Health Indifference and the Inverse Association Between Symptom Burden and Healthcare Use: A Longitudinal Cohort Study from the Japan Society and New Tobacco/Infodemic Survey

Background Approximately 30% of adults delay or avoid healthcare despite experiencing symptoms, leading to preventable morbidities and substantial economic losses. Understanding the psychological mechanisms, particularly health indifference, that drive this paradox is critical for developing effective interventions to address this issue. Methods This longitudinal cohort study analyzed data from the Japan Society and New Tobacco/Infodemic Survey, a nationwide online panel survey conducted annually from February 2021 to February 2023. Among the 26,000 baseline participants from all 47 Japanese prefectures, 15,519 adults completed all three survey waves. Health indifference was measured at wave 2 (February 2022) using the validated 13-item Health Interest Scale (score range, 13–52), analyzed as a continuous standardized variable. Primary outcome was self-reported all-cause hospitalization during the 12 months preceding wave 3. Secondary outcomes included 14 moderate-to-severe physical symptoms and 14 physician-diagnosed chronic diseases. Results Among 15,519 participants, those with higher health indifference exhibited a paradoxical pattern: despite reporting more moderate-to-severe symptoms (including fever, chest pain, and dyspnea), they had significantly lower healthcare utilization. Each standard deviation increase in health indifference was associated with 18% lower hospitalization (adjusted risk ratio, 0.82; 95% CI, 0.77–0.88) and fewer diagnoses of chronic conditions typically detected through screening. This inverse relationship between symptom burden and healthcare utilization was consistent across all analyses. Conclusions Health indifference predicts paradoxical dissociation, wherein individuals experience and report more symptoms but utilize less healthcare. Lower chronic disease diagnoses likely reflect detection bias from avoided screening rather than improved health.