Evaluating the risk-to-benefit ratio of using cotrimoxazole as a pneumocystis pneumonia preventative intervention among pemphigus patients treated with rituximab: A retrospective study with 494 patients.

Rituximab is widely used as the first-line treatment for pemphigus patients. Since it depletes the B cells, it increases the risk of infections. Here, we evaluated the prophylactic efficacy of cotrimoxazole in decreasing the risk of pneumocystis pneumonia (PCP) infection in the pemphigus patients treated with rituximab. The medical records of confirmed pemphigus patients receiving rituximab were evaluated in two groups; those who received cotrimoxazole as a prophylactic after rituximab and patients who only received rituximab without any prophylaxis. The occurrence of PCP infection was determined in each group and compared. Medical records of 494 patients, including 301 women and 193 men, with the mean age of 46.74 years were analyzed. The phenotypes of the disease were mucocutaneous (n = 364), mucosal (n = 88), and cutaneous (n = 42). Among them, 235 cases had received cotrimoxazole as a prophylaxis and 259 patients did not. The incidence of PCP in total patients was 2 (0.4%), one in each group. Accordingly, no significant difference was observed in the incidence of PCP between two groups (p = 0.84). Also, no cotrimoxazole-related side effect was observed in the treated group. It seems that due to the low incidence of PCP in pemphigus patients treated with rituximab, prophylactic cotrimoxazole therapy is not necessary and it only increases the overall therapy cost and might cause cotrimoxazole-related adverse effects in some patients. However, regarding its probable beneficial effect in patients with long-term history of immunosuppressive therapy, more studies are required.