Association between psychological distress and disability-free life expectancy in the older Japanese adults.

Background: Our study aimed to investigate the association between psychological distress and disability-free life expectancy (DFLE).

Methods: In 2006, a cohort study was conducted of 12,365 Japanese individuals aged ≥65 years, who were followed-up for 13 years. Psychological distress was measured using the Kessler 6-item psychological distress scale and was categorized into no (0-4), mild (5-9), moderate (10-12), and serious distress (13-24). The number of participants was 1277 (22.4 %) for mild distress, 330 (5.8 %) for moderate, and 208 (3.6 %) for serious in men, and was 1635 (24.6 %), 467 (7.0 %), and 384 (5.8 %) in women. Sex-specific DFLE was defined as the mean years a person could expect to live without disability and calculated by Interpolated Markov Chain (IMaCh) software.

Results: Compared to no distress, DFLE loss per person was 1.21, 2.61, and 4.43 years for mild, moderate, and serious distress respectively in men. At population level, DFEL loss (i.e., DFLE loss per person×number of participants) was 1545.17, 861.30, and 921.44 years for mild, moderate, and serious distress respectively in men. Accordingly, 46.4 % of the total DFLE loss was attributable to mild distress, 25.9 % to moderate, and 27.7 % to serious in men. Similarly, the results were 42.2 %, 25.4 %, and 32.4 % in women.

Limitations: Psychological distress was measured only once at baseline, and 2409 participants were excluded from the analysis because of missing data on exposure.

Conclusions: At population level, almost half of the total DFLE loss could be attributable to mild distress, underscoring the importance of population strategy for all levels of distress in promoting healthy aging.