Objective: To examine the association between positive psychological factors and the risk of pneumonia-associated mortality in a large prospective Japanese cohort.
Methods: The Japan Collaborative Cohort Study assessed 64,231 participants (26,293 men and 37,938 women), aged 40-79 years, without a history of stroke, myocardial infarction, cancer or tubercules at baseline (1988-1990). We used self-administered questionnaires about lifestyle, medical history, and mental states, including three positive psychological factors, and followed-up for mortality outcomes until the end of 2009. The Cox proportional hazard model was used to calculate the multivariable hazard ratios (HRs) with 95% confidence intervals (CIs) of pneumonia-associated mortality after adjustment for potential confounding factors, mutually positive psychological factors, and consideration for the competing risk.
Results: Having Ikigai (in Japanese) was inversely associated with the risk of pneumonia-associated mortality in both men and women; the multivariable HRs (95% CIs) for high versus low levels were 0.68 (0.48-0.97), P trend =0.090 and 0.66 (0.43-1.00), P trend =0.146, respectively. Such inverse associations were more pronounced in working men and non-working women; the multivariable HRs (95% CIs) for high versus low levels were 0.52 (0.32-0.85), P trend =0.010 and 0.59 (0.37-0.94), P trend =0.079, respectively. Being relied upon by others and Enjoyment of life was not associated with the risk in both genders.
Conclusion: Having Ikigai was associated with a lower risk of pneumonia-associated mortality in both genders, especially in working men and non-working women.
Keywords: Cohort study; Employment status; Mortality; Pneumonia; Positive psychological factor.
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