Factors Contributing to Health Deterioration in the Japanese Long-Term Care Insurance System in Terms of Instrumental Activities of Daily Living

This study aimed to determine which instrumental activities of daily living (IADL) are associated with health deterioration from the “support level” to the “care level” among users of the long-term care insurance system in Japan. From April 2017 to March 2020, we conducted a retrospective follow-up survey on 178 Japanese community-dwelling older adults (64 men, 114 women) newly certified as support level. Independent variable was 8 IADL items and the outcome defined as the “support level maintenance time.” Cox models were used to assess the risk of health deterioration, with adjustments for age group, family composition, dementia status, and frailty status by gender. Dependence on 5 items, “laundry” (hazard ratio [HR] =2.5; 95% confidence interval [CI]: 1.1-5.8), “cooking” (HR = 3.7; 95% CI: 1.1-12.2), “telephone use” (HR = 2.4; 95% CI: 1.2-4.7), “financial management” (HR = 2.5; 95% CI: 1.2-5.0), and “medication management” (HR = 2.4; 95% CI: 1.2-4.8), was independently associated with a worse outcome among men, whereas dependence on “financial management” (HR = 2.6; 95% CI: 1.5-4.7) and “medication management” (HR = 2.0; 95% CI: 1.1-3.5) was independently associated with a worse outcome among women. These findings suggest that difficulties in “financial management” and “medication management” are common factors associated with health deterioration from the support to the care level among both genders. An association with household tasks was also seen among men, indicating that a paradigm shift is needed to increase the participation of men in household tasks.