Causal Pathways Linking Cell Biology Core Life Service Continuity to Referral Completion in Uganda: A Multilevel Mediation Design

Referral completion in Ugandan district health systems remains a persistent bottleneck, yet the mechanisms through which continuity of cell biology core life services—laboratory diagnostics, specimen transport, and result communication—influence a patient's passage through the referral chain are poorly specified. We argue that service continuity operates through two distinct mediators: diagnostic confidence among referring clinicians and patient trust in the referral process. A multilevel mediation design is proposed to disentangle these pathways, accommodating the nested structure of patients within facilities within districts. The framework integrates causal mediation analysis with a counterfactual approach to unobserved confounding, and specifies measurement strategies for each construct. The principal contribution is a testable theoretical model that reframes referral failure not as a patient-level behavioural deficit but as a systems-level discontinuity in the biological information infrastructure. This design offers a rigorous template for evaluating interventions aimed at strengthening diagnostic service continuity and provides a foundation for empirical work in Ugandan settings.