Association Between Duration of Usual Source of Care and Patient-reported Primary Care Quality in Japan: A Nationwide Cross-sectional Study

Among Japanese adults with a USC, longer continuity correlates with better PX. "Years of attendance" works as a practical quality indicator, with interpersonal continuity mattering more than institutional continuity. These findings do not extend to adults without a USC and should be interpreted within this population. Future longitudinal studies are required to inform policies aimed at sustaining continuity.