The impacts of health examinations and smoking on disease mortality risk in Japan: a longitudinal cohort of 720,611 Japanese life insured persons.

OBJECTIVES

To evaluate the impacts of health examinations (HE) and smoking on disease mortality risk in Japan.

METHODS

By using the large cohort database of a Japanese life insurance company, 720,611 subjects aged 20 to 80 years, who had contracted for life insurance between April 1, 1995 and March 31, 1998, were followed up until September 30, 1999. Cox's proportional hazard model was used to estimate age-adjusted relative risk (RR) for disease death.

RESULTS

After adjusting for age, disease mortality in smokers was significantly higher than that in non-smokers (men, RR 1.51, 95% CI: 1.25-1.81; women, RR 1.54, 95% CI: 1.12-2.11). Meanwhile, disease mortality in HEees (those who had got HE within the past 2 years) was significantly lower than that in non-HEees (men, RR 0.70, 95% CI: 0.56-0.88; women, RR 0.71, 95% CI: 0.54-0.92). The magnitude of the impact of HE on disease mortality risk varied according to smoking status. Non-smokers showed a significantly lower risk associated with HE, whereas smokers did not.

CONCLUSIONS

HE may allow an appreciable reduction in disease mortality, however, the reduction effect may be limited to non-smokers. Smoking cessation may be essential to improve the preventive effects of HE.