Community Mental Health Services Clinic Consolidation and Travel Burden Among Rural Outpatients in Zambian Districts: A Difference-in-Differences Analysis

The consolidation of community mental health clinics is frequently justified by economies of scale and supervision quality, yet the travel burden it imposes on rural outpatients is rarely quantified. The framework specifies treatment and comparison districts, defines pre- and post-consolidation periods, and derives the estimator under explicit assumptions about parallel trends, treatment timing and distance measurement. A worked illustration using the DHS Program indicator 'Knowledge of any method of contraception among married women' (38 African countries, 162 country-survey observations, 1986-2025, mean 91.776, SD 11.342) demonstrates the arithmetic of the estimator and the reporting conventions it requires. Travel burden is a measurable and policy-relevant outcome of consolidation, that its estimation requires attention to differential attrition and to the distinction between distance and time, and that the difference-in-differences design is well suited to the question but vulnerable to consolidation that is endogenous to local demand. The contribution is a transferable estimation template for district-level mental health planners, not a set of empirical estimates.