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

摘要

The objective of this prospective cross-sectional study, conducted at a national referral hospital in Kampala, Uganda, was to determine diagnostic performance of serum C-reactive protein (CRP) as a triage test for tuberculosis (TB) among HIV-seronegative inpatients. We calculated the sensitivity, specificity, positive and negative likelihood ratios, and positive and negative predictive values to determine the diagnostic performance of a CRP enzyme-linked immunosorbent assay (ELISA) (Eurolyser) in comparison to that of a reference standard of Mycobacterium tuberculosis culture on two sputum samples. We constructed receiver operating curves and reported performance in reference to the manufacturers cutoff and also to a threshold chosen to achieve sensitivity of >90, in accordance with the WHO's target-product profile for a triage test. Among 119 HIV-seronegative inpatients, 46 (39) had culture-positive pulmonary TB. In reference to M. tuberculosis culture, CRP had a sensitivity of 78 (95 confidence interval CI, 64 to 89) and a specificity of 52 (95 CI, 40 to 64) at the manufacturer's threshold of 10 mg/liter. At a threshold of 1.5 mg/liter, the sensitivity was 91 (95 CI, 79 to 98) but the specificity was only 21 (95 CI, 12 to 32). Performance did not differ when stratified by illness severity at either threshold. In 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.