[Relationship between participation in a secondary screening test for the frail elderly and new onset of the need for long-term care among the elderly in a rural town].

OBJECTIVES: The present cohort study investigated the relationship between participation in a secondary screening test for the frail elderly and the findings of this screening test, and the relationship between participation and new onset of the need for long-term care in the elderly. METHODS: A primary screening survey was conducted on all 4,050 functionally independent elderly people aged > or = 65 years living in Ishikawa Town, Japan. We included 3,150 subjects for analysis, dividing them into the following 3 groups: 1) non-frail elderly, 2) possible frail elderly who participated in the secondary screening test, and 3) possible frail elderly who did not participate in the secondary screening test. We used Cox's proportional hazards model to calculate the hazard ratios of new onset of the need for long-term care by the participating and non-participating groups as compared to the non-frail group over 2 years. RESULTS: The proportion of non-frail elderly and possible frail elderly was 72.7% (n=2,289) and 27.3% (n=861), respectively. The number of subjects who did not participate in the secondary screening test (n=582) were 2.1-fold greater than that of subjects who did (n=279). The prevalences of withdrawal and impaired instrumental activity of daily living were significantly higher in the non-participating group than in the participating group. During the 2-year follow-up period, 168 subjects developed the need for long-term care. The incidence of new onset of the need for long-term care for each group (/1,000 persons) was 24.0 in the non-frail group, 93.2 in the participating group, and 149.5 in the non-participating group. The hazard ratios of new onset of the need for long-term care were 2.55 (95% confidence interval, 1.59-4.10) for the participating group and 4.46 (3.15-6.32) for the non-participating group after adjustment for confounding factors, including sex, age, and type of household. The hazard ratios were 0.75 (0.41-1.37) for the participating group and 1.09 (0.65-1.82) for the non-participating group after additional adjustment for total points on the Kihon Checklist (a frailty checklist) for assessing the frail elderly. CONCLUSION: Compared to non-frail elderly, the possible frail elderly had an increased risk of developing the need for long-term care. Moreover, compared to the possible frail elderly who participated in the secondary screening test, the possible frail elderly who did not participate in the test had a further increased risk of developing the need for long-term care.