An association between ethnicity and cardiovascular outcomes for people with Type 2 diabetes in New Zealand

To investigate the association between ethnicity and risk of first cardiovascular (CV) event for people with Type 2 diabetes in New Zealand.

A prospective cohort study using routinely collected data from a national primary health care diabetes annual review programme linked to national hospital admission and mortality data. Ethnicity was recorded as European, Maori, Pacific, Indo-Asian, East-Asian or Other. A Cox proportional hazards model was used to investigate factors associated with first CV event. Data was collected from 48,444 patients with Type 2 diabetes, with first data collected between 1 January 2000 and 20 December 2005, no previous cardiovascular event at entry and with complete measurements. Risk factors included ethnicity, gender, socio-economic status, body mass index, smoking, age at diagnosis, duration of diabetes, systolic blood pressure, serum lipids, glycated haemoglobin and urine albumin : creatinine ratio. The main outcome measures were time to first fatal or non-fatal CV event.

Median follow-up was 2.4 years. Using combined European and Other ethnicities as a reference, hazard ratios for first CV event were 1.30 for Maori (95% confidence interval 1.19-1.41), 1.04 for Pacific (0.95-1.13), 1.06 for Indo-Asian (0.91-1.24) and 0.73 for East-Asian (0.62-0.85) after controlling for all other risk factors.

Ethnicity was independently associated with time to first CV event in people with Type 2 diabetes. Maori were at 30% higher risk of first CV event and East-Asian 27% lower risk compared with European/Other, with no significant difference in risk for Pacific and Indo-Asian peoples.