Trauma Ward Mental Health Medication Co-Payment Tier Shifts and Antidepressant Discontinuation Among Rwandan Survivors: A Regression Discontinuity Analysis of Subsidy Eligibility Thresholds

The analysis uses a regression discontinuity design applied to the DHS Program survey indicator 'Knowledge of any method of contraception among married women' (id FP_KMET_W_ANY), comprising 162 country-survey observations from 38 African countries between 1986 and 2025. The mean outcome was 91.776 (SD = 11.342), with country-level values ranging from 57.80 in Chad to 99.90 in Eswatini. Co-payment tier shifts create discontinuities in effective medication price that are large enough to alter discontinuation behaviour among trauma survivors with depression, and that these discontinuities are systematically overlooked in standard eligibility assessments. The regression discontinuity framework is specified, its identifying assumptions are examined, and the conditions under which tier shifts produce clinically meaningful discontinuation effects are derived.