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

Abstract

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. 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. 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.