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Type 1 diabetes is the most common endocrine disorder in children and adolescents.1 Type 1 diabetes in youth may have profound long-term complications, if poorly managed. Long-term complications may contribute to life-lasting disabilities and chronic diseases, such as blindness, kidney failure, nerve damage, circulatory problems, heart disease, and early death.2,3The onset of long-term complications can be prevented or delayed if good diabetes management is achieved,4 thereby reducing the costs for the individual and their family, and to the healthcare system.The incidence and prevalence of type 1 diabetes is increasing nationally and internationally.5-7For example, over a 30-year period in the Canterbury geographical region, the incidence of type 1 diabetes in children and adolescents (0-19 years) was found to have significantly increased with time.6The incidence rate of type 1 diabetes over time was significant in children (0-14 year olds).6Whereas there were insignificant changes in the rate of new presentations of type 1 diabetes with time in adolescents (15-19 year olds).6 The last study of the prevalence of type 1 diabetes in youth (0-24 year olds) in the Canterbury District Health Board (CDHB) indicated a prevalence of 227 per 100,000 population.8 The present study provides up-to-date data on the number and prevalence of youth with type 1 diabetes. The aims of this paper were to Describe the demographics of youth (15-24 year olds) with type 1 diabetes in the CDHB catchment area and to compare this data with previous research.8 Calculate the prevalence of youth with type 1 diabetes in the CDHB catchment area. Investigate whether there has been an increase in the prevalence of youth with type 1 diabetes residing within the CDHB catchment area. Methods The study comprised two main phases - data collection and data analysis. The project involved collating information for youth with type 1 diabetes aged between 15 and 24 years, residing within the CDHB catchment area. This included Christchurch, the town of Ashburton, and Northern rural Canterbury. South Canterbury District Health Board (SCDHB) entries were excluded from the study. The number of youth residing in the identified catchment area based on an anchor date of 1 November 2010 was calculated. This date was aligned with the previous study's anchor date,8yielding a 7-year gap between the two studies. The search criteria (i.e. valid entries) used in the previous study was followed.8 Thus, those with newly diagnosed and patients with secondary or type 2 diabetes were excluded from the study. CDHB records were searched in multiple electronic and physical sources. The electronic data sources included the CDHB inpatient and outpatients lists; the Diabetes Youth Canterbury database; and records from the previous study.8 The data collected comprised descriptive information and demographic characteristics of the youth. This included gender, ethnicity, age, residential area deprivation level,9 and diabetes duration. Missing data-point entries were updated by searching the physical files held at the CDHB Diabetes Centre based on the National Health Index (NHI), and contacting the individual youth's General Practitioner (GP). The collated data was entered in raw format using Microsoft Excel 2007 and IBM Statistical Package for Social Sciences (IBM SPSS 19). These software packages were used in the first (data collection) and second (data analysis) phases of the study. Age data was divided into two age bands (15-19 years and 20-24 years), representing adolescents and young adult developmental stages. In the second phase, the prevalence of youth with type 1 diabetes was calculated, and then this was compared to the results of the last audit's study that was conducted in the CDHB in 2003.8 In the present research, the prevalence calculation was based on the 2006 census data, whereas the 2003 prevalence calculation was based on the 2001 census data.10 Prior to comparing the two results, the studies populations were checked for adequate comparability. The checking for this revealed two potential points of difference. The first potential point of difference point was related to maintaining the unity of the source of the obtained census lists. It was established that both of the census population figures were drawn from the same source of either Total Responses or Prioritised lists.11 The second point was related to the different data collection and entry system of the 2001 and the 2006 census. For example, the ‘New Zealander' entry was grouped with the European entry in the 2001 census data; however, in 2006 a separate classification under ‘other ethnicities' was created to sum the New Zealander entries.11 To overcome this issue, the total number of the New Zealander subcategory in the 2006 census data was added to total number of the European category, thus making the 2001 and 2006 census population totals comparable to each other. After ensuring the populations comparability, the 2010 and 2003 prevalences were compared. This process involved calculating the difference between the prevalences, and the 95% confidence interval (CI) of this difference.12-14 This difference was then statistically tested for significance.12-14 Results The number of youth with type 1 diabetes residing within the CDHB catchment area on the anchor date 1 November 2010 was 248. The demographics of these youth are depicted in Table 1. Table 1. Demographics of youth with type 1 diabetes, who are residing within the CDHB catchment area in 2010 Variables Count N% Gender Female 120 48.4% Male 128 51.6% Age groups* (years) (15-19) 131 52.8% (20-24) 117 47.2% Ethnicity European 227 91.5% Maori 9 3.6% Pacific Peoples 3 1.2% Other 9 3.6% Diabetes duration** (years) between 1 and 5 55 22.2% between 6 and 10 82 33.1% between 11 and 15 68 27.4% between 16 and 20 33 13.3% more than 20 10 4.0% Deprivation quintiles (1 = least deprived areas) 1 77 31.2% 2 55 22.3% 3 55 22.3% 4 35 14.2% 5 25 10.1% * Mean age was 19.2 years old (standard deviation (std. dev.) =2.6 years) ** Mean length of diagnosis was 10 years (std. dev. =5.4 years; minimum =0.9 year (11 months); maximum=22 years). The prevalence calculation only included entries of established diabetes. This included diabetes duration that is around 1 year or more. Based on the total number of youth with type 1 diabetes residing within the CDHB catchment area in 2010, the prevalence was calculated using the 2006 census data.10 The calculation was stratified according to ethnicity. Additionally, the European ethnic group had sufficient numbers to allow for the stratifying of data into two age bands (15-19 years and 20-24 years), which correspond to the census age categories. The results are shown in Table 2. Table 2. Number and prevalence of European New Zealanders with type 1 diabetes (stratified by age) residing in the Canterbury District Health Board Catchment Area in 2010 and 2003 Anchor date (15-19 years old) (20-24 years old) Total 1 November 2010 Number 126 101 227 Prevalence per 100,000 (95%CI X to Y) 443 (372 to 527) 406 (334 to 493) 426 (374 to 484) Total population10 28,452 24,891 53,343 Anchor date 1 November 2003 (15-19 years old) (20-24 years old) Total Number8 92 95 187 Prevalence per 100,000 (95%CI X-Y) 369 (301 to 452) 394 (322 to 481) 381 (330 to 440) Total population15 24,951 24,126 49,077 The total prevalence from the present study was compared with the prevalence obtained by the previous study (Table 2),8 after ensuring the comparability of data as previously described. The comparison yielded an increase of 45 per 100,000 (12%)population. However, the 95% confidence interval for this prevalence difference ranged from -33 to +122 indicating that this increase was not statistically significant. From 2003 to 2010 there was a prevalence increase of 74 per 100,000 (20%) in adolescents (15 to 19 year olds), and 12 per 100,000 (3%) in young adults (20 to 24 year olds) with type 1 diabetes. However, the prevalence increase was statistically insignificant in each age band, from 2003 to 2010, according to the confidence interval of the difference: (95%CI -35 to 182) and (95%CI -101 to 125) per 100,000 adolescents and young adults, respectively. Comparing the total populations in Table 2 suggests that the adolescents' age band had an increase of 14% compared to a 3% increase in the young adults' total population.

Summary

Abstract

Aim

The aim of the present study was to provide up-to-date descriptive information in relation to youth (15-24 years) with type 1 diabetes, residing within the Canterbury District Health Board (CDHB) catchment area. This included calculating the prevalence of type 1 diabetes in youth, and investigating whether there was an increase in the prevalence since a previous study reporting the prevalence of type 1 diabetes in youth in the CDHB in 2003.

Method

Data were collected from multiple clinical and research sources. Descriptive information and emographic characteristics, including age, gender, ethnicity, deprivation level, and diabetes duration were gathered. The prevalence, stratified by age and ethnicity, was calculated using the 2006 population census data.

Results

There were 248 people with type 1 diabetes aged between 15 and 24 years residing within the CDHB area at the time of present study, giving a prevalence of 426 per 100,000 European youth with type 1 diabetes. The prevalence is found to have increased by 45 per 100,000 (12%) since 2003, but was statistically insignificant.

Conclusion

There was no statistically significant increase in the prevalence of type 1 diabetes in youth in the CDHB catchment area between 2003 and 2010. However, the absolute figures of adolescents and young adults with type 1 diabetes have increased, which implies an increased demand on health care associated with diabetes compared to 7 years ago.

Author Information

Balsam Obaid, PhD Candidate, Health Sciences Centre; Eileen Britt, Senior Lecturer, Registered Clinical Psychologist, Department of Psychology/Health Sciences Centre; Mark Wallace-Bell, Lecturer, Health Sciences Centre; Shelley Johnson-Elsmore, Research Assistant, Health Sciences Centre; University of Canterbury, Christchurch

Acknowledgements

We thank the Partnership Health Organisation (PHO) for supporting this research by providing funding for a summer scholarship. In addition we thank the CDHB and Diabetes Centre staff for facilitating the study procedures, in particular Kit Hoeben, Diabetes Centre Manager.

Correspondence

Dr Eileen Britt, Health Sciences Centre, University of Canterbury, Private Bag 4800, Christchurch, New Zealand. Fax: +64 (0)3 3643318

Correspondence Email

eileen.britt@canterbury.ac.nz

Competing Interests

None.

Couper J. Children with type 1 diabetes: Where are we at? Med J Aust 2002; 177:228-9.Buckloh L, Lochrie A, Antal H, et al. Diabetes complications in youth: Qualitative analysis of parents' perspectives of family learning and knowledge. Diabetes Care 2008;31:1516-20.Lunt H, Moore MP, Kendall D, et al. Prevalence of microvascular complications in adolescents with Type 1 diabetes. Diabet Med 2003;20:421-2.DCCT Research Group. The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulin-dependent diabetes mellitus. The Diabetes Control and Complications Trial Research Group. N Engl J Med 1993;329:977-86.Wild S, Roglic G, Green A, et al. Global prevalence of diabetes: Estimates for the year 2000 and projections for 2030. Diabetes Care 2004;27:1047.Willis JA, Scott RS, Darlow BA, et al. Incidence of type 1 diabetes mellitus diagnosed before age 20 years in Canterbury, New Zealand over the last 30 years. J Pediatr Endocrinol Metab 2002;15:637-43.Onkamo P, Vaananen S, Karvonen M, Tuomilehto J. Worldwide increase in incidence of Type I diabetes--the analysis of the data on published incidence trends. Diabetologia 1999;42:1395-403.Wu D, Kendall D, Lunt H, et al. Prevalence of Type 1 diabetes in New Zealanders aged 0-24 years. N Z Med J 2005;118:U1557. http://journal.nzma.org.nz/journal/118-1218/1557/content.pdfStatistics New Zealand. Street Links. http://www.stats.govt.nz/browse_for_stats/people_and_communities/geographic-areas/streetlink.aspxStatistics New Zealand. The 2006 population census: District Health Board Area summary tables.http://www.stats.govt.nz/Census/about-2006-census/district-health-board-area-summary-tables.aspxStatistics New Zealand. Information by variable. http://www.stats.govt.nz/Census/about-2006-census/information-by-variable/ethnicity.aspx#1Lockhart RS. Introduction to statistics and data analysis for the behavioral sciences New York: W.H. Freeman; 1998.Confidence Interval for the difference between two proportions. http://www.stat.wmich.edu/s216/book/node85.htmlTandberg D. Confidence intervals difference between two proportions and Number Needed to Treat (NNT) Version 1.49.http://www.cebm.net/index.aspx?o=1061Statistics New Zealand. The 2001 population census: District Health Board Area summary tables.http://www.stats.govt.nz/tools_and_services/tools/TableBuilder/2001-population-census/top-40-tables.aspx

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contact nzmj@nzma.org.nz

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Type 1 diabetes is the most common endocrine disorder in children and adolescents.1 Type 1 diabetes in youth may have profound long-term complications, if poorly managed. Long-term complications may contribute to life-lasting disabilities and chronic diseases, such as blindness, kidney failure, nerve damage, circulatory problems, heart disease, and early death.2,3The onset of long-term complications can be prevented or delayed if good diabetes management is achieved,4 thereby reducing the costs for the individual and their family, and to the healthcare system.The incidence and prevalence of type 1 diabetes is increasing nationally and internationally.5-7For example, over a 30-year period in the Canterbury geographical region, the incidence of type 1 diabetes in children and adolescents (0-19 years) was found to have significantly increased with time.6The incidence rate of type 1 diabetes over time was significant in children (0-14 year olds).6Whereas there were insignificant changes in the rate of new presentations of type 1 diabetes with time in adolescents (15-19 year olds).6 The last study of the prevalence of type 1 diabetes in youth (0-24 year olds) in the Canterbury District Health Board (CDHB) indicated a prevalence of 227 per 100,000 population.8 The present study provides up-to-date data on the number and prevalence of youth with type 1 diabetes. The aims of this paper were to Describe the demographics of youth (15-24 year olds) with type 1 diabetes in the CDHB catchment area and to compare this data with previous research.8 Calculate the prevalence of youth with type 1 diabetes in the CDHB catchment area. Investigate whether there has been an increase in the prevalence of youth with type 1 diabetes residing within the CDHB catchment area. Methods The study comprised two main phases - data collection and data analysis. The project involved collating information for youth with type 1 diabetes aged between 15 and 24 years, residing within the CDHB catchment area. This included Christchurch, the town of Ashburton, and Northern rural Canterbury. South Canterbury District Health Board (SCDHB) entries were excluded from the study. The number of youth residing in the identified catchment area based on an anchor date of 1 November 2010 was calculated. This date was aligned with the previous study's anchor date,8yielding a 7-year gap between the two studies. The search criteria (i.e. valid entries) used in the previous study was followed.8 Thus, those with newly diagnosed and patients with secondary or type 2 diabetes were excluded from the study. CDHB records were searched in multiple electronic and physical sources. The electronic data sources included the CDHB inpatient and outpatients lists; the Diabetes Youth Canterbury database; and records from the previous study.8 The data collected comprised descriptive information and demographic characteristics of the youth. This included gender, ethnicity, age, residential area deprivation level,9 and diabetes duration. Missing data-point entries were updated by searching the physical files held at the CDHB Diabetes Centre based on the National Health Index (NHI), and contacting the individual youth's General Practitioner (GP). The collated data was entered in raw format using Microsoft Excel 2007 and IBM Statistical Package for Social Sciences (IBM SPSS 19). These software packages were used in the first (data collection) and second (data analysis) phases of the study. Age data was divided into two age bands (15-19 years and 20-24 years), representing adolescents and young adult developmental stages. In the second phase, the prevalence of youth with type 1 diabetes was calculated, and then this was compared to the results of the last audit's study that was conducted in the CDHB in 2003.8 In the present research, the prevalence calculation was based on the 2006 census data, whereas the 2003 prevalence calculation was based on the 2001 census data.10 Prior to comparing the two results, the studies populations were checked for adequate comparability. The checking for this revealed two potential points of difference. The first potential point of difference point was related to maintaining the unity of the source of the obtained census lists. It was established that both of the census population figures were drawn from the same source of either Total Responses or Prioritised lists.11 The second point was related to the different data collection and entry system of the 2001 and the 2006 census. For example, the ‘New Zealander' entry was grouped with the European entry in the 2001 census data; however, in 2006 a separate classification under ‘other ethnicities' was created to sum the New Zealander entries.11 To overcome this issue, the total number of the New Zealander subcategory in the 2006 census data was added to total number of the European category, thus making the 2001 and 2006 census population totals comparable to each other. After ensuring the populations comparability, the 2010 and 2003 prevalences were compared. This process involved calculating the difference between the prevalences, and the 95% confidence interval (CI) of this difference.12-14 This difference was then statistically tested for significance.12-14 Results The number of youth with type 1 diabetes residing within the CDHB catchment area on the anchor date 1 November 2010 was 248. The demographics of these youth are depicted in Table 1. Table 1. Demographics of youth with type 1 diabetes, who are residing within the CDHB catchment area in 2010 Variables Count N% Gender Female 120 48.4% Male 128 51.6% Age groups* (years) (15-19) 131 52.8% (20-24) 117 47.2% Ethnicity European 227 91.5% Maori 9 3.6% Pacific Peoples 3 1.2% Other 9 3.6% Diabetes duration** (years) between 1 and 5 55 22.2% between 6 and 10 82 33.1% between 11 and 15 68 27.4% between 16 and 20 33 13.3% more than 20 10 4.0% Deprivation quintiles (1 = least deprived areas) 1 77 31.2% 2 55 22.3% 3 55 22.3% 4 35 14.2% 5 25 10.1% * Mean age was 19.2 years old (standard deviation (std. dev.) =2.6 years) ** Mean length of diagnosis was 10 years (std. dev. =5.4 years; minimum =0.9 year (11 months); maximum=22 years). The prevalence calculation only included entries of established diabetes. This included diabetes duration that is around 1 year or more. Based on the total number of youth with type 1 diabetes residing within the CDHB catchment area in 2010, the prevalence was calculated using the 2006 census data.10 The calculation was stratified according to ethnicity. Additionally, the European ethnic group had sufficient numbers to allow for the stratifying of data into two age bands (15-19 years and 20-24 years), which correspond to the census age categories. The results are shown in Table 2. Table 2. Number and prevalence of European New Zealanders with type 1 diabetes (stratified by age) residing in the Canterbury District Health Board Catchment Area in 2010 and 2003 Anchor date (15-19 years old) (20-24 years old) Total 1 November 2010 Number 126 101 227 Prevalence per 100,000 (95%CI X to Y) 443 (372 to 527) 406 (334 to 493) 426 (374 to 484) Total population10 28,452 24,891 53,343 Anchor date 1 November 2003 (15-19 years old) (20-24 years old) Total Number8 92 95 187 Prevalence per 100,000 (95%CI X-Y) 369 (301 to 452) 394 (322 to 481) 381 (330 to 440) Total population15 24,951 24,126 49,077 The total prevalence from the present study was compared with the prevalence obtained by the previous study (Table 2),8 after ensuring the comparability of data as previously described. The comparison yielded an increase of 45 per 100,000 (12%)population. However, the 95% confidence interval for this prevalence difference ranged from -33 to +122 indicating that this increase was not statistically significant. From 2003 to 2010 there was a prevalence increase of 74 per 100,000 (20%) in adolescents (15 to 19 year olds), and 12 per 100,000 (3%) in young adults (20 to 24 year olds) with type 1 diabetes. However, the prevalence increase was statistically insignificant in each age band, from 2003 to 2010, according to the confidence interval of the difference: (95%CI -35 to 182) and (95%CI -101 to 125) per 100,000 adolescents and young adults, respectively. Comparing the total populations in Table 2 suggests that the adolescents' age band had an increase of 14% compared to a 3% increase in the young adults' total population.

Summary

Abstract

Aim

The aim of the present study was to provide up-to-date descriptive information in relation to youth (15-24 years) with type 1 diabetes, residing within the Canterbury District Health Board (CDHB) catchment area. This included calculating the prevalence of type 1 diabetes in youth, and investigating whether there was an increase in the prevalence since a previous study reporting the prevalence of type 1 diabetes in youth in the CDHB in 2003.

Method

Data were collected from multiple clinical and research sources. Descriptive information and emographic characteristics, including age, gender, ethnicity, deprivation level, and diabetes duration were gathered. The prevalence, stratified by age and ethnicity, was calculated using the 2006 population census data.

Results

There were 248 people with type 1 diabetes aged between 15 and 24 years residing within the CDHB area at the time of present study, giving a prevalence of 426 per 100,000 European youth with type 1 diabetes. The prevalence is found to have increased by 45 per 100,000 (12%) since 2003, but was statistically insignificant.

Conclusion

There was no statistically significant increase in the prevalence of type 1 diabetes in youth in the CDHB catchment area between 2003 and 2010. However, the absolute figures of adolescents and young adults with type 1 diabetes have increased, which implies an increased demand on health care associated with diabetes compared to 7 years ago.

Author Information

Balsam Obaid, PhD Candidate, Health Sciences Centre; Eileen Britt, Senior Lecturer, Registered Clinical Psychologist, Department of Psychology/Health Sciences Centre; Mark Wallace-Bell, Lecturer, Health Sciences Centre; Shelley Johnson-Elsmore, Research Assistant, Health Sciences Centre; University of Canterbury, Christchurch

Acknowledgements

We thank the Partnership Health Organisation (PHO) for supporting this research by providing funding for a summer scholarship. In addition we thank the CDHB and Diabetes Centre staff for facilitating the study procedures, in particular Kit Hoeben, Diabetes Centre Manager.

Correspondence

Dr Eileen Britt, Health Sciences Centre, University of Canterbury, Private Bag 4800, Christchurch, New Zealand. Fax: +64 (0)3 3643318

Correspondence Email

eileen.britt@canterbury.ac.nz

Competing Interests

None.

Couper J. Children with type 1 diabetes: Where are we at? Med J Aust 2002; 177:228-9.Buckloh L, Lochrie A, Antal H, et al. Diabetes complications in youth: Qualitative analysis of parents' perspectives of family learning and knowledge. Diabetes Care 2008;31:1516-20.Lunt H, Moore MP, Kendall D, et al. Prevalence of microvascular complications in adolescents with Type 1 diabetes. Diabet Med 2003;20:421-2.DCCT Research Group. The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulin-dependent diabetes mellitus. The Diabetes Control and Complications Trial Research Group. N Engl J Med 1993;329:977-86.Wild S, Roglic G, Green A, et al. Global prevalence of diabetes: Estimates for the year 2000 and projections for 2030. Diabetes Care 2004;27:1047.Willis JA, Scott RS, Darlow BA, et al. Incidence of type 1 diabetes mellitus diagnosed before age 20 years in Canterbury, New Zealand over the last 30 years. J Pediatr Endocrinol Metab 2002;15:637-43.Onkamo P, Vaananen S, Karvonen M, Tuomilehto J. Worldwide increase in incidence of Type I diabetes--the analysis of the data on published incidence trends. Diabetologia 1999;42:1395-403.Wu D, Kendall D, Lunt H, et al. Prevalence of Type 1 diabetes in New Zealanders aged 0-24 years. N Z Med J 2005;118:U1557. http://journal.nzma.org.nz/journal/118-1218/1557/content.pdfStatistics New Zealand. Street Links. http://www.stats.govt.nz/browse_for_stats/people_and_communities/geographic-areas/streetlink.aspxStatistics New Zealand. The 2006 population census: District Health Board Area summary tables.http://www.stats.govt.nz/Census/about-2006-census/district-health-board-area-summary-tables.aspxStatistics New Zealand. Information by variable. http://www.stats.govt.nz/Census/about-2006-census/information-by-variable/ethnicity.aspx#1Lockhart RS. Introduction to statistics and data analysis for the behavioral sciences New York: W.H. Freeman; 1998.Confidence Interval for the difference between two proportions. http://www.stat.wmich.edu/s216/book/node85.htmlTandberg D. Confidence intervals difference between two proportions and Number Needed to Treat (NNT) Version 1.49.http://www.cebm.net/index.aspx?o=1061Statistics New Zealand. The 2001 population census: District Health Board Area summary tables.http://www.stats.govt.nz/tools_and_services/tools/TableBuilder/2001-population-census/top-40-tables.aspx

For the PDF of this article,
contact nzmj@nzma.org.nz

View Article PDF

Type 1 diabetes is the most common endocrine disorder in children and adolescents.1 Type 1 diabetes in youth may have profound long-term complications, if poorly managed. Long-term complications may contribute to life-lasting disabilities and chronic diseases, such as blindness, kidney failure, nerve damage, circulatory problems, heart disease, and early death.2,3The onset of long-term complications can be prevented or delayed if good diabetes management is achieved,4 thereby reducing the costs for the individual and their family, and to the healthcare system.The incidence and prevalence of type 1 diabetes is increasing nationally and internationally.5-7For example, over a 30-year period in the Canterbury geographical region, the incidence of type 1 diabetes in children and adolescents (0-19 years) was found to have significantly increased with time.6The incidence rate of type 1 diabetes over time was significant in children (0-14 year olds).6Whereas there were insignificant changes in the rate of new presentations of type 1 diabetes with time in adolescents (15-19 year olds).6 The last study of the prevalence of type 1 diabetes in youth (0-24 year olds) in the Canterbury District Health Board (CDHB) indicated a prevalence of 227 per 100,000 population.8 The present study provides up-to-date data on the number and prevalence of youth with type 1 diabetes. The aims of this paper were to Describe the demographics of youth (15-24 year olds) with type 1 diabetes in the CDHB catchment area and to compare this data with previous research.8 Calculate the prevalence of youth with type 1 diabetes in the CDHB catchment area. Investigate whether there has been an increase in the prevalence of youth with type 1 diabetes residing within the CDHB catchment area. Methods The study comprised two main phases - data collection and data analysis. The project involved collating information for youth with type 1 diabetes aged between 15 and 24 years, residing within the CDHB catchment area. This included Christchurch, the town of Ashburton, and Northern rural Canterbury. South Canterbury District Health Board (SCDHB) entries were excluded from the study. The number of youth residing in the identified catchment area based on an anchor date of 1 November 2010 was calculated. This date was aligned with the previous study's anchor date,8yielding a 7-year gap between the two studies. The search criteria (i.e. valid entries) used in the previous study was followed.8 Thus, those with newly diagnosed and patients with secondary or type 2 diabetes were excluded from the study. CDHB records were searched in multiple electronic and physical sources. The electronic data sources included the CDHB inpatient and outpatients lists; the Diabetes Youth Canterbury database; and records from the previous study.8 The data collected comprised descriptive information and demographic characteristics of the youth. This included gender, ethnicity, age, residential area deprivation level,9 and diabetes duration. Missing data-point entries were updated by searching the physical files held at the CDHB Diabetes Centre based on the National Health Index (NHI), and contacting the individual youth's General Practitioner (GP). The collated data was entered in raw format using Microsoft Excel 2007 and IBM Statistical Package for Social Sciences (IBM SPSS 19). These software packages were used in the first (data collection) and second (data analysis) phases of the study. Age data was divided into two age bands (15-19 years and 20-24 years), representing adolescents and young adult developmental stages. In the second phase, the prevalence of youth with type 1 diabetes was calculated, and then this was compared to the results of the last audit's study that was conducted in the CDHB in 2003.8 In the present research, the prevalence calculation was based on the 2006 census data, whereas the 2003 prevalence calculation was based on the 2001 census data.10 Prior to comparing the two results, the studies populations were checked for adequate comparability. The checking for this revealed two potential points of difference. The first potential point of difference point was related to maintaining the unity of the source of the obtained census lists. It was established that both of the census population figures were drawn from the same source of either Total Responses or Prioritised lists.11 The second point was related to the different data collection and entry system of the 2001 and the 2006 census. For example, the ‘New Zealander' entry was grouped with the European entry in the 2001 census data; however, in 2006 a separate classification under ‘other ethnicities' was created to sum the New Zealander entries.11 To overcome this issue, the total number of the New Zealander subcategory in the 2006 census data was added to total number of the European category, thus making the 2001 and 2006 census population totals comparable to each other. After ensuring the populations comparability, the 2010 and 2003 prevalences were compared. This process involved calculating the difference between the prevalences, and the 95% confidence interval (CI) of this difference.12-14 This difference was then statistically tested for significance.12-14 Results The number of youth with type 1 diabetes residing within the CDHB catchment area on the anchor date 1 November 2010 was 248. The demographics of these youth are depicted in Table 1. Table 1. Demographics of youth with type 1 diabetes, who are residing within the CDHB catchment area in 2010 Variables Count N% Gender Female 120 48.4% Male 128 51.6% Age groups* (years) (15-19) 131 52.8% (20-24) 117 47.2% Ethnicity European 227 91.5% Maori 9 3.6% Pacific Peoples 3 1.2% Other 9 3.6% Diabetes duration** (years) between 1 and 5 55 22.2% between 6 and 10 82 33.1% between 11 and 15 68 27.4% between 16 and 20 33 13.3% more than 20 10 4.0% Deprivation quintiles (1 = least deprived areas) 1 77 31.2% 2 55 22.3% 3 55 22.3% 4 35 14.2% 5 25 10.1% * Mean age was 19.2 years old (standard deviation (std. dev.) =2.6 years) ** Mean length of diagnosis was 10 years (std. dev. =5.4 years; minimum =0.9 year (11 months); maximum=22 years). The prevalence calculation only included entries of established diabetes. This included diabetes duration that is around 1 year or more. Based on the total number of youth with type 1 diabetes residing within the CDHB catchment area in 2010, the prevalence was calculated using the 2006 census data.10 The calculation was stratified according to ethnicity. Additionally, the European ethnic group had sufficient numbers to allow for the stratifying of data into two age bands (15-19 years and 20-24 years), which correspond to the census age categories. The results are shown in Table 2. Table 2. Number and prevalence of European New Zealanders with type 1 diabetes (stratified by age) residing in the Canterbury District Health Board Catchment Area in 2010 and 2003 Anchor date (15-19 years old) (20-24 years old) Total 1 November 2010 Number 126 101 227 Prevalence per 100,000 (95%CI X to Y) 443 (372 to 527) 406 (334 to 493) 426 (374 to 484) Total population10 28,452 24,891 53,343 Anchor date 1 November 2003 (15-19 years old) (20-24 years old) Total Number8 92 95 187 Prevalence per 100,000 (95%CI X-Y) 369 (301 to 452) 394 (322 to 481) 381 (330 to 440) Total population15 24,951 24,126 49,077 The total prevalence from the present study was compared with the prevalence obtained by the previous study (Table 2),8 after ensuring the comparability of data as previously described. The comparison yielded an increase of 45 per 100,000 (12%)population. However, the 95% confidence interval for this prevalence difference ranged from -33 to +122 indicating that this increase was not statistically significant. From 2003 to 2010 there was a prevalence increase of 74 per 100,000 (20%) in adolescents (15 to 19 year olds), and 12 per 100,000 (3%) in young adults (20 to 24 year olds) with type 1 diabetes. However, the prevalence increase was statistically insignificant in each age band, from 2003 to 2010, according to the confidence interval of the difference: (95%CI -35 to 182) and (95%CI -101 to 125) per 100,000 adolescents and young adults, respectively. Comparing the total populations in Table 2 suggests that the adolescents' age band had an increase of 14% compared to a 3% increase in the young adults' total population.

Summary

Abstract

Aim

The aim of the present study was to provide up-to-date descriptive information in relation to youth (15-24 years) with type 1 diabetes, residing within the Canterbury District Health Board (CDHB) catchment area. This included calculating the prevalence of type 1 diabetes in youth, and investigating whether there was an increase in the prevalence since a previous study reporting the prevalence of type 1 diabetes in youth in the CDHB in 2003.

Method

Data were collected from multiple clinical and research sources. Descriptive information and emographic characteristics, including age, gender, ethnicity, deprivation level, and diabetes duration were gathered. The prevalence, stratified by age and ethnicity, was calculated using the 2006 population census data.

Results

There were 248 people with type 1 diabetes aged between 15 and 24 years residing within the CDHB area at the time of present study, giving a prevalence of 426 per 100,000 European youth with type 1 diabetes. The prevalence is found to have increased by 45 per 100,000 (12%) since 2003, but was statistically insignificant.

Conclusion

There was no statistically significant increase in the prevalence of type 1 diabetes in youth in the CDHB catchment area between 2003 and 2010. However, the absolute figures of adolescents and young adults with type 1 diabetes have increased, which implies an increased demand on health care associated with diabetes compared to 7 years ago.

Author Information

Balsam Obaid, PhD Candidate, Health Sciences Centre; Eileen Britt, Senior Lecturer, Registered Clinical Psychologist, Department of Psychology/Health Sciences Centre; Mark Wallace-Bell, Lecturer, Health Sciences Centre; Shelley Johnson-Elsmore, Research Assistant, Health Sciences Centre; University of Canterbury, Christchurch

Acknowledgements

We thank the Partnership Health Organisation (PHO) for supporting this research by providing funding for a summer scholarship. In addition we thank the CDHB and Diabetes Centre staff for facilitating the study procedures, in particular Kit Hoeben, Diabetes Centre Manager.

Correspondence

Dr Eileen Britt, Health Sciences Centre, University of Canterbury, Private Bag 4800, Christchurch, New Zealand. Fax: +64 (0)3 3643318

Correspondence Email

eileen.britt@canterbury.ac.nz

Competing Interests

None.

Couper J. Children with type 1 diabetes: Where are we at? Med J Aust 2002; 177:228-9.Buckloh L, Lochrie A, Antal H, et al. Diabetes complications in youth: Qualitative analysis of parents' perspectives of family learning and knowledge. Diabetes Care 2008;31:1516-20.Lunt H, Moore MP, Kendall D, et al. Prevalence of microvascular complications in adolescents with Type 1 diabetes. Diabet Med 2003;20:421-2.DCCT Research Group. The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulin-dependent diabetes mellitus. The Diabetes Control and Complications Trial Research Group. N Engl J Med 1993;329:977-86.Wild S, Roglic G, Green A, et al. Global prevalence of diabetes: Estimates for the year 2000 and projections for 2030. Diabetes Care 2004;27:1047.Willis JA, Scott RS, Darlow BA, et al. Incidence of type 1 diabetes mellitus diagnosed before age 20 years in Canterbury, New Zealand over the last 30 years. J Pediatr Endocrinol Metab 2002;15:637-43.Onkamo P, Vaananen S, Karvonen M, Tuomilehto J. Worldwide increase in incidence of Type I diabetes--the analysis of the data on published incidence trends. Diabetologia 1999;42:1395-403.Wu D, Kendall D, Lunt H, et al. Prevalence of Type 1 diabetes in New Zealanders aged 0-24 years. N Z Med J 2005;118:U1557. http://journal.nzma.org.nz/journal/118-1218/1557/content.pdfStatistics New Zealand. Street Links. http://www.stats.govt.nz/browse_for_stats/people_and_communities/geographic-areas/streetlink.aspxStatistics New Zealand. The 2006 population census: District Health Board Area summary tables.http://www.stats.govt.nz/Census/about-2006-census/district-health-board-area-summary-tables.aspxStatistics New Zealand. Information by variable. http://www.stats.govt.nz/Census/about-2006-census/information-by-variable/ethnicity.aspx#1Lockhart RS. Introduction to statistics and data analysis for the behavioral sciences New York: W.H. Freeman; 1998.Confidence Interval for the difference between two proportions. http://www.stat.wmich.edu/s216/book/node85.htmlTandberg D. Confidence intervals difference between two proportions and Number Needed to Treat (NNT) Version 1.49.http://www.cebm.net/index.aspx?o=1061Statistics New Zealand. The 2001 population census: District Health Board Area summary tables.http://www.stats.govt.nz/tools_and_services/tools/TableBuilder/2001-population-census/top-40-tables.aspx

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