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| Journal of the New Zealand Medical Association,
23-July-2004, Vol 117 No 1198
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|
 THE
NEW ZEALAND
MEDICAL JOURNAL Vol 117 No 1198 ISSN 1175 8716
Trends and patterns of avoidable hospitalisations in New
Zealand: 1980–1997
Arunachalam Dharmalingam, Ian Pool, Sandra Baxendine, Janet
Sceats
New Zealand’s health system has gone through major
reforms over the last two decades, particularly in the
1990s.1-3 The health reforms have occurred in
the context of major restructuring of the economy and the social
sectors.4-5 The direct impact of the health
reforms is on the supply of health services: availability of (and accessibility
to) primary care. The reforms can influence the level of avoidable
hospitalisations by limiting the availability and affordability of primary care.
Evidence from both overseas and New Zealand suggests that
there is a strong link between avoidable hospitalisations and the
underutilisation of primary care, and that underutilisation is associated with
lower socioeconomic status.6–13
Several studies have shown that (with timely and adequate
primary care) it is possible to prevent the onset of illness and control an
acute episode; chronic conditions can also be monitored and managed with access
to appropriate primary care.7,11,12,14-19 In
this paper, we describe the trends in (and pattern of) hospitalisations for
conditions that could potentially be taken care of by the provision of (and
access to) adequate primary care. We describe the regional differentials, age
patterns, and disease patterns in avoidable hospitalisations between 1980 and
1997. We then discuss the findings in the context of the changing health sectors
of the 1980s and early 1990s.
Data and methodsWe use public hospital
inpatient discharges data obtained from the New Zealand Health Information
Service for the calendar years 1980–1997. To allow for time series
analysis, the data were adjusted for changes to data collection and coding
procedures and health policy. Katzenellenbogen et
al20 have recently documented that a number of
health policy and other changes have affected the comparability of discharge
data for the period since 1980. They also ‘filtered’ the data by
excluding a number of categories, so that valid comparisons could be made over
time.21 We have adopted Katzenellenbogen et
al’s suggestions, and (accordingly) excluded several categories (including
day-patients, as definitions differed over time) from the discharge data set
used here.
Several overlapping lists of avoidable hospitalisations
are available in the literature. In general, avoidable hospitalisations are
defined as those resulting from medical conditions that can be prevented,
controlled, monitored, and managed by timely and effective primary
care.6,8,12,19 Following Jackson et
al,10,11 in this paper we consider the
hospitalisations for medical conditions given in Table 1, as
avoidable.
Table 1. Avoidable hospitalisation (AH) conditions with
ICD-9-CM codes
We derived avoidable hospitalisation rates for each of
the four time points around the 1981, 1986, 1991, and 1996 censuses. We first
computed a 3-year moving average for the number of avoidable hospitalisations
and then divided this figure by the census population to obtain the rates for
the four periods: 1980–82, 1985–87, 1990–92, and 1995-97. We
computed avoidable hospitalisation rates by gender, functional age groups, and
medical condition for New Zealand (as a whole and for 29 geographic regions).
The most recent health reforms have reorganised the New
Zealand health sector into 21 District Health Boards (DHB). As some DHBs have a
much bigger population or geographical spread than others, for the purpose this
paper we divided the bigger ones into smaller units to give a total of 29
regions. Of the 29 regions, 12 regions had a population of less than 100,000 in
1996, 14 regions had a population between 100,000 and 200,000, and 3 regions had
a population over 200,000 people in 1996.
All the rates presented here are standardised for age
compositional differences, using the 1996 New Zealand age-composition as the
standard. This is important because the demographic composition of a population
can not only change over time but can also differ between various geographic
regions.
To study the regional differences in avoidable
hospitalisations, we derived relative hospitalisation rates for each region by
using North Shore as the reference population. North Shore was chosen as it had
one of the lowest avoidable hospitalisation rates among the 29 regions. North
Shore is also a region that has fared well in many socioeconomic indicators.
Relative avoidable hospitalisation rate is obtained by dividing the
age-standardised avoidable hospitalisation rate for a given region and year by
the age-standardised avoidable hospitalisation rate for North Shore for the same
year.
We use the proportion of sole Maori population (the
indigenous people of New Zealand) in a region as a proxy for socioeconomic
status. There is a large body of empirical literature that shows that Maori
ethnicity is strongly associated with poor socioeconomic
status.22-27
In New Zealand censuses since 1986, the ethnicity
question has been based on self-identification, and individuals can report more
than one ethnicity. Sole Maori are those who identify Maori as their only ethnic
group. Until the 1981 census, ethnicity classification was based on a biological
criterion: all those with half or more Maori blood were classified as Maori.
Moreover, until 1996 people could report only one
ethnicity in hospitalisation records. The inconsistencies, in the definition and
collection of ethnicity data between the censuses (that provide the denominator
data) and hospitalisation records, could lead to underestimation or
overestimation of hospitalisation rates among the Maori—depending on
whether sole Maori or mixed Maori population is used in the
denominator.28-30 Thus we decided not to derive
hospitalisation rates by ethnicity.
We also considered the proportion of population
receiving welfare benefits in a region and the proportions without any
educational qualifications as regional level socioeconomic indicators. But this
information was not comparable over the time period under consideration. For
instance, ACC was only included in the benefit data from 1991; ‘no
educational qualifications’ data was also problematic because there was a
‘still at school category’ in 1981, 1986, and 1991
censuses—but not in the 1996 census.
We did not have access to the
NZdep data (aggregate area level
composite measure of deprivation derived from the census based on a number of
socioeconomic indicators) but again they are available only for 1991 and 1996
censuses. Thus we decided to use the proportion of sole Maori as an indicator
for the relative socioeconomic position of a region. The correlation analysis
(results not given) showed that the proportion of sole Maori in a region was
strongly associated with the proportion on welfare benefits (for all but
1980–82 period) and the proportion with no educational qualifications.
Although the ethnicity questions in the census have
changed over time, data on sole Maori obtained since the 1986 census (based on
sociocultural definition) are comparable with the data from the 1981 census
(based on blood-fraction
definition).28,29
ResultsAge standardised avoidable
hospitalisation rates (AHR) are given in Table 2 for the period 1980–97 by
geographic regions. For New Zealand (as a whole), the rate increased from 73 per
10,000 people in 1980–82, to 83 in 1985–87, and to 96 in
1995–97.
Table 2. Age-standardised avoidable hospitalisation
rates per 10,000 population in New Zealand
This amounts to an increase of about 32% between 1980 and
1997. This increase was punctuated by a decline between 1985–87 and
1990–92. The rates for males and females followed a similar trend. Males
have a higher AHR than females, and the male-female difference seems to have
narrowed: the difference declined from about 16 per 10,000 people in the 1980s
to about 14 in 1995–97. There was a substantial geographical variation in
the level of avoidable hospitalisation—over the 1980–97 period, some
regions experienced greater increases in AHRs than others.
While most regions showed decline in the rate of
hospitalisations between 1985–87 and 1990–92, nine regions showed
monotonic increase during 1980–97. These regions are: Northland, Central
Waikato, Eastern Bay of Plenty, Lakes, Tairawhiti, Wanganui, Southland, Rodney,
and Waitakere. Incidentally, all but Southland, Rodney and Waitakere have a
significant rural and sole Maori population. Tairawhiti, a region with over
one-third of its population in 1991 being sole Maori, had the highest rate of
avoidable hospitalisations since the mid-1980s.
The relative avoidable hospitalisation rates (RAHR) for the
29 regions are given in Table 3. As North Shore had one of the lowest avoidable
hospitalisation rates since 1980, it was chosen as the reference region to
derive the RAHRs. The pattern and trends in the relative rates help illustrate
how the different regions have experienced avoidable hospitalisations relative
to a relatively better off region, North Shore.
It is clear from Table 3 that in 1980–82 there were
about 13 regions whose rates were over two times as much as the rate observed
for North Shore. This declined to six regions in 1985–87, to four regions
in 1990–92, and to only one region in 1995–97. This underscores the
fact that (over time) the various regions have tended to converge towards the
rates observed in North Shore.
There is also a strong socioeconomic gradient to the
regional pattern in avoidable hospitalisations. In general, regions with higher
avoidable hospitalisation rates have tended to have a greater proportion of sole
Maori populations. In 1995-97, Eastern Bay of Plenty and Tairawhiti were the
only regions that had rates about twice the rate observed in North Shore. These
two regions also had the highest proportion of sole Maori population (about 35%
in 1991 census). This is further supported by the simple regression estimates
given in Table 4: the proportion of Sole Maori population in a region is a
powerful predictor of the avoidable hospitalisation rates.
In the 1990s, over 80% of the regional variations in
avoidable hospitalisation rate is explained by the regional variations in the
proportion of sole Maori populations. We also considered including two
additional variables in the regression model: proportion of population on
benefits (unemployment, domestic purposes benefit (DPB), and sickness/invalid
benefit) and proportion with no educational qualifications. But we did not
include them because, as discussed above, the data on these two indicators were
not comparable for the periods. Moreover, these two variables were very strongly
associated with proportion of sole Maori population. This association suggests
that ethnicity is probably a reliable marker of socioeconomic deprivation,
including inequalities in education and employment.
Table 3. Relative avoidable hospitalisations in New
Zealand (relative to North Shore region)
Age-standardised total hospitalisation rates (including
avoidable and non-avoidable hospitalisations) showed that (tables not included)
there was an overall decline between 1980–82 and
1995–97—although there was a slight increase between 1990–92
and 1995–97. The time trend in total hospitalisation rates is similar to
that of avoidable hospitalisation rates given in Tables 2 and 3, but in the
opposite direction. Again there was some regional variation.
Table 4. Parameter estimates from a simple regression
model for four periods in New Zealand
Note:
Age-standardised avoidable hospitalisation rate is the dependent variable;
proportion Sole Maori is the independent variable.
Although almost all regions (see Table 2) had experienced an
increase in avoidable hospitalisations between 1980–82 and 1995–97,
all but ten regions had a decrease in total hospitalisation rates during the
same period. Thus overall, the avoidable hospitalisation rates and total
hospitalisation rates moved in the opposite direction during 1980–97. As
with the relative avoidable hospitalisation rates, the variations in relative
total hospitalisation rates have tended to narrow over time. Thus a major change
in the level of total and avoidable hospitalisation rates is for regional
variations to narrow.
In Table 5, we provide the avoidable hospitalisation rates
as a percent of total hospitalisation rates for various regions. In
1995–97, about 1 in 10 hospitalisations were avoidable. For New Zealand
(as a whole), the avoidable as a percent of total hospitalisations has increased
from 7% in 1980–82 to 10%in 1995-97. Interestingly, there is no clear
socioeconomic gradient to the observed pattern in Table 4. This is likely to be
related to the regional variation in the direction of change in total and
avoidable hospitalisation rates over the time period (1980–97).
Rates of avoidable hospitalisations for seven broad age
groups are given in Table 6. The highest rate is observed for those aged 75+,
followed by the youngest population aged under 5 years. In 1995–97, the
avoidable hospitalisation rates were 409 per 10,000 population in the 75+ age
group, 228 in the under 5 age group, 180 in the 65–74 age group, and
between 45 and 75 in the 5–64 age groups.
As with the overall avoidable hospitalisation rates,
age-specific rates also showed an increase between 1980–82 and
1995–97. However, the rate of increase differed by age. While the rate
increased by 31% between 1980–82 and 1995–97 for the under 5 age
group, it did so by 51% among those aged 75 and over. The smallest increase (2%)
was observed for the 5–14 age group.
Table 5. Percentage of total hospitalisations that are
avoidable in New Zealand (for various regions)
Socioeconomic variations are also evident in the
age-specific rates for all the periods under consideration. But socioeconomic
differences seem to vary by age. For instance, in 1995-97, children aged under 5
years in regions with over 15% sole Maori population were about 37% more likely
to experience avoidable hospitalisations compared to children in regions with
less than 10% sole Maori population (see Figure 1). But among those aged 75+,
they were only 17% more likely to experience avoidable hospitalisation if they
lived in a region with over 15% sole Maori population than those living in a
region with under 10% sole Maori population.
Table 6. Age-specific
avoidable hospitalisation rates in New Zealand (per 10,000 people)
The avoidable hospitalisation rates as a proportion of total
hospitalisation rates for different age groups are given in Table 7. It is
interesting that the two youngest age groups (under 5, and 5–14) had the
highest levels: over 12% of all hospitalisations was avoidable. The 75+ age
group was the next highest. Thus not only that the level of avoidable
hospitalisation was one of the highest among children aged under 5 years, but
also the rate was higher in relation to total hospitalisation.
Table 7. Percent of total hospitalisations that are
avoidable in New Zealand (for various age groups)
In Table 8 we present the avoidable hospitalisation rates
for a number of primary care conditions (see Table 1 for a list of conditions).
We have followed Jackson et al10 in classifying
various diagnoses into a number of primary
conditions.6 It is clear from Table 8 that
people were more likely to be hospitalised for asthma, pneumonia, congestive
heart failure, and cellulitis than for any other avoidable conditions.
Table 8. Age-standardised avoidable hospitalisation
rates for various primary care conditions in New Zealand
In 1995–97, the avoidable hospitalisation rates for
asthma and pneumonia were the highest (over 250 per 100,000 people), followed by
congestive heart failure (173), and cellulitis (155). In terms of time trend, of
the four leading conditions of avoidable hospitalisation, all but asthma showed
a consistent increase between 1980–82 and 1995–97. In fact, the
increase was particularly dramatic between 1990–92 and 1995–96:
avoidable hospitalisation rate for cellulitis (a predominantly adult condition)
increased by 70%, by 62% for pneumonia and by 21% for congestive heart failure.
On the other hand, the rate for asthma decreased by 29%
between 1985-97 and 1995-97; as did the rate for immunisable conditions (by 34%
between 1985–87 and 1995–97), which (along with asthma) occur
predominantly among children.
Figure 2 shows the pattern of avoidable hospitalisation for
selected primary care conditions for three groups of regions—those with
under 10% sole Maori, between 10% and 14%, and those with over 15% sole Maori.
In general, for the four conditions shown in Figure 2, the
higher concentration of sole Maori populations is associated with higher
likelihood of avoidable hospitalisation. This was true for all the four time
points. What is also interesting to note from Figure 2 is that when we compare
the rates for asthma and pneumonia for the periods 1990–92 and
1995–97, while the socioeconomic differential seemed to narrow for asthma
between 1990-92 and 1995-97, it seems to have increased for pneumonia.
Figure
1. Age standardised avoidable hospitalisation rates for four major conditions
for three groups of regions in New Zealand (Sole Maori under 10%, 10-14%, and
15+%)
Figure 2. Age standardised avoidable hospitalisation
rates for four major conditions for three groups of regions in New Zealand (sole
Maori under 10%, 10-14%, and 15+%)
DiscussionThe analysis has shown that the
rate of avoidable hospitalisations has increased between the early 1980s and
mid-1990s. But there was a decline in avoidable hospitalisations between the
mid- and late-1980s. This period coincided with the first major health reforms
(1983–1991). Fourteen locally elected Area Health Boards were formed
during this period with the aim of improving efficiency and accountability. The
boards were given the responsibilities for health promotion, disease prevention,
and provision of personal treatment and caring
services.2,31
Although, it was criticised that there was no incentive for
the health boards to be efficient and that they suffered from weak
accountability,32 some area health boards did
make efforts to strengthen the primary care system. In order to improve access
to primary care, subsidies to general practitioner services were
increased.3 The decrease in avoidable
hospitalisation between 1985–87 and 1990–92 might have been partly
due to the changes effected by primary care initiatives of the area health
boards.
The increase in avoidable hospitalisations between
1990–92 and 1995–97 is likely to be associated with the radical
health reforms introduced in 1991 but came into effect in
1993.1-3,11,33-36 The main features of the 1993
reforms included: the separation of the funding, purchasing and provision of
health services with a view to encourage competition, and market behaviour in
the health sector.
Although there was no formal evaluation of the impact of the
reforms on the utilisation of health services, it has been argued that the
reforms were likely to have had the deleterious effect of severely limiting
access to primary care. This was not only due to the increases in fees for
general practitioner services but also due to welfare cuts which affected the
ability to access health services.37,38 This
was the case at least until the end of 1996 when the new Coalition Government
significantly modified the 1993
reforms.33,39-41
Although community service cards were introduced for
low-income groups as part of the health reforms to enable access to healthcare,
recent studies showed that the disadvantaged groups are still likely to
underutilise primary care.42-47
Another interesting result was the narrowing of the regional
disparities in avoidable hospitalisations between 1980 and 1997. Perhaps this is
linked to the change over to population-based funding for the provision of
health services beginning with the introduction of area health boards in the
mid-1980s. This formula is based on the age/gender composition of a health area
and is adjusted for the proportion of low-income
households.48 The reduction in regional
inequalities in the levels of hospitalisations (both avoidable and
non-avoidable) could be one of the beneficial impacts of the health
reforms.
Although the proportion of sole Maori population in a region
is not necessarily a perfect measure of relative deprivation of a region (as a
reviewer pointed out, this factor is likely to be confounded in the analysis
with the number of GPs in a region), our analysis has shown that it is a good
predictor of the level of avoidable hospitalisations. It is well established
that regions with high Maori population are more likely to have higher
proportion with no educational qualification, higher level of unemployment, poor
housing, higher proportion of sole parents, and higher proportion on welfare
benefits.49
Several studies have also shown that poor socioeconomic
status is associated with underutilisation of primary
care.1,10,11,16,47,50-53 Although financial
barriers are critical, non-monetary factors such as transport and geography may
also play a role in the poor utilisation of primary
care.17
It is suggested that the ‘lack of purpose in
life’ among the less educated and unemployed could be factor for poor
utilisation.54,17 It may be necessary for the
primary health care professionals to develop trusting relationship with the
patients to motivate those who have lost purpose in life. However, developing a
trusting relationship is difficult when faced with a higher patient to doctor
ratios.54,43
Moreover, it is argued that the primary care clinicians
‘do not use community-based information to organise the content of the
medical care they deliver’; rather ‘they often use practice-based
data to plan for the delivery of
services’.46 Access to primary care is
also limited by the uneven distribution of general practitioners across the
geographical regions. Despite substantial increases in the number of general
practitioners in New Zealand, maldistribution continues to be a perennial
issue.42
Since the 1993 reforms, there have been two re-reforms in
1996 and 1999.2 The late 1990s reforms have
tried to allow greater community participation in health sector decision-making
and replace ‘competition’ with
‘collaboration’.1,2,33,34,39-41 The
‘re-reforms’ (underpinned by greater emphasis on equity, social
justice, and community voice in decision-making) have the potential to reduce
the cost of healthcare and improve the quality of life by increasing access to
good primary care and reducing avoidable hospitalisations.
Author information:
Arunachalam Dharmalingam, Senior Lecturer, Population Studies, Department of
Sociology and Social Policy, University of Waikato, Hamilton; Ian Pool,
Professor of Demography, Population Studies Centre, University of Waikato,
Hamilton; Sandra Baxendine, Research Fellow, Population Studies Centre,
University of Waikato, Hamilton; Janet Sceats, Managing Director, Portal
Consulting and Associates, Hamilton.
Correspondence: A.
Dharmalingam, Population Studies, Department of Sociology and Social Policy,
University of Waikato, Private Bag 3105, Hamilton. Fax: (07) 838 4654; email:
dharma@waikato.ac.nz
References:
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