Sulfamethoxazole-trimethoprim (SMX-TMP) is recommended first-line for Pneumocystis jirovecii pneumonia (PJP) prophylaxis in kidney transplant recipients. In cases of sulfa allergy or intolerance, our center utilizes dapsone 100 mg once weekly as alternative prophylaxis. As both agents have the potential to cause hematologic abnormalities, we sought to compare hematologic effect profiles of weekly dapsone versus SMX-TMP in kidney transplant recipients.

This retrospective, single-center, cohort study included kidney transplant recipients who received SMX-TMP or dapsone for PJP prophylaxis. The primary endpoint was the change in hemoglobin from baseline to nadir. Secondary endpoints included hemoglobin and white blood cell (WBC) count at 1, 3, and 6 months posttransplant, time to hemoglobin nadir, neutropenia incidence, and ANC nadir. In addition, we evaluated the incidence of hospital readmission, bacteremia, and PJP.

A total of 509 kidney transplant recipients were included (334 SMX-TMP vs. 175 dapsone). Median decrease in hemoglobin (g/dL) from baseline to nadir was greater in the dapsone group (0 SMX-TMP vs. -0.20 dapsone; p = 0.046). Mean absolute hemoglobin count was lower in the dapsone group at all time points. There was no difference in WBC, ANC nadir, or incidence of neutropenia at any time point between groups. Greater frequencies in readmissions (30.7% vs. 55.7%; p < 0.001) and bacteremia (3.6% vs. 10.8%; p < 0.001) were observed in the dapsone arm.

Once-weekly dapsone is associated with statistically significant decreases in hemoglobin when compared to SMX-TMP in a kidney transplant cohort, which may be clinically relevant in select patients. Dapsone use may also increase infection risk.