Equity Effects of Congenital Heart Disease Adults Coverage on Avoidable Care Delays in Kenya: A Target-Trial Emulation

Adult congenital heart disease (ACHD) care in Kenya is characterised by late presentation, fragmented services and profound inequity, yet the extent to which expanded service coverage reduces avoidable delays across social strata remains unknown. We argue that conventional before-after evaluations conflate secular trends with intervention effects and obscure distributional consequences by averaging over heterogeneous populations. The proposed design specifies eligibility criteria, treatment assignment based on geographic access to accredited centres, and a primary outcome of delay from symptom onset to specialist evaluation, with avoidable delay defined through clinical benchmarks. We articulate how observational data from routine health information systems and civil registration could be structured to emulate the target trial, addressing confounding through propensity score weighting and time-varying exposures. The framework predicts that coverage expansion will reduce mean delays but may widen absolute inequities if referral networks disproportionately benefit urban, affluent patients. We conclude that equity-focused target-trial emulation offers a rigorous basis for evaluating ACHD policy in Kenya, and we identify design parameters that must be measured to support causal inference in this setting.