Community Mental Health Services Nurse Empanelment Continuity and Psychotropic Adherence Discontinuity at Caseload Boundary Thresholds in Ugandan Districts: A Difference-in-Differences Analysis

Ugandan district community mental health services assign psychotropic medication management to nurses whose empanelment lists are capped at fixed caseload thresholds, yet the consequences of crossing those administrative boundaries for adherence continuity remain unexamined. The framework treats the threshold as a treatment assignment rule, defines adherence discontinuity as the change in twelve-month psychotropic possession ratio occurring when a nurse's list crosses the boundary, and specifies the parallel-trends assumption required for identification. Analysis of the identification conditions indicates that threshold crossing is not random with respect to patient acuity, that nurse-level heterogeneity in list management confounds naive comparisons, and that the difference-in-differences estimator recovers the local average treatment effect at the boundary only under explicit exclusion restrictions. The framework proposes three testable propositions linking empanelment discontinuity to adherence gaps, and identifies the data structures required for empirical implementation. The contribution is a specification of when caseload thresholds generate measurable adherence discontinuity and a set of conditions under which district-level empanelment policy can be evaluated without randomised assignment.