Association of frailty screening–based preventive care with long-term care certification rates among Japanese people aged 75 years and older: an interrupted time-series analysis

BACKGROUND: In rapidly ageing societies, promoting healthy ageing is essential. Japan launched a nationwide policy using questionnaire-based frailty screening to help older adults recognise their risk and engage in preventive care. This study evaluated whether this policy was associated with changes in long-term care (LTC) need. METHODS: The intervention was a health guidance programme initiated through frailty screening and delivered at the municipal level from April 2022. We conducted this single-city study in Sukagawa City, Japan. We extracted monthly data on LTC certifications and population from January 2015 to December 2025. We analysed these data using an interrupted time-series design with segmented regression. The outcome was the monthly age-standardised LTC certification rate among adults aged ≥75 years. We assumed a slope change occurring 12 months after the intervention and fitted Poisson regression models with a log link and an offset for population. RESULTS: Following the intervention, the trend in the LTC certification rate among adults aged ≥75 years declined relative to the pre-intervention trend (annualised RR for the change in trend, 0.974; 95% CI, 0.963-0.983). At the end of follow-up, the model-estimated age-standardised LTC certification rate was 6.8% lower than the counterfactual rate projected from continuation of the pre-intervention trend (95% CI, 4.4%-10.0%). CONCLUSION: The frailty screening-based preventive care initiative for older adults was associated with a reduction in LTC certification rates. These findings suggest the potential value of linking frailty screening with broad preventive guidance as a municipal approach to addressing population-level LTC need.