Prospective study of oral symptoms and mortality in Japan

Objectives: Previous studies suggest that the state of the oral cavity might be linked to systemic diseases. This study evaluated the effects of oral symptoms on mortality from coronary heart disease (CHD), cerebrovascular disease (CVD) and pneumonia. Methods: The data used were derived from a cohort study on the relationship between lifestyles and health in Southwestern Japan. Of cohort members, 4264 subjects aged 50-79 years were included in the present analysis. The baseline survey was conducted from 1987-1989 using a questionnaire including the following items related to oral symptoms: ‘sensitive teeth', ‘difficulty in chewing', ‘bleeding gums', and ‘mouth feels sticky', smoking habit, alcohol consumption, level of exercise, weight and height. Follow-up data obtained until the end of 2003 (1999 in one of the three areas examined) was used in the present analysis. Cox proportional hazard model was employed to estimate the relative risks (RRs) and 95% confidence intervals (CIs) for mortality from CHD, CVD and pneumonia by sex, while adjusting for age, smoking habit, alcohol consumption, level of exercise and body mass index. Results: The numbers of deaths during the follow-up period were 67, 131 and 118 for CHD, CVD and pneumonia, respectively. Subjects complaining that their ‘mouth feels sticky' compared to those without this symptom had a higher risk of pneumonia in both sexes [RR: 2.1 (95%CI: 1.2-3.8) in men and 1.7 (95%CI: 0.8-3.5) in women]. An increased risk of pneumonia was also observed among subjects complaining of ‘difficulty in chewing' in men (RR=1.9; 95%CI: 1.2-3.0). For men aged 50-59 years, subjects complaining of ‘difficulty in chewing' or ‘bleeding gums' had a higher risk of CVD. Conclusions: The present results indicate that some oral symptoms are independent predictors of mortality, especially from pneumonia. However, caution must be taken in interpreting the causal relationship between oral disease and mortality.