Diagnostic accuracy and clinical role of rapid C-reactive protein testing in HIV-infected individuals with presumed tuberculosis in South Africa

Abstract

To determine the accuracy and role of rapid C-reactive protein (CRP) testing in human immunodeficiency virus (HIV) infected individuals with presumed tuberculosis (TB). We enrolled HIV-infected adults (≥18 years)with a cough of ≥2 weeks and negative sputum smears for acid-fast bacilli in KwaZulu-Natal, South Africa. Participants were evaluated for pulmonary TB (PTB) by a nurse with rapid CRP, and independently by a physician by chest radiograph. Rapid CRP test results were compared with laboratory CRP and sputum sent for confirmation of TB. Among 93 participants, 55 (59%) were female, the mean age was 35 years, and the median CD4 count was 177/mm3. Forty-five (54%) participants were diagnosed with PTB. Diagnostic sensitivity and specificity were respectively 95% (95%CI 74–99) and 51%(95%CI 35–66) for rapid CRP >8 mg/l, 87% (95%CI 73–96) and 53% (95%CI 38–68) for nurse assessment, and 69% (95%CI 52–83) and 76% (95%CI 61–87) for physician examination. Combining a negative rapid CRP(≤8 mg/l) with nurse and physician assessments reduced the post-test probability of PTB from 22% to 6% and from 32% to 6%, respectively. Rapid CRP testing helped exclude PTB,and may be a valuable test in assisting nurses and physicians in TB-endemic regions.