Improved but still high short- and long-term mortality rates after myocardial infarction in patients with diabetes mellitus: a time-trend report from the Swedish Register of Information and Knowledge about Swedish Heart Intensive Care Admission

Abstract

Objective: The aim of the study was to compare time-trends in mortality rates and treatment patterns between patients with and without diabetes based on the Swedish register of coronary care (Register of Information and Knowledge about Swedish Heart Intensive Care Admission [RIKS-HIA]). Methods: Post myocardial infarction mortality rate is high in diabetic patients, who seem to receive less evidence-based treatment. Mortality rates and treatment in 1995–1998 and 1999–2002 were studied in 70 882 patients (age <80 years), 14 873 of whom had diabetes (the first registry recorded acute myocardial infarction), following adjustments for differences in clinical and other parameters. Results: One-year mortality rates decreased from 1995 to 2002 from 16.6% to 12.1% in patients without diabetes and from 29.7% to 19.7%, respectively, in those with diabetes. Patients with diabetes had an adjusted relative 1-year mortality risk of 1.44 (95% CI 1.36 to 1.52) in 1995–1998 and 1.31 (95% CI 1.24 to 1.38) in 1999–2002. Despite improved pre-admission and in-hospital treatment, diabetic patients were less often offered acute reperfusion therapy (adjusted OR 0.85, 95% CI 0.80 to 0.90), acute revascularisation (adjusted OR 0.78, 95% CI 0.69 to 0.87) or revascularisation within 14 days (OR 0.80, 95% CI 0.75 to 0.85), aspirin (OR 0.90, 95% CI 0.84 to 0.98) and lipid-lowering treatment at discharge (OR 0.81, 95% CI 0.77 to 0.86). Conclusion: Despite a clear improvement in the treatment and myocardial infarction survival rate in patients with diabetes, mortality rate remains higher than in patients without diabetes. Part of the excess mortality may be explained by co-morbidities and diabetes itself, but a lack of application of evidence-based treatment also contributes, underlining the importance of the improved management of diabetic patients.