Stress resilience and physical fitness in adolescence and risk of coronary heart disease in middle age

Objective Psychosocial stress is a suggested risk for coronary heart disease (CHD). The relationship of stress resilience in adolescence with subsequent CHD risk is underinvestigated, so our objective was to assess this and investigate the possible mediating role of physical fitness. Methods In this register-based study, 237 980 men born between 1952 and 1956 were followed from 1987 to 2010 using information from Swedish registers. Stress resilience was measured at a compulsory military conscription examination using a semistructured interview with a psychologist. Some 10 581 diagnoses of CHD were identified. Cox regression estimated the association of stress resilience with CHD, with adjustment for established cardiovascular risk factors. Results Low-stress resilience was associated with increased CHD risk. The association remained after adjustment for physical fitness and other potential confounding and mediating factors, with adjusted HRs (and 95% CIs) of 1.17 (1.10 to 1.25), with some evidence of mediation by physical fitness. CHD incidence rates per 1000 person-years (and 95% CIs) for low-stress, medium-stress and high-stress resilience were 2.61 (2.52 to 2.70), 1.97 (1.92 to 2.03) and 1.59 (1.53 to 1.67) respectively. Higher physical fitness was inversely associated with CHD risk; however, this was attenuated by low-stress resilience, shown by interaction testing (p<0.001). Conclusions Low-stress resilience in adolescence was associated with increased risk of CHD in middle age and may diminish the benefit of physical fitness. This represents new evidence of the role of stress resilience in determining risk of CHD and its interrelationship with physical fitness.