C-Reactive Protein Testing for Active Tuberculosis among Inpatients without HIV in Uganda: a Diagnostic Accuracy Study

Abstract

Setting: National referral hospital in Kampala, Uganda Objective: 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.

Clinical Features and Risk Factors for Active Tuberculosis in Takayasu Arteritis: A Single-Center Case-Control Study

“…Similar results were observed in other studies in which the combination of CRP and other biomarkers showed superior performance for TB identification (18,19). However, a recent diagnostic accuracy study excluded the utility of CRP as a TB triage test due to its low specificity (20). Therefore, additional studies are still needed to assess the utility of CRP for TB screening, especially in TAK patients.…”

Blood-based host biomarker diagnostics in active case finding for pulmonary tuberculosis: A diagnostic case-control study

“…High accuracy has been reported in some studies of HIV co-infected patients [ 21 , 22 ], though there have been fewer studies assessing screening among HIV-negative individuals, and performance has generally been poorer. A recent study among HIV-negative inpatients in Uganda found specificity of 21% at sensitivity of 91% [23] . We are unaware of any studies assessing C-reactive protein in the context of mass screening for active case detection.…”

Blood-based host biomarker diagnostics in active case finding for pulmonary tuberculosis: a diagnostic case-control study

“…A recent study among HIV-negative inpatients in Uganda found specificity of 21% at sensitivity of 91%. 23 We are unaware of any studies assessing C-reactive protein in the context of mass screening for active case detection. We found the AUC to be 0.79 for the point-of-care CRP test in our study, consistent with the moderate accuracy previously reported in HIV-uninfected individuals.…”