Self-reported and recent claims-based major depressive disorder identifies distinct risk profiles in a nationwide population study.

BACKGROUND: Major depressive disorder (MDD) in population studies is commonly identified from self-reported history or healthcare records, but agreement is often modest and the implications of discordance remain unclear. METHODS: We included 135,287 Taiwan Biobank participants enrolled from 2008 to 2020 whose baseline self-reported depression status was linked to nationwide health insurance claims. Claims-based MDD required at least two outpatient claims or one inpatient claim in the preceding year. Participants were classified as meeting neither definition, self-reported depression only, claims-based MDD only, or both. Healthcare utilization was assessed during the year before and after baseline; all-cause mortality was followed through 2022 using Cox proportional hazards models. RESULTS: Most participants met neither definition (94.9%); 2.4% had self-reported depression only, 1.5% had claims-based MDD only, and 1.2% met both definitions. Claims-positive participants had more recorded physical comorbidities and greater healthcare utilization than the self-reported-only group. During a median 6.41-year follow-up, fully adjusted mortality hazard ratios versus the neither-definition group were 1.34 (95% CI, 1.00-1.79) for self-reported depression only, 1.76 (1.31-2.36) for claims-based MDD only, and 1.87 (1.36-2.58) for both definitions. LIMITATIONS: Self-report reflected lifetime history, whereas claims captured diagnoses from the preceding year. Claims-based identification also depended on healthcare use and diagnostic coding. Findings may not generalize beyond Taiwan's healthcare system. CONCLUSIONS: Self-reported and recent claims-based depression identified partially overlapping populations with different recorded health profiles and mortality estimates. Combining survey and claims data may improve depression phenotyping in population research.