Efficacy of once-weekly dapsone dosing for Pneumocystis jirovecii pneumonia prophylaxis post transplantation.

BACKGROUND: Pneumocystis jirovecii pneumonia (PCP) remains a concern after organ transplantation. In 2005, the University of Kentucky (UK) Transplant Center implemented a novel dosing regimen of weekly dapsone as an alternative for patients with contraindications or intolerability to trimethoprim-sulfamethoxazole (TMP-SMZ), which remains the drug of choice. The purpose of this study was to compare the efficacy of weekly dapsone with TMP-SMZ in preventing PCP post transplantation.

METHODS: A single-center, cohort, retrospective review of kidney and liver transplant patients from January 2005 to December 2012 was conducted. Patients who were identified as dapsone cases were matched in a 1:1 ratio with TMP-SMZ controls based on type of transplant, age, primary diagnosis, and gender. The primary endpoint assessed was the diagnosis of PCP at 6 and 12 months post transplant.

RESULTS: A total of 158 patients were included in the study. No documented cases of PCP occurred in either study group at 6 or 12 months (P = 1.0). In dapsone patients 35 (44%) cases of breakthrough infection occurred, compared to 24 (30%) in the TMP-SMZ group (P = 0.07) within 12 months post transplant. In the dapsone group, 52 (65%) patients were hospitalized within 6 months post transplant compared to 36 (46%) patients in the TMP-SMZ group (P = 0.01). Similar results were seen in patients hospitalized within 12 months post transplant; 49% of patients were switched from TMP-SMZ to dapsone owing to renal dysfunction.

CONCLUSION: No documented cases of PCP occurred in either study group. Future studies are warranted to show the efficacy of weekly dapsone dosing compared to other PCP prophylaxis regimens.