Causal Pathways Linking Disability Rehabilitation Health Service Continuity to Referral Completion in Uganda: A Multilevel Mediation Design

Referral non-completion remains a persistent failure point in disability rehabilitation pathways in Uganda, yet most analytic treatments collapse continuity of care into a single patient-level exposure and treat completion as an individual binary outcome. That specification cannot recover how facility routines and district referral architectures jointly shape whether continuity translates into completed onward care. This methodological article develops a multilevel mediation design in which service continuity operates simultaneously as a within-facility patient experience and as a between-facility organisational property, with candidate mediators specified at the patient, facility and district levels. Drawing on continuity theory, causal mediation principles and hierarchical modelling, the design distinguishes direct pathways from continuity to referral completion from indirect pathways running through appointment coordination, transport and escort support, information transfer across levels of care, and district supervisory intensity. Identification conditions, measurement options compatible with routine health-information systems and disability registers, and nesting assumptions appropriate to Uganda's public referral hierarchy are stated explicitly. The article does not report empirical estimates; it specifies what a correctly designed multilevel mediation analysis would be able to identify, under what assumptions, and where those assumptions would fail in fragmented rehabilitation markets. The contribution is a discipline-ready analytic architecture for disability and rehabilitation health services research rather than a claim about observed effects.