Improving 30-day case fatality after incident myocardial infarction in people with diabetes between 1998 and 2010

OBJECTIVE: To compare population-level trends in 30-day case fatality following incident myocardial infarction (MI) in people with diabetes and those without diabetes. METHODS: We identified all hospitalised incident MIs in 35-84 year olds from the Western Australian Data Linkage System for 1998-2010, stratified by diabetes status. Crude and age- and sex-standardised 30-day case fatality were estimated, and age- and sex-adjusted trends were calculated from logistic regression. We calculated the trend in risk of 30-day death associated with diabetes from multivariable logistic regression, adjusting for demographics, comorbidities and MI type. RESULTS: 26 610 hospitalised incident MI cases were identified, 24.8% of whom had diabetes. The prevalence of heart failure fell in people with diabetes, concurrent with increasing chronic kidney disease and prior coronary heart disease and increasing levels of evidence-based therapies. Case fatality in people with diabetes fell from 11.65%, in 1998-2001, to 3.96% by 2008-2010. Age- and sex-standardised case fatality declined at a greater rate in those with diabetes (-10.6%/year, 95% CI -12.8% to -8.2%) compared to non-diabetics (-6.9%/year, 95% CI -8.3% to -5.3%; interaction p=0.005). The adjusted risk of 30-day death after incident MI was 1.23 times higher in diabetics than non-diabetics in 1998-2001 (95% CI 1.01 to 1.50), but was lower by 2008-2010 (OR 0.64, 95% CI 0.46 to 0.88). CONCLUSIONS: Greater improvements in 30-day case fatality following incident MI in people with diabetes during the 13-year study period has led to diabetes no longer being an independent predictor of early death following incident MI by 2008-2010.