown it is considerably greater than that expected, even after standardising for the high-risk age, ethnicity and deprivation population composition. General practitioner recruitment and data collectionThe raw data for this study were collected by prospective consultation coding by a group of Tairawhiti GPs. All GPs within the region were approached and their voluntary participation in this study sought. Out of the usual local GP population of approximately 20 full-time equivalent practitioners working in six primary practices, nine GPs from three different practices agreed to participate. During the study period, 4627 of the 18,456 (25.1%) 0-14 year olds usually resident population of the Tairawhiti region were registered in the practice populations of these GPs. Over the 10-week period, 19 May 2008 to 28 July 2008, GPs coded all incident cases of skin infection in children using the READ code system. Similar to International Classification of Disease (ICD) codes used in hospitals, READ codes are a standardised and hierarchically-arranged clinical terminology system widely used in primary care practices for coding diagnoses as well as a range of patient demographic and clinical data.14 All skin infections were included regardless of whether they were the primary reason for presentation or a secondary diagnosis. Repeat visits for the same episode of infection were not coded. All visits were during routine office hours of 8am to 5pm, Monday to Friday. A minimum level code of M0.00 (Skin/subcutaneous tissue infections) was recorded in the computerised clinical records of appropriate patients using MedTech32 00ae,the electronic patient management system used in all participating practices. Email reminders were sent to GPs every 3-4 weeks during the data collection phase. At the end of this period, the Query Builder 00ae function of MedTech32 00ae was used to design and run a standardised data query. An arbitrary and anonymous unique identifier was assigned to each case and raw data variables including READ code and free-text diagnosis description, date of birth, gender and ethnicity (M ori vs. non-M ori) were extracted and collated centrally. Case definitionCases of skin infection were diagnosed clinically based on the experience of participating GPs, however a written case definition was provided to standardise inclusion criteria: cAny child aged 0-14 years old, seen by a participating GP during the study period, with clinical evidence of a new episode of active bacterial infection of the skin or subcutaneous tissue including any of the following diagnoses: cellulitis, erysipelas, impetigo, subcutaneous abscess, furuncle, carbuncle, acute lymphadenitis, any pyoderma including bacterial super-infection of eczema/scabies/chickenpox/insect bites, and any other infection of the skin or subcutaneous tissue.d Hospital casesWe used anonymised hospitalisation data provided by the New Zealand Ministry of Health to identify all cases of serious skin infection in children aged 0-14 years admitted to Gisborne Hospital over the same 10-week period specified above. The case definition of hospitalised serious skin infection utilised in this study was developed in earlier work by the authors and has been described in detail elsewhere.15Cases were assigned an arbitrary and anonymous unique identifier and the same basic demographic variables as those collated for GP cases were extracted. Data analysisAge and ethnicity-specific skin infection rates from participating GP registers were directly standardised to the regional population to give an estimate of the total number and rate of skin infection cases seen in children in primary care in the Tairawhiti region. Confidence intervals (CIs) were constructed using the methods of Clayton and Hills.16 Denominators in rate calculations were based on usually resident population counts from the 2006 Census. Annual infection rates were calculated from extrapolations of observed data. Seasonal adjustment was not made as recent work has shown there is very little seasonality in hospitalisation rates for skin infections in the Tairawhiti region compared to NZ (see companion articles in this issue of the New Zealand Medical Journal) and it is unknown whether rates of skin infections in primary care exhibit seasonal trends. The ethnicity and gender distribution of children in general practice and in the hospital setting were compared using the Fishers exact test. Age distributions were compared using the Mann Whitney U test. A two-tailed p-value of less than 0.05 was considered statistically significant. Regional Ethics Committee approval was obtained for this study. Results Incidence and characteristics of skin infection cases in primary careOver the 10-week data collection period, 110 incident cases of skin infections in 107 children were recorded by the nine participating GPs. Table 1 summarises the observed number and rate of cases in each age and ethnicity group. Based on age and ethnicity standardisation of observed rates, there were an estimated 378.6 (95%CI: 312.4-458.9) cases of skin infections seen in primary care, equivalent to a rate of 20.5 cases (95%CI: 16.9 to 24.9) per 1000 0-14-year-old children in the Tairawhiti region during the 10-week study period (see Table 1). Extrapolating these data longitudinally, without taking seasonal adjustment into account, there were an estimated 1968.7 (95%CI: 1624.5-2386.3) cases of skin infections in children in the Tairawhiti region primary care setting during 2008. This frequency is equivalent to an annual incidence rate of 106.7 (95%CI: 85.2-127.2) per 1000 children in the region, or 10.7% of the population if there were no repeat infections in the same individuals. In M ori children, there was a trend towards reducing case incidence with increasing age. This trend was less apparent in non-M ori children. Annual infection rates ranged from 29.0 per 1000 for non-M ori children aged 10-14 years, up to 245.5 per 1000 for M ori children aged 0-4 years. Table 1. Skin infection incidence observed in the study population, and estimated for the Tairawhiti region, 0-14 year old children, May-July 2008 Ethnicity/age group Observed case rate per 1000 2020 (no. of cases/no. at risk) Tairawhiti region population 2021 Estimated no. of primary care cases in Tairawhiti region 00a7 Estimated annual rate of primary care cases in Tairawhiti region# M ori 0-4 years 5-9 years 10-14 years 47.2 (34/720) 42.6 (33/774) 24.0 (18/751) 2163 2241 2403 102.1 95.4 57.6 245.5 221.4 124.6 Non-M ori 0-4 years 5-9 years 10-14 years 11.9 (8/671) 14.8 (12/813) 5.6 (5/898) 3651 3852 4146 43.5 56.9 23.1 62.0 76.8 29.0 Total 20.5 (95%CI: 16.9-24.9) 18,456 378.6 (95%CI: 312.4-458.9) 106.7 (95%CI: 85.2-127.2) 95% CI: 95% confidence interval; No.: number. 2020 Ethnicity and age-specific rates of skin infections observed in participating primary care practices during 10-week study period. 2021 Based on usually resident population data in 2006 Census. 00a7 Estimated number of primary care cases of skin infection in children in the Tairawhiti region during the 10-week study period, based on multiplying the age and ethnicity specific rates observed in participating GP practices by the Tairawhiti region population for that age/ethnicity group. # Estimated annual rate per 1000 of primary care cases of skin infection in the Tairawhiti region, based on annualising the 10-week rate (without seasonal adjustment). Comparing skin infection cases seen in primary care and hospital settingsDuring the same 10-week data collection period, 27 cases of serious skin infection in 27 children were admitted to Gisborne Hospital. Based on the estimated 378.6 primary care skin infection cases in the region over this period, there were 14 primary care cases for every one hospitalised serious skin infection. Table 2 and Figure 1 summarise and compare the basic demographic characteristics of primary care and hospital cases seen over the same period in 2008. Most primary care cases were coded only to the minimum code level of M0.00, so information on subtypes of skin infection and free-text diagnosis description was not available. There was a significant difference in the age distribution of skin infection cases between the two settings (p=0.0041). Preschool-aged children accounted for two-thirds (67%) of hospitalised cases of serious skin infection but only 38% of infections in primary care. While just 15% of hospitalised cases were in children aged 5-9 years, this group made up the largest proportion of cases in primary care (41%). The 10-14 year old age group accounted for the smallest proportion of cases overall. Slightly more boys were admitted to hospital with a serious skin infection than girls, 56% and 44% respectively, but this difference did not reach statistical significance. There was no gender predominance in primary care cases with equal numbers of male and female children suffering skin infections. The difference between settings was not significant (p=0.67). Just over three-quarters (77%) of skin infection cases in the primary care setting were in M ori children. Hospitalised cases of serious skin infections exhibited a similar ethnic distribution, with 78% occurring in M ori children (p 1.00). Table 2. Comparison of the demographic characteristics of children with skin infections seen in primary care and hospital settings in the Tairawhiti region, May-July 2008 Variable Primary care cases Hospital cases Difference No. PP (95% CI) No. PH (95% CI) PP - PH p Age (yrs) 0-4 5-9 10-14 42 45 23 0.38(0.30-0.48) 0.41(0.32-0.50) 0.21(0.14-0.29) 18 4 5 0.67(0.48-0.81) 0.15(0.05-0.33) 0.18(0.08-0.37) - 0.29 +0.26 +0.03 0.004 Gender Male Female 55 55 0.50(0.41-0.59) 0.50(0.41-0.59) 15 12 0.56(0.37-0.72) 0.44(0.28-0.63) - 0.06 +0.06 0.67 Ethnicity M ori Non-M ori

Summary

Abstract

Aim

Over the past two decades there has been a documented steady rise in the incidence of hospitalised serious skin infections in New Zealand children. However there are few surveillance data from the primary care setting, where the majority of children with skin infections initially present. We aimed to describe the epidemiology of childhood skin infections presenting to primary care in a region of New Zealand with a particularly high burden of infection and compare this to hospitalised cases during the same period.

Method

A sample of general practitioners in the Tairawhiti (Gisborne) region recorded all cases of skin infections in 0-14 year old children diagnosed over a 10-week period in 2008. Observed case rates were directly standardised by age and ethnicity to the Tairawhiti population to give estimated rates for the whole region. Demographic data from primary care cases were compared to similar data from hospitalised cases during the same period.

Results

There were 110 incident cases of skin infections seen by the nine participating general practitioners during the study period, equivalent to an annual incidence rate of 106.7 (95%CI: 85.2-127.2) cases per 1000 children in the region. For every one hospitalisation there were an estimated 14 primary care cases. Three quarters of skin infections in both primary care and hospital settings occurred in M ori children. There was no gender predominance in either setting, however hospitalised cases of serious skin infections were more likely to occur in the preschool age group whereas children aged 5-9 years predominated at the primary care level.

Conclusion

Skin infections are a common childhood complaint in primary care in the Tairawhiti region, with hospital-based surveillance using coded discharge data only capturing a small proportion of the overall community disease burden. Previously observed ethnic disparities in hospitalisation rates for serious skin infections reflect similar disparities in skin infection rates in primary care. The establishment of a sentinel surveillance system in the New Zealand primary care setting would facilitate further research and monitoring of this and other important conditions.

Author Information

Cathryn OSullivan, Masters of Medical Sciences Student; Michael G Baker, Associate Professor; Department of Public Health, University of Otago, Wellington

Acknowledgements

This work was supported by initial funding from Tairawhiti District Health as part of a larger piece of work made possible by a grant from the New Zealand Ministry of Health Reducing Inequalities Budget. The authors gratefully acknowledge the nine GPs who participated in this study; for their willingness to be involved in this research, and for the time spent coding during already busy consultations. The authors also thank James Stanley who gave generously of his time and statistical expertise; Dr Geoffrey Cramp who provided local project supervision; and the staff of Turanganui PHO and Tairawhiti District Health Clinical Records for the technical assistance they provided.

Correspondence

Associate Professor Michael Baker, Department of Public Health, University of Otago, Wellington. PO Box 7343, Wellington South, New Zealand. Fax: +64 (0)4 3895319

Correspondence Email

michael.baker@otago.ac.nz

Competing Interests

None declared.

Koning S, Mohammedamin RSA, Van Der Wouden JC, et al. Impetigo: Incidence and treatment in Dutch general practice in 1987 and 2001 - Results from two national surveys. Br J Dermatol. 2006;154:239-243.Loffeld A, Davies P, Lewis A, Moss C. Seasonal occurrence of impetigo: a retrospective 8-year review (1996-2003). Clin Exp Dermatol. 2005;30:512-514.Hersh AL, Chambers HF, Maselli JH, Gonzales R. National Trends in Ambulatory Visits and Antibiotic Prescribing for Skin and Soft-Tissue Infections. Arch Intern Med 2008;168:1585-1591.OSullivan C, Baker M, Zhang J. Increasing hospitalisations for serious skin infections in New Zealand children, 1990-2007. Epidemiol Infect. 2010;15:1-11Craig E, Jackson C, Han DY, NZCYES Steering Committee. Monitoring the Health of New Zealand Children and Young People: Indicator Handbook [Internet]. Auckland: Paediatric Society of New Zealand, New Zealand Child and Youth Epidemiology Service; 2007 [cited June 2009]. Available from: http://www.paediatrics.org.nz/files/Indicator%20Handbook%20Version%2008.3.pdfChild Poverty Action Group. Left behind: How social and income inequalities damage New Zealand children [Internet]. Auckland: Child Poverty Action Group; 2008 [cited August 2009]. Available from:http://www.cpag.org.nz/resources/publications/res1213939891.pdfHill PC, Wong CGS, Voss LM, et al. Prospective study of 125 cases of Staphylococcus aureus bacteremia in children in New Zealand. Pediatr Infect Dis J. 2001;20:868-873.Hunt D. Assessing and Reducing the Burden of Serious Skin Infections in Children and Young People in the Greater Wellington Region [Internet]. Wellington: Capital and Coast DHB, Hutt Valley DHB, Regional Public Health; 2004 [cited June 2009]. Available from: http://www.skininfections.co.nz/documents/Serious_Skin_Infections_Nov2004.pdfLawes C. Paediatric cellulitis hospital discharges in the Auckland Region. Auckland: Public Health Protection Service, Auckland Healthcare; 1998.Finger F, Rossaak M, Umstaetter R, et al. Skin infections of the limbs of Polynesian children. NZ Med J. 2004;117:U847.Morgan C, Selak V, Bullen C. Glen Innes Serious Skin Infection Prevention Project: Final Report 1 February 2003 - 31 January 2004 [Internet]. Auckland: Auckland Regional Public Health Services; 2004 [cited June 2009]. Available from:http://www.arphs.govt.nz/Publications_Reports/archive/GlenInnesSkinProject.pdfDepartment of Statistics. New Zealand census of population and dwellings [Internet]. Wellington: Statistics New Zealand; 2006 [cited September 2009]. Available from: http://www.stats.govt.nzSalmond C, Crampton P, Atkinson J. NZDep2006 Index of Deprivation [Internet]. Wellington: Ministry of Health; 2007 [cited August 2009]. Available from:http://www.uow.otago.ac.nz/academic/dph/research/NZDep/NZDep2006%20reserese%20report%2004%20September%202007.pdfChisholm J. The Read clinical classification. Br J Med. 1990;300:1092OSullivan C, Baker M. Proposed epidemiological case definition for serious skin infection in children. J Paediatr Child Health. 2010;46:176-183.Clayton D, Hills M. Statistical Methods in Epidemiology Oxford: Oxford University Press; 1993. p. 80-82.Baker MG, Telfar Barnard L, Kvalsvig A, et al. Increasing incidence of serious infectious diseases and inequalities in a developed country. Lancet, 2012 Feb 17. [Epub ahead of print].Malcolm L. Inequities in access to and utilisation of primary medical care services for M ori and low income New Zealanders. N Z Med J. 1996;109:356-358.Tukuitonga CR, Bell S, Robinson E. Hospital admission among Pacific children Auckland 1992-97. N Z Med J. 2000;113:358-361.Baker M, McNicholas A, Garrett N, et al. Household crowding a major risk factor for epidemic meningococcal disease in Auckland children. Pediatr Infect Dis J. 2000;19:983-990.Grant CC, Scragg R, Tan D, et al. Hospitalization for pneumonia in children in Auckland, New Zealand. J Paediatr Child Health. 1998;34:355-359.Brabyn L, Barnett R. Population need and geographical access to general practitioners in rural New Zealand. NZ Med J. 2004;117:U996.Lawrence D, Facklam R, Sottnek F, et al. Epidemiologic studies among Amerindian populations of Amazonia. I. Pyoderma: prevalence and associated pathogens. Am J Trop Med Hygiene 1979;28:548-58.Elliot AJ, Cross KW, Smith GE, et al. The association between impetigo, insect bites and air temperature: A retrospective 5-year study (1999-2003) using morbidity data collected from a sentinel general practice network database. Fam Pract. 2006;23:490-496.Rogers M, Dorman D, Gapes M, Ly J. A three-year study of impetigo in Sydney. Med J Aust. 1987;147:63-65.Dajani A, Ferrieri P, Wannamaker L. Endemic superficial pyoderma in children. Arch Dermatol 1973;108:517-522.Aho G, Leversha A. General Practice Survey. Background paper prepared for Health Research Council (HRC) Proposal. Auckland; 1999.Baker MG, Easther S, Wilson N. A surveillance sector review applied to infectious diseases at a country level. BMC Public Health 2010;10(332).Brillman JC, Burr T, Forsword D, et al. Modelling emergency department visit patterns for infectious disease complaints: results and application to disease surveillance. BMC Med Inform Decis Mak. 2005;5:4.Broom AK, David WS. The Influenza Surveillance Programme in Western Australia, 2003. Commun Dis Intell 2004;28:169-174.Ansaldi F, Agaro P, Burgnich P. Three year (1999-2002) of epidemiological and virological surveillance of influenza in North-East Italy. Eur J Epidemiol 2004;19:885-890.Deckers JGM, Paget WJ, Scellevis FGl, Fleming D. European primary care surveillance networks: their structure and operation. Fam Pract 2006;23:151-158.Person N, OBrien J, Thomas H, et al. Collecting morbidity data in general practice: the Sommerset morbidity project. BMJ. 1996;312:1517-1520.Jones NF, Marshall R. Evaluation of an electronic general-practitioner-basedsyndromic surveillance system - Auckland, New Zealand, 2000-2001. MMWR. 2004;53(Suppl):173-178.

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Skin infections are a common complaint in primary care and are usually considered benign. However, in both New Zealand (NZ) and international settings, these infections are becoming an increasingly significant source of childhood morbidity, with the rate of skin infections requiring hospitalisation (termed serious skin infections) steadily increasing during the last two decades.1-7In NZ, the rate of serious skin infections, doubled between 1990 and 2007.4 In 2004, a report by Hunt found the national rate of cellulitis in children was twice that of Australia and the United States of America.8Recent analyses have found that serious skin infections contribute heavily to health inequalities with the greatest hospitalisation rates observed in M ori and Pacific children.4,5,8-11 These trends are hypothesised to reflect corresponding patterns of disease in the community,8 however there are no published studies examining skin infections in the NZ primary care setting, where many patients initially present and the major burden of illness is managed. This deficit is likely due to the lack of routine primary care level surveillance for most health conditions in NZ.Hospital admissions for serious skin infections represent the tip of the iceberg in relation to the wider community burden of disease.4,8We aimed to estimate the incidence of skin infection cases in primary care in children in the Tairawhiti (Gisborne) region, describe the basic epidemiology of these infections, and compare these characteristics with serious skin infections hospitalised in the region during the same period.Methods We conducted a prospective observational analysis of skin infection cases in children seen by a cohort of general practitioners (GPs) in the Tairawhiti region. Study locationThe Tairawhiti region is a relatively isolated area of 45,000 people on the East Coast of NZs North Island. The region is unique for its large M ori population (47.3% of the total population and 58.4% of the 0-14 year old population), young age distribution (26.2% of people are aged less than 15 years),12 and high levels of deprivation (the Gisborne region has the highest proportion of the most deprived residents in the country).13 In Tairawhiti, childhood skin infections present a major challenge to both primary and secondary health services. The regions serious skin infection incidence is not only the highest in NZ,4 research presented in companion articles in this issue of the New Zealand Medical Journal has shown it is considerably greater than that expected, even after standardising for the high-risk age, ethnicity and deprivation population composition. General practitioner recruitment and data collectionThe raw data for this study were collected by prospective consultation coding by a group of Tairawhiti GPs. All GPs within the region were approached and their voluntary participation in this study sought. Out of the usual local GP population of approximately 20 full-time equivalent practitioners working in six primary practices, nine GPs from three different practices agreed to participate. During the study period, 4627 of the 18,456 (25.1%) 0-14 year olds usually resident population of the Tairawhiti region were registered in the practice populations of these GPs. Over the 10-week period, 19 May 2008 to 28 July 2008, GPs coded all incident cases of skin infection in children using the READ code system. Similar to International Classification of Disease (ICD) codes used in hospitals, READ codes are a standardised and hierarchically-arranged clinical terminology system widely used in primary care practices for coding diagnoses as well as a range of patient demographic and clinical data.14 All skin infections were included regardless of whether they were the primary reason for presentation or a secondary diagnosis. Repeat visits for the same episode of infection were not coded. All visits were during routine office hours of 8am to 5pm, Monday to Friday. A minimum level code of M0.00 (Skin/subcutaneous tissue infections) was recorded in the computerised clinical records of appropriate patients using MedTech32 00ae,the electronic patient management system used in all participating practices. Email reminders were sent to GPs every 3-4 weeks during the data collection phase. At the end of this period, the Query Builder 00ae function of MedTech32 00ae was used to design and run a standardised data query. An arbitrary and anonymous unique identifier was assigned to each case and raw data variables including READ code and free-text diagnosis description, date of birth, gender and ethnicity (M ori vs. non-M ori) were extracted and collated centrally. Case definitionCases of skin infection were diagnosed clinically based on the experience of participating GPs, however a written case definition was provided to standardise inclusion criteria: cAny child aged 0-14 years old, seen by a participating GP during the study period, with clinical evidence of a new episode of active bacterial infection of the skin or subcutaneous tissue including any of the following diagnoses: cellulitis, erysipelas, impetigo, subcutaneous abscess, furuncle, carbuncle, acute lymphadenitis, any pyoderma including bacterial super-infection of eczema/scabies/chickenpox/insect bites, and any other infection of the skin or subcutaneous tissue.d Hospital casesWe used anonymised hospitalisation data provided by the New Zealand Ministry of Health to identify all cases of serious skin infection in children aged 0-14 years admitted to Gisborne Hospital over the same 10-week period specified above. The case definition of hospitalised serious skin infection utilised in this study was developed in earlier work by the authors and has been described in detail elsewhere.15Cases were assigned an arbitrary and anonymous unique identifier and the same basic demographic variables as those collated for GP cases were extracted. Data analysisAge and ethnicity-specific skin infection rates from participating GP registers were directly standardised to the regional population to give an estimate of the total number and rate of skin infection cases seen in children in primary care in the Tairawhiti region. Confidence intervals (CIs) were constructed using the methods of Clayton and Hills.16 Denominators in rate calculations were based on usually resident population counts from the 2006 Census. Annual infection rates were calculated from extrapolations of observed data. Seasonal adjustment was not made as recent work has shown there is very little seasonality in hospitalisation rates for skin infections in the Tairawhiti region compared to NZ (see companion articles in this issue of the New Zealand Medical Journal) and it is unknown whether rates of skin infections in primary care exhibit seasonal trends. The ethnicity and gender distribution of children in general practice and in the hospital setting were compared using the Fishers exact test. Age distributions were compared using the Mann Whitney U test. A two-tailed p-value of less than 0.05 was considered statistically significant. Regional Ethics Committee approval was obtained for this study. Results Incidence and characteristics of skin infection cases in primary careOver the 10-week data collection period, 110 incident cases of skin infections in 107 children were recorded by the nine participating GPs. Table 1 summarises the observed number and rate of cases in each age and ethnicity group. Based on age and ethnicity standardisation of observed rates, there were an estimated 378.6 (95%CI: 312.4-458.9) cases of skin infections seen in primary care, equivalent to a rate of 20.5 cases (95%CI: 16.9 to 24.9) per 1000 0-14-year-old children in the Tairawhiti region during the 10-week study period (see Table 1). Extrapolating these data longitudinally, without taking seasonal adjustment into account, there were an estimated 1968.7 (95%CI: 1624.5-2386.3) cases of skin infections in children in the Tairawhiti region primary care setting during 2008. This frequency is equivalent to an annual incidence rate of 106.7 (95%CI: 85.2-127.2) per 1000 children in the region, or 10.7% of the population if there were no repeat infections in the same individuals. In M ori children, there was a trend towards reducing case incidence with increasing age. This trend was less apparent in non-M ori children. Annual infection rates ranged from 29.0 per 1000 for non-M ori children aged 10-14 years, up to 245.5 per 1000 for M ori children aged 0-4 years. Table 1. Skin infection incidence observed in the study population, and estimated for the Tairawhiti region, 0-14 year old children, May-July 2008 Ethnicity/age group Observed case rate per 1000 2020 (no. of cases/no. at risk) Tairawhiti region population 2021 Estimated no. of primary care cases in Tairawhiti region 00a7 Estimated annual rate of primary care cases in Tairawhiti region# M ori 0-4 years 5-9 years 10-14 years 47.2 (34/720) 42.6 (33/774) 24.0 (18/751) 2163 2241 2403 102.1 95.4 57.6 245.5 221.4 124.6 Non-M ori 0-4 years 5-9 years 10-14 years 11.9 (8/671) 14.8 (12/813) 5.6 (5/898) 3651 3852 4146 43.5 56.9 23.1 62.0 76.8 29.0 Total 20.5 (95%CI: 16.9-24.9) 18,456 378.6 (95%CI: 312.4-458.9) 106.7 (95%CI: 85.2-127.2) 95% CI: 95% confidence interval; No.: number. 2020 Ethnicity and age-specific rates of skin infections observed in participating primary care practices during 10-week study period. 2021 Based on usually resident population data in 2006 Census. 00a7 Estimated number of primary care cases of skin infection in children in the Tairawhiti region during the 10-week study period, based on multiplying the age and ethnicity specific rates observed in participating GP practices by the Tairawhiti region population for that age/ethnicity group. # Estimated annual rate per 1000 of primary care cases of skin infection in the Tairawhiti region, based on annualising the 10-week rate (without seasonal adjustment). Comparing skin infection cases seen in primary care and hospital settingsDuring the same 10-week data collection period, 27 cases of serious skin infection in 27 children were admitted to Gisborne Hospital. Based on the estimated 378.6 primary care skin infection cases in the region over this period, there were 14 primary care cases for every one hospitalised serious skin infection. Table 2 and Figure 1 summarise and compare the basic demographic characteristics of primary care and hospital cases seen over the same period in 2008. Most primary care cases were coded only to the minimum code level of M0.00, so information on subtypes of skin infection and free-text diagnosis description was not available. There was a significant difference in the age distribution of skin infection cases between the two settings (p=0.0041). Preschool-aged children accounted for two-thirds (67%) of hospitalised cases of serious skin infection but only 38% of infections in primary care. While just 15% of hospitalised cases were in children aged 5-9 years, this group made up the largest proportion of cases in primary care (41%). The 10-14 year old age group accounted for the smallest proportion of cases overall. Slightly more boys were admitted to hospital with a serious skin infection than girls, 56% and 44% respectively, but this difference did not reach statistical significance. There was no gender predominance in primary care cases with equal numbers of male and female children suffering skin infections. The difference between settings was not significant (p=0.67). Just over three-quarters (77%) of skin infection cases in the primary care setting were in M ori children. Hospitalised cases of serious skin infections exhibited a similar ethnic distribution, with 78% occurring in M ori children (p 1.00). Table 2. Comparison of the demographic characteristics of children with skin infections seen in primary care and hospital settings in the Tairawhiti region, May-July 2008 Variable Primary care cases Hospital cases Difference No. PP (95% CI) No. PH (95% CI) PP - PH p Age (yrs) 0-4 5-9 10-14 42 45 23 0.38(0.30-0.48) 0.41(0.32-0.50) 0.21(0.14-0.29) 18 4 5 0.67(0.48-0.81) 0.15(0.05-0.33) 0.18(0.08-0.37) - 0.29 +0.26 +0.03 0.004 Gender Male Female 55 55 0.50(0.41-0.59) 0.50(0.41-0.59) 15 12 0.56(0.37-0.72) 0.44(0.28-0.63) - 0.06 +0.06 0.67 Ethnicity M ori Non-M ori

Summary

Abstract

Aim

Over the past two decades there has been a documented steady rise in the incidence of hospitalised serious skin infections in New Zealand children. However there are few surveillance data from the primary care setting, where the majority of children with skin infections initially present. We aimed to describe the epidemiology of childhood skin infections presenting to primary care in a region of New Zealand with a particularly high burden of infection and compare this to hospitalised cases during the same period.

Method

A sample of general practitioners in the Tairawhiti (Gisborne) region recorded all cases of skin infections in 0-14 year old children diagnosed over a 10-week period in 2008. Observed case rates were directly standardised by age and ethnicity to the Tairawhiti population to give estimated rates for the whole region. Demographic data from primary care cases were compared to similar data from hospitalised cases during the same period.

Results

There were 110 incident cases of skin infections seen by the nine participating general practitioners during the study period, equivalent to an annual incidence rate of 106.7 (95%CI: 85.2-127.2) cases per 1000 children in the region. For every one hospitalisation there were an estimated 14 primary care cases. Three quarters of skin infections in both primary care and hospital settings occurred in M ori children. There was no gender predominance in either setting, however hospitalised cases of serious skin infections were more likely to occur in the preschool age group whereas children aged 5-9 years predominated at the primary care level.

Conclusion

Skin infections are a common childhood complaint in primary care in the Tairawhiti region, with hospital-based surveillance using coded discharge data only capturing a small proportion of the overall community disease burden. Previously observed ethnic disparities in hospitalisation rates for serious skin infections reflect similar disparities in skin infection rates in primary care. The establishment of a sentinel surveillance system in the New Zealand primary care setting would facilitate further research and monitoring of this and other important conditions.

Author Information

Cathryn OSullivan, Masters of Medical Sciences Student; Michael G Baker, Associate Professor; Department of Public Health, University of Otago, Wellington

Acknowledgements

This work was supported by initial funding from Tairawhiti District Health as part of a larger piece of work made possible by a grant from the New Zealand Ministry of Health Reducing Inequalities Budget. The authors gratefully acknowledge the nine GPs who participated in this study; for their willingness to be involved in this research, and for the time spent coding during already busy consultations. The authors also thank James Stanley who gave generously of his time and statistical expertise; Dr Geoffrey Cramp who provided local project supervision; and the staff of Turanganui PHO and Tairawhiti District Health Clinical Records for the technical assistance they provided.

Correspondence

Associate Professor Michael Baker, Department of Public Health, University of Otago, Wellington. PO Box 7343, Wellington South, New Zealand. Fax: +64 (0)4 3895319

Correspondence Email

michael.baker@otago.ac.nz

Competing Interests

None declared.

Koning S, Mohammedamin RSA, Van Der Wouden JC, et al. Impetigo: Incidence and treatment in Dutch general practice in 1987 and 2001 - Results from two national surveys. Br J Dermatol. 2006;154:239-243.Loffeld A, Davies P, Lewis A, Moss C. Seasonal occurrence of impetigo: a retrospective 8-year review (1996-2003). Clin Exp Dermatol. 2005;30:512-514.Hersh AL, Chambers HF, Maselli JH, Gonzales R. National Trends in Ambulatory Visits and Antibiotic Prescribing for Skin and Soft-Tissue Infections. Arch Intern Med 2008;168:1585-1591.OSullivan C, Baker M, Zhang J. Increasing hospitalisations for serious skin infections in New Zealand children, 1990-2007. Epidemiol Infect. 2010;15:1-11Craig E, Jackson C, Han DY, NZCYES Steering Committee. Monitoring the Health of New Zealand Children and Young People: Indicator Handbook [Internet]. Auckland: Paediatric Society of New Zealand, New Zealand Child and Youth Epidemiology Service; 2007 [cited June 2009]. Available from: http://www.paediatrics.org.nz/files/Indicator%20Handbook%20Version%2008.3.pdfChild Poverty Action Group. Left behind: How social and income inequalities damage New Zealand children [Internet]. Auckland: Child Poverty Action Group; 2008 [cited August 2009]. Available from:http://www.cpag.org.nz/resources/publications/res1213939891.pdfHill PC, Wong CGS, Voss LM, et al. Prospective study of 125 cases of Staphylococcus aureus bacteremia in children in New Zealand. Pediatr Infect Dis J. 2001;20:868-873.Hunt D. Assessing and Reducing the Burden of Serious Skin Infections in Children and Young People in the Greater Wellington Region [Internet]. Wellington: Capital and Coast DHB, Hutt Valley DHB, Regional Public Health; 2004 [cited June 2009]. Available from: http://www.skininfections.co.nz/documents/Serious_Skin_Infections_Nov2004.pdfLawes C. Paediatric cellulitis hospital discharges in the Auckland Region. Auckland: Public Health Protection Service, Auckland Healthcare; 1998.Finger F, Rossaak M, Umstaetter R, et al. Skin infections of the limbs of Polynesian children. NZ Med J. 2004;117:U847.Morgan C, Selak V, Bullen C. Glen Innes Serious Skin Infection Prevention Project: Final Report 1 February 2003 - 31 January 2004 [Internet]. Auckland: Auckland Regional Public Health Services; 2004 [cited June 2009]. Available from:http://www.arphs.govt.nz/Publications_Reports/archive/GlenInnesSkinProject.pdfDepartment of Statistics. New Zealand census of population and dwellings [Internet]. Wellington: Statistics New Zealand; 2006 [cited September 2009]. Available from: http://www.stats.govt.nzSalmond C, Crampton P, Atkinson J. NZDep2006 Index of Deprivation [Internet]. Wellington: Ministry of Health; 2007 [cited August 2009]. Available from:http://www.uow.otago.ac.nz/academic/dph/research/NZDep/NZDep2006%20reserese%20report%2004%20September%202007.pdfChisholm J. The Read clinical classification. Br J Med. 1990;300:1092OSullivan C, Baker M. Proposed epidemiological case definition for serious skin infection in children. J Paediatr Child Health. 2010;46:176-183.Clayton D, Hills M. Statistical Methods in Epidemiology Oxford: Oxford University Press; 1993. p. 80-82.Baker MG, Telfar Barnard L, Kvalsvig A, et al. Increasing incidence of serious infectious diseases and inequalities in a developed country. Lancet, 2012 Feb 17. [Epub ahead of print].Malcolm L. Inequities in access to and utilisation of primary medical care services for M ori and low income New Zealanders. N Z Med J. 1996;109:356-358.Tukuitonga CR, Bell S, Robinson E. Hospital admission among Pacific children Auckland 1992-97. N Z Med J. 2000;113:358-361.Baker M, McNicholas A, Garrett N, et al. Household crowding a major risk factor for epidemic meningococcal disease in Auckland children. Pediatr Infect Dis J. 2000;19:983-990.Grant CC, Scragg R, Tan D, et al. Hospitalization for pneumonia in children in Auckland, New Zealand. J Paediatr Child Health. 1998;34:355-359.Brabyn L, Barnett R. Population need and geographical access to general practitioners in rural New Zealand. NZ Med J. 2004;117:U996.Lawrence D, Facklam R, Sottnek F, et al. Epidemiologic studies among Amerindian populations of Amazonia. I. Pyoderma: prevalence and associated pathogens. Am J Trop Med Hygiene 1979;28:548-58.Elliot AJ, Cross KW, Smith GE, et al. The association between impetigo, insect bites and air temperature: A retrospective 5-year study (1999-2003) using morbidity data collected from a sentinel general practice network database. Fam Pract. 2006;23:490-496.Rogers M, Dorman D, Gapes M, Ly J. A three-year study of impetigo in Sydney. Med J Aust. 1987;147:63-65.Dajani A, Ferrieri P, Wannamaker L. Endemic superficial pyoderma in children. Arch Dermatol 1973;108:517-522.Aho G, Leversha A. General Practice Survey. Background paper prepared for Health Research Council (HRC) Proposal. Auckland; 1999.Baker MG, Easther S, Wilson N. A surveillance sector review applied to infectious diseases at a country level. BMC Public Health 2010;10(332).Brillman JC, Burr T, Forsword D, et al. Modelling emergency department visit patterns for infectious disease complaints: results and application to disease surveillance. BMC Med Inform Decis Mak. 2005;5:4.Broom AK, David WS. The Influenza Surveillance Programme in Western Australia, 2003. Commun Dis Intell 2004;28:169-174.Ansaldi F, Agaro P, Burgnich P. Three year (1999-2002) of epidemiological and virological surveillance of influenza in North-East Italy. Eur J Epidemiol 2004;19:885-890.Deckers JGM, Paget WJ, Scellevis FGl, Fleming D. European primary care surveillance networks: their structure and operation. Fam Pract 2006;23:151-158.Person N, OBrien J, Thomas H, et al. Collecting morbidity data in general practice: the Sommerset morbidity project. BMJ. 1996;312:1517-1520.Jones NF, Marshall R. Evaluation of an electronic general-practitioner-basedsyndromic surveillance system - Auckland, New Zealand, 2000-2001. MMWR. 2004;53(Suppl):173-178.

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