Meta-analysis of diagnostic procedures for Pneumocystis carinii pneumonia in HIV-1-infected patients

Sputum induction is a simple and noninvasive procedure for Pneumocystis carinii pneumonia (PCP) diagnosis in human immunodeficiency virus-1-positive patients, although less sensitive than bronchoalveolar lavage (BAL). In order to obtain an overview of the diagnostic accuracy of sputum induction, a systematic review and meta-analysis of studies reporting the comparative sensitivity and specificity of BAL (the “gold standard”) and sputum induction was performed. The odds ratio and related 95% confidence interval were calculated using summary receiving operating characteristic curves as well as fixed-effect and random-effect models. Based on pooled data, the negative and positive predictive values were calculated for a range of PCP prevalence using a Bayesian approach. Seven prospective studies assessed the comparative accuracy of BAL and sputum induction. On the whole, sputum induction demonstrated 55.5% sensitivity and 98.6% specificity. The sensitivity of sputum induction was significantly higher with immunofluorescence than with cytochemical staining (67.1 versus 43.1%). In settings of 25–60% prevalence of PCP, the positive and negative predictive values ranged 86–96.7 and 66.2–89.8, respectively, with immunofluorescence, and 79–94.4 and 53–83.5% with cytochemical staining. In conclusion, in a setting of low prevalence of Pneumocystis carinii pneumonia, sputum induction, particularly with immunostaining, appears to be adequate for clinical decision-making.