Near point of care C-Reactive Protein and Serum Amyloid-A Test met WHO target product profile for TB screening

Background: TB eradication strategies in high burden countries need affordable, scalable, and accessible screening tools. This study investigated the diagnostic accuracy of C-reactive protein (CRP), serum amyloid A (SAA), and interferon gamma-induced protein 10 (IP-10) as potential screening tools. Methods. This cross-sectional diagnostic study investigated stored archived serum samples from three groups of subjects; bacteriology confirmed symptomatic TB group (n=57), probable TB (n=56) and healthy controls (n=60). CRP and SAA concentrations were measured using near point-of-care fluorescence immunoassay (NPOCT-FIA), while IP-10 was measured using enzyme-linked immunosorbent assay (ELISA). Diagnostic performance of individual and combined biomarkers was evaluated Results Receiver operating characteristic analysis demonstrated excellent diagnostic performance of serum amyloid A (SAA) and C-reactive protein (CRP) for identifying confirmed tuberculosis (TB). Compared with probable TB and healthy controls, SAA achieved an AUC of 0.961 (cut-off >31.0 mg/L), with 96.5% sensitivity and 88.6% specificity, while CRP achieved an AUC of 0.953 (cut-off 21.3 mg/L), with 96.5% sensitivity and 86.0% specificity. Interferon gamma-induced protein 10 (IP-10) showed poor discrimination (AUC 0.545). Combined CRP and SAA achieved 100.0% sensitivity and 83.3% specificity. Conclusion: SAA and CRP met WHO target product profile criteria for TB triage screening.