To Örebro University

BACKGROUND: Recent studies have reported that reduced dose trimethoprim-sulfamethoxazole (TMP-SMX) may be effective in the treatment of Pneumocystis jirovecii pneumonia (PJP) but data is lacking for patients with hematologic malignancies.

METHODS: This retrospective study included all adult hematologic patients with PJP between 2013 and 2017 at six Swedish University Hospitals. Treatment with 7.5-15 mg TMP/kg/day (reduced dose) was compared with >15-20 mg TMP/kg/day (standard dose), after correction for renal function. The primary outcome was the change in respiratory function (ΔPaO2/FiO2) between baseline and day 8. Secondary outcomes were clinical failure and/or death at day 8 and death at day 30.

RESULTS: Out of a total of 113 included patients, 80 patients received reduced dose, and 33 patients received standard dose. The overall 30-day mortality in the whole cohort was 14%. There were no clinically relevant differences in ΔPaO2/FiO2 at day 8 between the treatment groups, neither before nor after controlling for potential confounders in an adjusted regression model (-13,6 mmHg [95% CI -56,7-29,5] and -9,4 mmHg, [95% CI -50.5-31.7], respectively). Clinical failure and/or death at day 8 and 30-day mortality did not differ significantly between the groups, 18% vs. 21% and 14% vs. 15%, respectively. Among patients with mild to moderate pneumonia, defined as PaO2/FiO2>200 mmHg, all 44 patients receiving reduced dose were alive at day 30.

CONCLUSION: In this cohort of 113 patients with hematologic malignancies, reduced dose TMP-SMX was effective and safe for treating mild to moderate PJP.