Diverging trends for onset of acute myocardial infarction, heart failure, stroke and mortality in young males: role of changes in obesity and fitness

Background As opposed to the decreasing overall rates of coronary heart disease (CHD) incidence and overall cardiovascular disease (CVD) mortality, heart failure (HF) and stroke incidence are increasing in young people, potentially due to rising rates of obesity and reduced cardiorespiratory fitness (CRF). Objectives We investigated trends in early major CVD outcomes in a large cohort of young men. Methods Successive cohorts of Swedish military conscripts from 1971 to 1995 (N = 1,258,432; mean age, 18.3 years) were followed, using data from the National Inpatient and Cause of Death registries. Cox proportional hazard models were used to analyse changes in 21-year CVD event rates. Results 21-year CVD and all-cause mortality and incidence of acute myocardial infarction (AMI) decreased progressively. Compared with the cohort conscripted in 1971-1975 (reference), the hazard ratios (HRs) for the last 1991-1995 cohort were 0.50 [95% confidence interval (CI) 0.42-0.59] for CVD mortality; 0.57 (95% CI 0.54-0.60) for all-cause mortality; and 0.63 (95% CI 0.53-0.75) for AMI. In contrast, the incidence of ischaemic stroke, intracerebral haemorrhage and HF increased with HRs of 1.43 (95% CI 1.17-1.75), 1.30 (95% CI 1.01-1.68) and 1.84 (95% CI 1.47-2.30), respectively. During the period, rates of obesity increased from 1.04% to 2.61%, whilst CRF scores decreased slightly. Adjustment for these factors influenced these secular trends only moderately. Conclusion Secular trends of young-onset CVD events demonstrated a marked shift from AMI and CVD mortality to HF and stroke incidence. Trends were significantly, though moderately, influenced by changing baseline BMI and CRF.