Long-term all-cause and cardiovascular mortality following incident myocardial infarction in men and women with and without diabetes: Temporal trends from 1998 to 2009

Background Long-term mortality following myocardial infarction is higher in diabetic than non-diabetic individuals. Early case-fatality after myocardial infarction has improved but it is unclear whether trends extend to long-term mortality. We aimed to determine whether the disparity in long-term all-cause and cardiovascular disease mortality by diabetes status has decreased. Methods All incident myocardial infarction cases were identified from Western Australian whole-population linked data for 1998-2009. Mortality follow-up was available until 30 June 2011. Unadjusted survival was estimated using Kaplan-Meier survival curves. Hazard ratios comparing five-year mortality in diabetic versus non-diabetic people across three periods (1998-2001, 2002-2005, 2006-2009) were estimated from multivariable Cox regression models, and adjusted trends calculated from interaction (diabetes statusxperiod) models. Results There were 22,594 30-day survivors of incident MI. There was little change across the three periods in all-cause mortality in diabetic men (27.1%, 28.2%, 25.5%) and women (34.9%, 36.8%, 36.1%), but small declines from first to last periods in non-diabetic men (14.5% to 12.1%, p=0.03) and women (21.0% to 19.4%, p=0.08). There was no temporal change in the increased all-cause mortality hazard ratios in diabetic versus non-diabetic men and women. Multivariable-adjusted relative risk for cardiovascular disease mortality remained elevated in diabetic women (2006-2009 hazard ratio 1.73, 95% confidence interval 1.29, 2.32) but not in men (2006-2009 hazard ratio 1.08, 95% confidence interval 0.85, 1.37). Conclusions The excess long-term mortality associated with diabetes and excess cardiovascular disease mortality in diabetic women indicates a need for improved secondary prevention in diabetic patients, especially women.