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 28-day 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.

Keywords: acute coronary syndromes; cardiac risk factors and prevention; coronary artery disease; epidemiology.

Figure 1

Twenty-eight-day age-adjusted case fatality (%) and HRs for women compared with men after hospital admission for acute myocardial infarction in Sweden 1987–2010. Age adjusted and multiadjusted for age, diabetes, hypertension, stroke, heart failure, atrial fibrillation, chronic respiratory disease, percutaneous coronary intervention, renal insufficiency and malignancy. For every HR, the group of men are set as a reference in each period and age group.

Figure 2

Twenty-eight-day age-adjusted case fatality (%) and HRs for women compared with men for all first acute coronary events (hospital admission for acute myocardial infarction or acute coronary death outside hospital) in Sweden from 1987 to 2010. Age adjusted and multiadjusted for age, diabetes, hypertension, stroke, heart failure, atrial fibrillation, chronic respiratory disease, percutaneous coronary intervention, renal insufficiency and malignancy. For every HR, the group of men are set as a reference in each period and age group.

Figure 3

Age-adjusted case fatality (%) and HRs after acute myocardial infarction for adults aged 35–84 years from days 29 to 365 in Sweden from 1987 to 2011. Age adjusted and multiadjusted for age, diabetes, hypertension, stroke, heart failure, atrial fibrillation, chronic respiratory disease, percutaneous coronary intervention, renal insufficiency and malignancy. For every HR, the group of men are set as a reference in each period and age group.