[Investigating the relationship between higher life functions, overall mortality, and incidence of care needs in long-term follow-up study of the local population: The Kamogawa Cohort Study].

Objectives　In addition to physical independence such as ADLs, higher-level functional capacity ("instrumental self-maintenance," "intellectual activity," and "social role") are necessary to lead the final stage of life as independently and for as long as possible. Accordingly, in a long-term follow-up study of the local population, we examined the association of health status (total mortality and incidence of care needs) with instrumental independence, intellectual activity, and social role.Methods　We used participant data from the Kamogawa cohort study, which included surveyed use of health service, health status, disease prevalence, and use of long-term care insurance service for Kamogawa citizens in Chiba prefecture from 2003 to 2013. We compared the differences in lifestyle and higher-level functional capacity, by status of death and using the Long-term Care Insurance service. Higher-level functional capacity was assessed with the Tokyo Metropolitan Institute of Gerontology-Index of Competence (TMIG-IC); answer to each question, each domain score, and total score were examined.Results　During the follow-up period to the end of March 2013, 810 deaths and 917 care needs were observed among the 6,503 people who consented to be followed up. The adjusted HR of higher-level functional capacity for all-cause mortality was "instrumental self-maintenance," score 4 or 5 to less than 3: 2.03 (95%CI: 1.59-2.60), "intellectual activity," score 4 to less than 3: 1.39 (95%CI: 1.09-1.77), and "social role," score 4 to less than 3: 1.28 (95%CI: 1.03-1.59). In subgroup analyses by sex, "instrumental self-maintenance" was associated with both men and women, but "intellectual activity" and "social roles" were associated with women only. The adjusted HRs for the incidence of care needs were 1.93 (95%CI: 1.55-2.40) for "instrumental self-maintenance" and 1.30 (95%CI: 1.07-1.58) for "social role." In subgroup analyses by sex, "instrumental self-maintenance" was associated with both genders, but "social role" was observed only for women.Conclusion　Higher-level functional capacity ("instrumental self-maintenance," "intellectual activity," and "social role") was significantly associated with total mortality and incidence of care needs.