Intimate-partner-violence screening mandates and antiretroviral adherence among women in South African clinics: a difference-in-differences evaluation of health-system detection effects

South African HIV programmes have introduced intimate-partner-violence (IPV) screening mandates in antiretroviral therapy (ART) clinics on the premise that detection improves adherence, yet the causal pathway from mandated enquiry to viral suppression remains poorly specified. The framework distinguishes three mechanisms — disclosure-mediated support, surveillance-mediated stigma, and documentation-mediated continuity — and specifies the conditions under which each dominates. Using the DHS Program indicator 'Knowledge of any method of contraception among married women' (FP_KMET_W_ANY) as a benchmark for the measurement properties of self-reported reproductive-health indicators across 38 African countries (162 country-survey observations, 1986–2025; mean 91.776, SD 11.342), the paper calibrates the precision required for a credible difference-in-differences design. Detection effects are likely to be small relative to the measurement error inherent in self-reported adherence, that clinic-level screening intensity is the binding constraint on identification, and that the parallel-trends assumption is threatened by concurrent ART-guideline changes. The contribution is a specification of the detection-effect estimand and a set of design conditions under which South African clinic data could support credible causal inference.