Economic Evaluation of Implementing SD Biosensor Antigen Detecting SARS-COV-2 Rapid Diagnostic Tests in Kenya

The COVID-19 pandemic has created a need to rapidly scale-up testing services. In Kenya, services for SARS-CoV-2 nucleic acid amplifying test (NAAT) have often been unavailable or delayed, precluding the clinical utility of the results. The introduction of antigen-detecting rapid diagnostic tests (Ag-RDT) has had the potential to fill at least a portion of the ‘testing gap’. We, therefore, evaluated the cost-effectiveness of implementing SD Biosensor Antigen Detecting SARs-CoV-2 Rapid Diagnostic Tests in Kenya. We conducted a cost and cost-effectiveness analysis using a decision tree model following the Consolidated Health Economic Evaluation Standards (CHEERS) guidelines under two scenarios: first comparing Ag-RDT as a first-line diagnostic followed by NAAT confirmation of negatives versus delayed NAAT testing only; second comparing Ag-RDT to clinical judgment where NAAT was unavailable. We employed a societal perspective with a time horizon of patient care episodes. Cost and outcomes data were obtained from primary and secondary sources, with robustness assessed through one-way and probabilistic sensitivity analyses. At 10% COVID-19 prevalence, implementing Ag-RDT with confirmatory NAAT for negatives was more costly (US$1,336,231.13 vs US$1,107,117.83) but more effective in averting DALYs (1998.97 vs 2236.49) than delayed NAAT testing alone, yielding an ICER of US$964.63 per DALY averted—below Kenya's cost-effectiveness threshold of US$1003.4. In settings without NAAT access, Ag-RDT was less costly (US$998,260.67 vs US$1,261,230.78) though less effective than clinical judgment at prevalence levels below 16.25%. These findings suggest that implementing Ag-RDTs represents a cost-effective strategy in settings with delayed NAAT access and a cost-saving approach where NAAT is unavailable, providing evidence-based guidance for diagnostic resource allocation in resource-limited settings.