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| Journal of the New Zealand Medical Association,
23-August-2002, Vol 115 No 1160
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Establishing a regional
diabetes register and a description of the registered population after one
year
Kirsten Coppell and Patrick Manning, for the Otago Diabetes
Team
Diabetes service delivery is often less than ideal.
Recognised barriers to adequate diabetes care include: poor collaboration
between general practitioners (GPs) and specialists; variable overall GP care of
people with diabetes; variable overall diabetes management; and an historical
belief amongst some health workers that non-insulin dependent diabetes is a
‘mild illness’ with few long-term
problems.1–4
The Otago Diabetes Team (ODT) was established in 1996 to
look at ways to improve diabetes service delivery in the short term and to
reduce diabetes-related morbidity and mortality in the Otago region. Limited
knowledge about diabetes care amongst GPs and practice nurses was identified as
a key barrier to appropriate diabetes management (unpublished report by ODT,
March 1997). This finding informed a project plan. The key components of the
project were to: establish or update general practice diabetes registers;
develop and implement guidelines for the management of core aspects of diabetes
care;5 organise GP and practice nurse
education; and establish a regional diabetes register in order to monitor
diabetes care and evaluate the project. This paper describes how the Otago
Diabetes Register was established and the enrolled diabetic population after one
year.
MethodsAll GPs in the Otago region
were invited to participate in the ODT project. GPs were informed that the
project involved: establishing or updating general practice diabetes registers;
organising education sessions for GPs and practice nurses; developing and
implementing guidelines for the management of core aspects of diabetes care;
discharging patients from secondary care diabetes clinics who could be
appropriately cared for in primary care and establishing a regional diabetes
register.
A project nurse established or updated general practice diabetes registers. Identifying diagnosed diabetic patients in general practices was facilitated by GPs recalling any of their diabetic patients from memory, and obtaining lists of GP’s patients who had undergone an HbA1c or fructosamine test, or a retinal photograph within the previous 12 months from the community laboratory and retinal screening department, respectively. The number of diagnosed diabetic patients registered with each GP was unknown, but the number of people with diagnosed diabetes in Otago (4800) was estimated using the 1996 census data and a South Auckland prevalence study.6 Identified diabetic patients were sent an invitation from their GP to participate in the project, along with an explanatory pamphlet, a consent form and a stamped addressed envelope for return of the form. Consent was also obtained opportunistically, when patients attended their general practice. The consent form included questions about ethnicity, smoking status and whether eye or feet examinations had been performed in the preceding 12 months. Data collected from general practice medical records included: demographic details; type of diabetes and year of diagnosis; dates and results of retinal and feet examinations; diabetes complications; diabetes medication; and dates and results of biochemistry tests. If data were not readily identified in the medical notes, no extra effort was made to find them, except in the case of those patients who had attended either the Dunedin Hospital outpatient diabetes clinic or eye department. If patients’ diabetes type was uncertain, this was checked with the Dunedin Hospital diabetes clinic. Data were entered into an Access-based programme and Access was used to analyse them. Ethical approval was obtained from the Southern Regional Health Authority Ethics Committee. ResultsAlmost all GPs in Otago accepted the
invitation to participate in the project, but not all were visited in the first
year. During 1998, 90 of 135 (66.7%) GPs were visited, and 1693 consenting
diabetic patients enrolled on the Otago Diabetes Register. There were 867
females (51.2%) and 826 (48.8%) males. Ages ranged from 4 to 97 years and the
median age was 67 years. Figure 1 shows the age distribution of registered
diabetic patients. Two thirds (66.7%) were aged 60 years and over. Most people
were European (91.5%). Few identified as being Maori (2.3%), Pacific (1.2%), or
belonging to ‘Other’ ethnic groups including Chinese, Lebanese and
Indian (1.8%). Fifty five people did not state their ethnicity. About 40% had
never smoked, 44.5% were ex-smokers and 13.5% were current smokers. Smoking
status was unknown for 1.3%. Most people (86.5%) had Type 2 diabetes, 11.9% had
Type 1 diabetes, 1.1% had secondary diabetes and 0.5% had had gestational
diabetes, but not developed Type 2 diabetes.
Overall, about one quarter (26.3%) used diet only to control
their diabetes; one quarter (25.6%) used insulin only; almost one half (44.5%)
took oral hypoglycaemics only; and a few (3.5%) used both insulin and oral
hypoglycaemics. An ACE inhibitor was prescribed for almost one third (32.3%),
and lipid-lowering medication was prescribed for 12.4%.
Figure 1. The proportion of registered diabetic
patients in each 10-year age group
 Table 1 shows that 91% of patients had a blood pressure (BP)
measurement and 90% had an HbA1c result recorded in their medical notes within
12 months prior to the audit date. Almost 70% had a recent weight measurement
recorded. A retinal examination (either photography or fundoscopy by an
ophthalmologist) within two years prior to the audit date was recorded for 65.4%
patients. Height, feet examination and urine albumin:creatinine ratio tests were
performed less frequently: 24.2%, 36.2% and 39.8% respectively.
Table 1. Number and proportion of
patients who underwent process measures within specified time intervals prior to
audit date
*For children and teenagers, the time interval audited
was one year
1159 patients aged over 16 years had their weight recorded
and the range was 34 – 181 kg. Amongst those with Type 2 diabetes, the
mean weights for males (n=490) and females (n=531) were 87.8 kg and 78.7 kg,
respectively. 1543 patients aged over 16 years had a BP measurement recorded.
The mean systolic BP was 140.6 mmHg and the mean diastolic BP was 78.7 mmHg. 41%
had a systolic BP >140 mmHg and 32% had a diastolic BP >80 mmHg. Of the
1522 patients tested, 50.1% had an HbA1c result greater than 7%. The mean HbA1c
for Type 1 and Type 2 patients was 8.8% and 7.2%, respectively. For 853 patients
who had lipid tests, the mean levels for total cholesterol, high density
lipoprotein (HDL) cholesterol and triglycerides were 5.94 mmol/L, 1.23 mmol/L
and 2.17 mmol/L, respectively. Of 675 patients who had a urine
albumin:creatinine ratio test, 40% had a result greater than 3.
DiscussionIt was estimated that about one
third of diagnosed diabetic patients in Otago enrolled on the Register during
1998. While the Register was not complete after one year, this was not
unexpected. Not all GPs were visited during the first year, and the completeness
of general practice diabetes registers was unknown. The method of sending the
consent form with an invitation from the person’s GP, an information
pamphlet about the project and a stamped envelope, facilitated the enrolment
process well, but up to 25% of invited patients did not respond. The reasons for
this were unknown, and the characteristics of these patients were not examined.
Nevertheless, the characteristics of the Otago Diabetes Register population at
the end of one year were similar to other predominantly European diabetes audit
and register populations. The age distribution was similar to a recent
Christchurch audit.7 In that study, the median
age was 65 years, compared with 67 years for the 1998 Otago Register population.
For both these populations, the proportion of people aged over 75 years was 22%.
In Otago, 29% of registered patients were using insulin compared with 27% in
both the Christchurch audit7 and the DARTS
project, Tayside Scotland.8
Type 2 diabetic patients using insulin only were often
misclassified in medical notes as having insulin-dependent diabetes mellitus
(IDDM) or Type 1 diabetes. Efforts were made to correct identified errors, but
some misclassification may persist. This is likely to be small, as the
proportions of registered Otago patients with Type 1 diabetes (11.9%) and Type 2
diabetes (86.5%) were similar to the DARTS project population, in which 11.1%
had Type 1 diabetes and 88.9% had Type 2
diabetes.9
Good diabetes management requires regular monitoring of
parameters such as blood pressure and HbA1c, and retinal screening in order to
reduce the risk, and progression, of
complications.5 These monitoring tests are not
always done. Where the audit interval was the same, the proportions of patients
having these checks in Otago were similar to those in the Christchurch audit
study.7 While there were large differences in
the proportions having feet examinations (Otago 36.2%; Christchurch 66%) and
lipid tests (Otago 50.4%; Christchurch 63%), this is most likely due to the
Christchurch study audit interval for both these parameters being two years, as
opposed to the one-year audit interval in Otago.
HbA1c should ideally be less than
7%.5 In Otago, the same HbA1c assay was used at
both laboratories. For 1998, the mean HbA1c was 7.4%. This was similar to that
of the second pass audit in Christchurch
(7.3%),7 but higher than the 6.9% reported by
PrimeHealth.10
It was unknown whether the PrimeHealth
population was comparable to the Otago registered diabetic population or whether
the HbA1c assay differed.
There is increasing evidence to suggest that good blood
pressure control and good lipid profiles are also important in diabetes
management in order to prevent the onset and progression of macrovascular
complications.11 In 1998, the proportion of
registered patients who had undergone a blood pressure check within the previous
12 months was high (91.4%), and comparable to the Christchurch audit
(92%).7 While the mean diastolic and systolic
blood pressures were good, 32% of patients had a diastolic blood pressure >80
mmHg, and 41% had a systolic >140 mmHg. Because only half of the registered
diabetic patients had lipids tested within the previous year, the mean total
cholesterol level (5.94 mmol/L) may not be representative of the registered
population. Nevertheless, this was comparable to that found in the Christchurch
first pass audit (5.84 mmol/L).7
The method of establishing general practice diabetes
registers and the Otago Diabetes Register in the first year was systematic and
reasonably successful. While the Register was not complete, the enrolled
population after one year appeared to be fairly representative of a
predominantly European diabetic population. Due to this, and checks to ensure
data were as accurate as possible, the results presented probably give a
reasonable description of the diagnosed diabetic population in Otago and the
care received by these patients in 1998. This project and the ongoing
recruitment of patients on to the regional diabetes register will facilitate the
monitoring of changes in diabetes care in Otago, and assist with informing
health service funding decisions and improving diabetes information in New
Zealand.12
Author information:
Members of the Otago Diabetes Team were: Ray Anton, Kirsten Coppell, Ron Craft,
John Gillies, Sherry Lilley, Patricia McKewen, Patrick Manning, Tim Medlicott,
Dean Millar-Coote, Pauline Mumm, Eleanor Murphy, Elizabeth Newsham-West, John
Rutherford and Maree Steele.
Acknowledgements: We
thank all GPs, practice nurses and diabetic patients who participated in the
Otago Diabetes Project. We also acknowledge Ruth Gardener, Gavin Hendry, Robin
Versteeg and Sandra Christie, former members of the Otago Diabetes Team, who
made significant contributions during the early phases of this
project.
Correspondence: Dr
Kirsten Coppell, Department of Preventive and Social Medicine, University of
Otago, P O Box 913, Dunedin. Fax: (03) 479 7164; email: kirsten.coppell@stonebow.otago.co.nz
References:
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