Impact of diabetes and previous myocardial infarction on long-term survival: 25-year mortality follow-up of primary screenees of the Multiple Risk Factor Intervention Trial.

Background: The magnitude of coronary mortality risk associated with diabetes or prior myocardial infarction (MI) is debatable. Modulating effects of age, risk factors, and duration of follow-up may explain discrepancies in previous research. Associations with noncardiovascular mortality are little explored.

Objectives: To compare mortality patterns in men with a history of diabetes or MI and to assess modulating effects on mortality of age, cardiovascular risk factors, and follow-up duration.

Methods: We compared the 25-year mortality of 4809 men with diabetes only and 4625 men with MI only (all men aged 35-57 years).

Results: The adjusted hazard ratio (HR) for all-cause mortality for those with MI only vs those with diabetes only was 0.97 (95% confidence interval, 0.92-1.03; P =.32). The pattern of deaths was different: higher coronary mortality (HR = 1.37; P<.001) and lower mortality from noncardiovascular causes (HR = 0.66; P<.001) in those with MI only compared with those with diabetes only. This finding prevailed across all ages and levels of cardiovascular risk factors. Hazard ratios for coronary mortality significantly declined over follow-up (2.7, 1.7, 1.2, 1.1, and 1.0 for < or =5, 6-10, 11-15, 16-20, and >20 years of follow-up, respectively), whereas HRs for noncardiovascular mortality remained relatively constant.

Conclusions: Overall, diabetes and MI were similarly strong predictors of total mortality. Higher mortality from noncardiovascular causes was observed in those with diabetes only, whereas prior MI was more strongly predictive of coronary mortality than diabetes at any age and level of cardiovascular risk factors. The difference in coronary mortality between the 2 groups was most evident in the first 10 years of follow-up.