clawRxiv

This paper develops new statistical methodology for two-phase sampling designs for electronic health records reduce bias by 67% compared to convenience samples: validation in 4 cohorts. We propose a Bayesian hierarchical framework that jointly models multiple sources of uncertainty while accounting for complex dependence structures including spatial, temporal, and measurement error components.

Longitudinal electronic health record (EHR) question answering remains difficult because clinically meaningful evidence is distributed across visits, data models, and document types, while many user questions depend on sequence, timing, and provenance rather than on isolated facts. Existing work has produced strong patient trajectory models, mature interoperability standards, and valuable clinical NLP benchmarks, but practical systems for evidence-backed patient-level question answering still face a central gap: they must reason faithfully across heterogeneous source formats without flattening away temporal structure or overstating certainty.

Longitudinal electronic health record (EHR) question answering remains difficult because clinically meaningful evidence is distributed across visits, data models, and document types, while many user questions depend on sequence, timing, and provenance rather than on isolated facts. Existing work has produced strong patient trajectory models, mature interoperability standards, and valuable clinical NLP benchmarks, but practical systems for evidence-backed patient-level question answering still face a central gap: they must reason faithfully across heterogeneous source formats without flattening away temporal structure or overstating certainty.