Use of β-D-glucan in diagnosis of suspected Pneumocystis jirovecii pneumonia in adults with HIV infection.

Abstract

An elevated serum (1-3)-β-D-glucan (BDG) concentration has high sensitivity for a diagnosis of Pneumocystis pneumonia (PCP) in people with HIV (PWH). At the current manufacturer-recommended positive threshold of 80 pg/mL (Fungitell), specificity for PCP is variable and other diagnostic tests are required. We evaluated the utility of serum BDG for diagnosis of suspected PCP in PWH at three inner-London hospitals to determine BDG concentrations for diagnosis and exclusion of PCP. From clinical case records, we abstracted demographic and clinical information and categorised patients as having confirmed or probable PCP, or an alternative diagnosis. We calculated sensitivity, specificity and positive predictive value (PPV) of serum BDG concentrations >400pg/mL and negative predictive value (NPV) of BDG <80pg/mL. 76 patients were included; 29 had laboratory-confirmed PCP, 17 had probable PCP and 30 had an alternative diagnosis. Serum BDG >400pg/mL had a sensitivity of 83%, specificity of 97% and PPV 97% for diagnosis of PCP; BDG <80pg/mL had 100% NPV for exclusion of PCP. In PWH with suspected PCP, BDG <80pg/mL excludes a diagnosis of PCP, whereas BDG concentrations >400pg/mL effectively confirm the diagnosis. Values 80-400pg/mL should prompt additional diagnostic tests.