C-Reactive Protein for Active Tuberculosis Among Inpatients without HIV in Uganda: A Diagnostic Accuracy Study.

Setting: National referral hospital in Kampala, UgandaObjective: To determine diagnostic performance of serum C-reactive protein (CRP) as a triage test for tuberculosis (TB) among HIV-seronegative inpatients.Design: Prospective cross-sectional study. We calculated sensitivity, specificity, positive and negative likelihood ratios, and positive and negative predictive values to determine the diagnostic performance of a CRP ELISA assay (Eurolyser), in comparison to a reference standard of Mycobacterium tuberculosis (Mtb) culture on two sputum samples. We constructed receiver operating curves and reported performance in reference to the manufacturer's cutoff and also to a threshold chosen to achieve sensitivity >90%, in accordance with WHO's target-product profile for a triage test.Results: Among 119 HIV-seronegative inpatients, 46 (39%) had culture-positive pulmonary TB. In reference to Mtb culture, CRP had sensitivity of 78% (95% confidence interval (CI) 64-89%) and specificity of 52% (95% CI 40-64%) at the manufacturer's threshold of 10 mg/L. At a threshold of 1.5 mg/L, sensitivity was 91% (95% CI 79-98%), but specificity was only 21% (95% CI 12-32%). Performance did not differ when stratified by illness severity at either threshold.Conclusion: Among HIV-seronegative inpatients, CRP testing performed substantially below targets for a TB triage test. Additional studies among HIV-seronegative individuals in clinics and community settings are needed to assess the utility of CRP for TB screening.