Supplementary Material

No data


Background: Social relationships might be a key factor for preventing the decline of instrumental activities of daily living (IADL). In the current study, we examined the association between social relationships and IADL decline, and how this association differed by age.

Methods: The study employed a prospective cohort design by introducing complete sampling. Questionnaires were distributed in 2011 and 2017 to all residents over 65 years old living in a suburban area of central Japan. Analysis included 501 residents who were independent in IADL in 2011 and who participated after 6 years without missing data. Social relationships were evaluated by the Index of Social Interaction, and IADL were measured by the Tokyo Metropolitan Institute of Gerontology Index of Competence. Multiple logistic regression analysis was used to examine the association between social relationships and IADL. An age-stratified analysis was also conducted.

Results: One hundred three participants showed IADL decline after 6 years. Age (OR = 1.18) and social relationships (OR = 0.79) were significantly associated with IADL decline. In the age-stratified analysis, age (OR = 1.21) and having a musculoskeletal disease (OR = 5.09) were significantly associated with IADL decline among individuals 65–74 years old. Among individuals 75 years old or older, age (OR = 1.31) and social relationships (OR = 0.58) were significantly associated with IADL decline.

Conclusion: Social relationships might prevent IADL decline in older people. Furthermore, their effects might differ by age group. Promoting social relationships considering ageis important for prevention of IADL decline.