Induced sputum for diagnosing Pneumocystis carinii pneumonia in HIV patients: new data, new issues

The complexity of bronchoalveolar lavage (BAL) has motivated the search for noninvasive methodology to retrieve specimens for detecting the presence of various pulmonary diseases. Induced sputum (IS) has been shown to be a reliable tool in terms of sensitivity and specificity comparable to BAL. Investigators from institutions worldwide have published several reports providing evidence in support of one or the other or a combination of both approaches. Among them are studies demonstrating the sensitivity and specificity of IS in diagnosing Pneumocystis carinii pneumonia (PCP) in patients with acquired immunodeficiency syndrome (AIDS). In 1996, highly active antiretroviral therapy was introduced for routine use and the morbidity from opportunistic infections decreased sharply. An earlier study showed that cost-effectiveness depends on the prevalence of a given condition in the population. More recent studies have confirmed that prophylaxis against PCP can be stopped after increasing the CD4 cell count, thus reducing the attractiveness of IS as a preferred method for monitoring the course of disease. This review presents a brief description of the evolution of the bronchoalveolar lavage versus induced sputum controversy and reconsiders the strengths and weaknesses of the earlier arguments in light of newer data that have emerged with regard to Pneumocystis carinii pneumonia in acquired immunodeficiency syndrome.