Dementia Ascertainment Source and Place-of-Death Estimates in Taiwan: A Nationwide Linkage Study.

PURPOSE: This study quantified how dementia ascertainment source shapes population-level place of death (POD) estimates among older adults dying with dementia. METHODS: This cross-sectional study (2014-2023) in Taiwan linked death certificates and NHI claims for decedents aged ≥65 years identified with dementia. POD was categorized as hospital, home, long-term care (LTC) facility, or inpatient palliative care unit. Ascertainment-related POD differences were assessed using multinomial logistic regression with generalized estimating equations and average marginal effects. RESULTS: Among 291,652 decedents, NHI claims identified 279,074 individuals (underlying cause of death [UCOD], 24,911; multiple causes of death [MCOD], 43,487). Only 5.2% of decedents were identified by all three sources; 83.4% of NHI-identified cases had no dementia recorded on death certificates. NHI ascertainment was associated with significantly lower (vs. UCOD) adjusted odds of palliative unit (aOR 0.32; 95% CI 0.30-0.33), home (aOR 0.68; 0.66-0.70), and LTC deaths (aOR 0.61; 0.58-0.64). NHI-based identification showed a 13.6-percentage-point higher (vs. MCOD) hospital death probability (95% CI 13.2-14.1). CONCLUSIONS: Dementia ascertainment source defines the dementia decedent population monitored and shapes the POD distribution among dementia decedents. Death-certificate-only ascertainment may underestimate hospital deaths. Multisource linkage reveals source-dependent exclusions relevant to end-of-life assessment and policy planning.