The Japanese Dietary Pattern Is Associated with Longer Disability-Free Survival Time in the General Elderly Population in the Ohsaki Cohort 2006 Study

Abstract

Background: Epidemiologic observations have raised expectations that the Japanese dietary pattern could promote longer disability-free survival (DFS) times among the Japanese population; however, no previous study has examined this issue.

Objective: The aim of this study was to investigate the association between the Japanese dietary pattern and DFS time in the elderly Japanese population.

Methods: We analyzed follow-up data covering a 10-y period for 9456 elderly Japanese individuals (aged ≥65 y) participating in a community-based prospective cohort study. Dietary habits were assessed using a food-frequency questionnaire. Based on previous studies, we used 9 food items to calculate the Japanese Diet Index (JDI) score: rice, miso soup, fish and shellfish, green and yellow vegetables, seaweed, pickled vegetables, green tea (1 point for each item if the consumption value was more than or equal to the median, and 0 points otherwise), beef and pork, and coffee (0 points for each item if the consumption value was more than or equal to the median, and 1 point otherwise). Differences in median age at incident disability or death [50th percentile differences (PDs)] according to quartiles (Q1-Q4) of the JDI score were estimated using Laplace regression.

Results: During the follow-up period, 4233 (44.8%) incident disability or death events occurred. In addition, a higher JDI score was significantly associated with longer DFS time: compared with the lowest quartile of JDI scores (Q1), the multivariate-adjusted 50th PD (95% CI) was 7.1 (1.8, 12.4) mo longer for Q4. Each 1-SD increase of the JDI score was associated with 3.7 (1.7, 5.7) additional months of life without disability (P-trend < 0.01). No differences were seen in sex or chronic condition (no or ≥1 chronic condition) at baseline. A post hoc analysis showed a larger effect on DFS time when using a modified JDI score without coffee.

Conclusion: These results suggest that the Japanese dietary pattern is associated with improved DFS time in the general elderly population.

Keywords: Japanese dietary pattern; Laplace regression; disability-free survival time; elderly people; median age at incident disability or death.