The improvement effect of working through the Silver Human Resources Center on pre-frailty among older people: a two-year follow-up study

BACKGROUND: Although the health benefits of working in old age are well known, no research has examined them among older people with pre-frailty. We examined the improvement effect of working through the Silver Human Resources Center (SHRC) on pre-frailty among older people in Japan. METHODS: We carried out a two-year longitudinal survey from 2017 to 2019. Among 5,199 older people, the analysis included 531 participants who were judged to be of pre-frailty status at baseline and who completed both surveys. We utilized the records of participants’ work through the SHRC from 2017 to 2019. The evaluation of the frequency of working through the SHRC was categorized as “less-working” (i.e., less than a few times a month), “moderate-working” (i.e., one to two times a week), and “frequent-working” (i.e., more than three times a week). The transition of frailty status was classified as “improved” (from pre-frailty to robust) and “non-improved” (from pre-frailty to pre-frailty or frailty). Logistic regression was used to assess the influence of the frequency of working through the SHRC on the improvement of pre-frailty. The analysis model was adjusted for age, sex, working for financial reward, years of membership, community activities, and health status at baseline. Inverse-probability weighting was used to correct for survival bias in the follow-up period. RESULTS: The improvement rate of pre-frailty during follow-up was 28.9% among the less-working, 40.2% in the moderate-working, and 36.9% in the frequent-working groups. The improvement rate in the less-working group was significantly lower than that in the other two groups (φ = -2.4). Multivariable logistic regression analysis showed that individuals in the moderate-working group had significantly higher odds of pre-frailty improvement than those in the less-working group (OR: 1.47, 95% CI: 1.14–1.90), and no significant differences were found between the frequent-working and less-working groups. CONCLUSIONS: We found that the participants engaged in moderate working through the SHRC significantly increased their rate of pre-frailty improvement, while frequent working showed no significant association. Therefore, in the future it is important to provide moderate work to older people with pre-frailty according to their health status. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12877-023-03978-z.