Sex differences in survival after myocardial infarction in Sweden, 1987-2010

Abstract

Objective In this nationwide study, we investigated age-specific and sex-specific trends in sex differences in survival after acute myocardial infarction (AMI), including deaths from coronary heart disease (CHD) that occurred outside hospital. Methods Observational study in Sweden of 28-day and 1-year mortality among 658 110 persons (35.7% women) aged 35-84 years with a first-time CHD event 1987-2010 with data retrieved from the national Swedish death and hospital registries. Results Age-adjusted 28-day case fatality decreased from 23.5% to 8.5% over the period (p<0.05). In hospitalised cases, short-term survival in women aged 35-54 years compared with men of the same age was poorer, not changing appreciably over time (HRs for women relative to men 1.63 (95% CI 1.28 to 2.08) at age 35-54 years and 1.28 (95% CI 1.12 to 1.46) at age 55-64 years in 2005-2010), but after adjustment for comorbidities, differences between men and women were no longer significant (HR 1.25 (95% CI 0.97 to 1.61) and 1.05 (95% CI 0.91 to 1.20)). When CHD deaths outside hospital were included, women had better prognosis regardless of age and period. In patients surviving the first 28 days, age-adjusted 1-year case fatality decreased from 15.3% to 7.7% (p<0.05) for both men and women. After adjustment for comorbidities, no significant sex differences persisted below the age of 75 years in the last period. Female 28day survivors 75-84 years old had a consistently better prognosis than older men. Conclusions The worse short-term outcomes in women <55 years of age hospitalised with AMI did not persist after adjustment for comorbidities. When CHD deaths outside hospital were included, women had consistently better short-term prognosis. In 28-day survivors, women did not fare worse than men when differences in comorbidities were considered.