Comparative Trends in the Incidence of Hospitalized Myocardial Infarction and Coronary Heart Disease in Adults With and Without Diabetes Mellitus in Western Australia From 1998 to 2010

BACKGROUND: The risk of myocardial infarction (MI) is elevated in people with diabetes mellitus (DM) compared with non-DM counterparts. The aim of this study was to compare population trends in the incidence of hospitalized MI and coronary heart disease (CHD) in adults with and without DM. METHODS AND RESULTS: All incident hospitalized MI and CHD events were identified from whole-population hospital data in Western Australia for 1998 to 2010. Annual age-standardized MI and CHD incidence rates were calculated for people with and without DM aged 35 to 84 years and age-adjusted trends estimated from Poisson regression. There were 26 610 incident MI and 56 142 incident CHD cases during the study period. MI incidence rates fell in men (-2.9%/y; 95% confidence interval [CI], -3.7 to -2.1) and women (-3.8%/y; 95% CI, -4.8 to -2.1) with DM, representing overall reductions of 35% and 43% respectively, with comparable reductions in incident CHD. Downward trends in MI incidence in those with DM were most apparent in 55- to 84-year olds. In adults without DM, there was no decline in MI incidence but a small significant decrease in incident CHD (men, -1.5%/y; 95% CI, -1.8 to -1.2 and women, -1.3%/y; 95% CI, -1.8 to -0.9). Incidence rate ratios for MI in men with versus without DM declined from 4.5 (95% CI, 4.2-4.8) to 3.1 (95% CI, 2.9-3.3) and from 6.0 (95% CI, 5.4-6.6) to 3.8 (95% CI, 3.5-4.1) in women between 1998 and 2010. CONCLUSIONS: There have been significant reductions in incidence rates of MI and CHD in adults with DM between 1998 and 2010; however, the excess risk of MI incidence remains 3 to 4× greater in people with DM.