Implementation determinants of rapid diagnostics tests for fever management in sub-Saharan Africa: a mixed-studies...

Rapid diagnostic tests (RDTs) have the potential to improve fever management in sub-Saharan Africa (SSA). However, fulfilling this potential can be hindered by factors beyond test performance, impacting their successful implementation. The Non-adoption, Abandonment, Scale-up, Spread, and Sustainability (NASSS) framework offers a structured approach to exploring such determinants and underlying mechanisms. In this mixed-studies systematic review, we searched 8 electronic databases for studies to map and synthesise evidence on implementation determinants of RDTs use in SSA. Two authors independently conducted study selection and data extraction. The quality of included studies was assessed using the Mixed Methods Appraisal Tool (v2018), and the Joanna Briggs Institute critical appraisal checklist for systematic reviews and research syntheses. We applied a framework synthesis guided by the NASSS framework. This review included 48 publications covering 33 countries in SSA and revealed several themes and complexities, whose interdependencies show variation in the adoption and long-term use of RDTs in SSA. The synthesis identified 35 higher-order themes, with the majority of evidence concentrated on adoption and peri-implementation rather than long-term adaptation. Across settings, sustained RDT uptake was constrained by: increased health worker workload, limited integration into existing clinical workflows, misalignment between test results and clinical judgement, and unreliable supply chains. Evidence on how these barriers were addressed over time was sparse, revealing a gap in implementation research. Furthermore, the single-disease focus of RDTs was found to limit their utility, given that patients often present with undifferentiated fever or multiple conditions. To optimise future implementation of RDTs, their design and health system adoption need to be informed by clinical need and integrated into care pathways, including the development of RDTs that address multiple diagnoses.