Randomized study of sulfamethoxazole-trimethoprim versus aerosolized pentamidine for secondary prophylaxis of Pneumocystis carinii pneumonia in patients with AIDS.

In a prospective, randomized open-label trial, the efficacy of sulfamethoxazole-trimethoprim (SMX-TMP) 400/80 mg b.i.d. was compared with the efficacy of aerosolized pentamidine (AP) 60 mg every 2nd week as secondary prophylaxis (SP) against recurrence of Pneumocystis carinii pneumonia (PCP) in AIDS patients. 94 patients participated in the study, 47 in each group. The patients were observed for a mean period of 17.2 months. PCP recurred in the AP group in 8 cases, while 1 relapse occurred in the SMX-TMP group. The one-year cumulative relapse rate was 9.0% (95% CI 0-19%) in the AP group compared with 2.4% (95% CI 0-8%) in the SMX-TMP group (p < 0.05). The odds ratio was 4.2 (95% CI 0.5-39.8) in favour of SMX-TMP. Furthermore, we found a tendency towards a protective effect against toxoplasmosis in the SMX-TMP group, though there was no difference in survival between the two groups. There was no statistical difference in frequency of crossover from one therapy form to the other. Based on these data we recommend SMX-TMP for secondary PCP prophylaxis.