Type A behaviour and risk of coronary heart disease: The JPHC Study

BACKGROUND: Although numerous studies of type A behaviour and risk of coronary heart disease (CHD) have been reported in the west (with mixed findings), few studies have been carried out in Asian populations. METHODS: We examined prospectively the association between type A-behaviour and risk of CHD incidence within a cohort of 86 361 Japanese men and women aged 40-69 years. A total of 669 cases of newly diagnosed CHD occurred between the baseline questionnaire (1990-94) and the end of follow-up in January 2004. RESULTS: We found no overall evidence of an association between type A and CHD incidence. The multivariate hazard ratio (HR) and 95% confidence intervals for CHD incidence in the highest vs lowest level of type A was 1.19 (0.94-1.51) overall. Contrary to expectation, Japanese men with lower levels of type A behaviour (lower levels of impatience, aggressiveness and competitiveness) appeared to be at significantly increased risk of CHD incidence (HR = 1.32; 95% CI 1.02-1.72). In contrast to men, there was insignificant but a tendency for reduced risk of CHD incidence (HR = 0.79, 95% CI 0.46-1.34) for women with lower levels of type A behaviour. CONCLUSIONS: Type A behaviour does not predict CHD incidence in the Japanese population. Among males, type B behavioural patterns appear to confer increased CHD risk. Our findings suggest that the cardio-toxic effect of type A behaviour is gender-specific and culturally contingent.