Test performance of blood beta-glucan for Pneumocystis jirovecii pneumonia in patients with AIDS and respiratory symptoms

aDivision of Infectious Diseases, Brigham and Women's Hospital and Harvard Medical School bHarvard School of Public Health, Boston, Massachusetts cDivision of Infectious Diseases and Department of Medicine, Stanford University School of Medicine, Stanford, California dAssociates of Cape Cod, East Falmouth, Massachusetts, USA eSchool of Medicine, University College Dublin, Dublin, Ireland fDivision of Infectious Diseases and Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA. *Current affiliation: Division of Allergy and Infectious Diseases, University of Washington, Seattle, Washington, USA.
AIDS (London, England) (Impact Factor: 6.56). 03/2013; 27(6):967-972. DOI: 10.1097/QAD.0b013e32835cb646
Source: PubMed

ABSTRACT OBJECTIVE:: The objective of this study was to define the test characteristics of plasma beta-glucan for diagnosis of Pneumocystis jirovecii pneumonia (PCP) in AIDS patients with respiratory symptoms. DESIGN:: Analysis of baseline blood samples in a randomized strategy study of patients with acute opportunistic infections, limited to participants with respiratory symptoms. METHODS:: Participants in the 282-person ACTG A5164 trial had baseline plasma samples assayed for beta-glucan testing. As part of A5164 trial, two study investigators independently adjudicated the diagnosis of PCP. Respiratory symptoms were identified by investigators from a list of all signs and symptoms with an onset or resolution in the 21 days prior to or 14 days following study entry. Beta-glucan was defined as positive if at least 80 pg/ml and negative if less than 80 pg/ml. RESULTS:: Of 252 study participants with a beta-glucan result, 159 had at least one respiratory symptom, 139 of whom had a diagnosis of PCP. The sensitivity of beta-glucan for PCP in participants with respiratory symptoms was 92.8% [95% confidence interval (CI) 87.2-96.5], and specificity 75.0% (95% CI 50.9-91.3). Among 134 individuals with positive beta-glucan and respiratory symptoms, 129 had PCP, for a positive predictive value of 96.3% (95% CI 91.5-98.8). Fifteen of 25 patients with a normal beta-glucan did not have PCP, for a negative predictive value of 60% (95% CI 38.7-78.9). CONCLUSION:: Elevated plasma beta-glucan has a high predictive value for diagnosis of PCP in AIDS patients with respiratory symptoms. We propose an algorithm for the use of beta-glucan as a diagnostic tool on the basis of the pretest probability of PCP in such patients.

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