A Retrospective Chart Review of Uninsured Encounters in a Primary Care Hospital in Japan.

Introduction Lack of health insurance is known to delay care-seeking and contribute to preventable morbidity. Although Japan has established a universal health insurance system, more than 10% of households have unpaid insurance premiums, and approximately 2.5% possess insurance certificates with restricted or no validity. Under these circumstances, preventable deaths attributable to delayed medical care for financial reasons have been reported. Individuals facing unstable employment or job loss are particularly vulnerable to premium non-payment, even when willingness to pay exists. The actual scale, characteristics, and clinical outcomes of uninsured patients in Japan remain largely unknown. Materials and methods We conducted a retrospective chart review at a small suburban hospital in Japan. The characteristics of patients without any form of health insurance at the time of the encounter were extracted from medical records from October 2021 to September 2025. Patient consent was obtained on an opt-out basis. Results Over the four-year study period, 20 patients received medical care at the hospital without any form of health insurance. Twelve patients (60%) required hospital admission at their first encounter. Nine patients (45%) were diagnosed with psychological disorders. Severe functional impairment or death occurred in 10 patients (50%), including two cases of death. Prior to hospital presentation, four patients (20%) had attempted to apply for public assistance at a municipal office but were denied. Conclusions Some individuals who remained outside the national insurance system present with severe and preventable illnesses. Although this study cannot establish a causal relationship, lack of insurance coverage may contribute to delayed care and adverse health outcomes. Efforts to remove administrative barriers and strengthen social work support may help reduce preventable harm and promote health equity within Japan's healthcare system.