EFFECT OF AEROSOLIZED PENTAMIDINE PROPHYLAXIS ON THE DIAGNOSIS OF PNEUMOCYSTIS-CARINII PNEUMONIA BY INDUCED SPUTUM EXAMINATION IN PATIENTS INFECTED WITH THE HUMAN-IMMUNODEFICIENCY-VIRUS

This study assessed the effect of aerosolized pentamidine prophylaxis on the clinical presentation and diagnostic sensitivity of induced sputum examination for Pneumocystis carinii pneumonia. Between January 1, 1988 and October 27, 1990, 348 induced sputum examinations were performed as the initial diagnostic procedure for P. carinii pneumonia in patients infected with the human immunodeficiency virus (HIV). Medical records were reviewed for all induced sputum examinations, and the study group consisted of patients who either had not received prophylactic therapy (n = 193) or had received aerosolized pentamidine prophylaxis (n = 126). A total of 29 induced sputum examinations in patients receiving either other prophylactic regimens or ongoing therapy for previously documented P. carinii pneumonia were excluded from the study group. A total of 72 consecutive episodes of P. carinii pneumonia were subsequently documented by induced sputum examination (n = 54), bronchoalveolar lavage (n = 16), thoracocentesis (n = 1), or autopsy (n = 1). A total of 44 episodes occurred in patients who had not received antipneumocystis prophylaxis, and 28 episodes occurred in patients who had received aerosolized pentamidine. Of patients capable of producing a sputum specimen for analysis, induced sputum examination had a significantly lower diagnostic yield of 64.3% in patients who had received aerosolized pentamidine prophylaxis compared with 92.3% in patients who did not receive prophylaxis (p < 0.02, Fisher's exact test). When the data were analyzed on an intention to treat basis, although there was a trend suggesting a lower overall yield in the aerosolized pentamidine patients, the difference was not statistically significant (64.3 versus 81.8%, p = 0.17, Fisher's exact test). There was no significant difference in duration of symptoms, alveolar-arterial oxygen gradient, presenting radiographic manifestations, or burden of organisms (in patients with positive induced sputum examinations) between the two groups. However, there was a trend toward an increased incidence of focal upper lobe infiltrates in the aerosolized pentamidine group (p = 0.054, Fisher's exact test). We conclude that aerosolized pentamidine prophylaxis is associated with a significantly lower diagnostic yield (64.3%) of induced sputum examination for P. carinii pneumonia in HIV-infected patients if a specimen is obtained for analysis. Nevertheless, its yield is high enough such that an induced sputum examination should still be considered the initial diagnostic procedure for suspected P. carinii pneumonia in these patients.