Impact of diabetes and gender on survival after acute myocardial infarction in the Province of Quebec, Canada—a population‐based study

AIMS: To examine the impact of diabetes, gender and their interaction on 30-day, 1-year and 5-year post-acute myocardial infarction (AMI) mortality in three age groups (20-64, 65-74 and > or = 75 years). METHODS: Retrospective analysis including 23 700 patients aged > or = 20 years (22% with diabetes) admitted to hospital for a first AMI in any hospital in the Province of Quebec, Canada, between April 1995 and March 1997. Administrative databases were used to identify patients and assess outcomes. RESULTS: Regarding 30-day mortality, there was non-significant interaction between diabetes and gender. Women aged < 75 years had, independently of diabetes status, at least a 38% (P < 0.05) higher mortality than their male counterparts after adjustment for socio-economic status and co-morbid conditions. Gender difference disappeared, however, after controlling for in-hospital complications. Regarding 1-year mortality (31-365 days), there was no significant gender disparity for all age groups. During the 5-year follow-up, no gender differences were seen in any age group, except for younger (< 65 years) women with diabetes, who had a 52% (P = 0.004) higher mortality than men after controlling for co-variables. This female disadvantage was demonstrated by a significant interaction between diabetes and gender in patients aged < 65 years (P = 0.009). CONCLUSIONS: The higher 30-day mortality post-AMI in younger (20-64 years) and middle-aged (65-74 years) women compared with men was not influenced by diabetes status. However, during the 5-year follow-up, the similar gender mortality observed in patients without diabetes seemed to disappear in younger patients with diabetes, which may be explained by the deleterious, long-term, post-AMI impact of diabetes in younger women.