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Audit of diabetes testing within selected general practices and estimates of type II diabetes among the Pacific population in Christchurch

Student: Cindy (Yu-Hsing) Chang
Supervisors: Dr Pauline Barnett, Dr Alistair Humphrey, Ms Maggie Wilson.
Sponsor: Christchurch School of Medicine and Health Sciences

This study aims to estimate the prevalence of known Type II diabetes in the different ethnic and age groups, among patients enrolled in selected general practices in Christchurch. It also aims to evaluate how well diabetes is screened for within these selected general practices. Previous studies have stated it is essential to detect people with diabetes in order for these patients to be treated and therefore avoid the health complications.

Six general practices from Christchurch with high proportions of Pacific patients enrolled are selected since the Pacific population is the main focus in this study. I used Med Tech 32 Query Builder to generate both a list of patients aged 25 or over, with diabetes status, and a list of patients who have had a glucose test in the last three years. The clinical records of these patients are searched through in order to find any records of fasting blood glucose (FBG) or HbA1c test done since 1 January 2002. FBG test is one of the current diagnostic criteria for diabetes. However, some practices have adopted HbA1c test as their method of screening, even though no international body currently recommends this screening method. In this study, all the patients aged 25 or over who have had a FBG or HbA1c test in the past three years are considered to be screened.

Focusing on three ethnic groups, there are 651 Pacific, 5056 Europeans, and 598 Maori patients included in this study. In the Census 2001, there were 7617 people who classified themselves as Pacific Islanders in Christchurch.

It is observed that the prevalence of Type II diabetes and screening of the Pacific population has a similar pattern to those of the Maori population. The prevalence of diabetes peaks in the age group of 55 to 64 years in both populations, while the prevalence peaks in the age group of 75 to 84 years in the European population. There are more European diabetes in the older age groups than those of Maori and Pacific. A possible reason is the adequate screening of diabetes within the European population. Early diagnoses lead to a better control over the disease, and therefore longer survival.

Another important observation is the high proportion of Type II diabetes in the patients who have been screened for in Pacific and Maori populations, assuming that those diagnosed with Type II diabetes received the diagnoses via screening. The screening rate of Europeans is similar to those of Maori and Pacific patients; but the prevalence of diagnosed diabetes among screened patients is significantly higher in the latter groups, therefore the need for screening is not met in Maori and Pacific population. For example, in the age group of 35 to 44 years, 34% of Pacific patients and 15% of Maori who were screened were diagnosed with diabetes, compared with, only 7% of screened Europeans, despite similar screening rates for all groups (28% Pacific, 23% Maori and 25% European). This clearly indicates a need for screening of all Maori and Pacific patients at least aged 35 or more in these 6 general practices. Previous studies have recommended screening non-Europeans age 40 years or more.

In conclusion, due to higher prevalence of diabetes in Pacific and Maori population, people of these ethnic groups may not be efficiently screened if the screening rate is not significantly higher than those of Europeans. In addition, these people should also be screened from a younger age than Europeans.