Martin and colleagues1 recently published results of a retrospective chart review evaluating the effectiveness of three regimens for the prophylaxis of Pneumocystis carinii pneumonia (PCP). They reported an incidence of relapse for trimethoprimsulfamethoxazole (double-strength tablet orally twice a day, given 3 days per week), dapsone (50 mg every day), and aerosolized pentamidine (300 mg once every month) of 0%, 6.5%, and 13.6%, respectively. Trimethoprim-sulfamethoxazole was the primary prophylactic regimen. The authors concluded that trimethoprim-sulfamethoxazole was the most effective regimen for primary and secondary prophylaxis of PCP.
We have several concerns regarding the validity of the study design and conclusions. One potential complicating factor in this study is the nonrandomized nature of patient selection for each prophylactic regimen. Were there any specific exclusion criteria, such as asthma (steroid therapy), recent prior PCP treatment, or expected survival of less than 1 week?2,3 No mention of comparability among the three groups