Efficacy and safety of a low-dose sulfamethoxazole/trimethoprim regimen in preventing pneumocystis pneumonia: A retrospective study using a large-scale electronic medical record database.

INTRODUCTION

Sulfamethoxazole/trimethoprim (ST) is a first-line drug for preventing pneumocystis pneumonia (PCP). Several small-scale studies have suggested the usefulness of the low-dose regimen of ST (200/40 mg/day) over the standard-dose one (400/80 mg/day). Thus, this study aimed to investigate the efficacy and safety of low-dose and standard-dose regimens of ST in preventing PCP in patients with non human immunodeficiency virus infection using a large-scale electronic medical record database.

METHODS

This retrospective study included patients who received ST prophylaxis for PCP registered in the RWD database between June 2007 and February 2023. Patients received either standard-dose (400/80 mg/day) or low-dose (200/40 mg/day) regimen groups. The incidence of cases initiated PCP therapeutic dose (ci-PCPTD) (ST ≥ 3600/720 mg/day) and adverse events (AEs) was evaluated, and risk factors for ci-PCPTD were investigated.

RESULTS

A total of 11,384 patients received the standard-dose, whereas 7973 received the low-dose regimen groups. No significant difference in the cumulative incidence of ci-PCPTD was observed between the standard-dose (0.67%) and low-dose regimen group (0.47%). Lung disease was a significant risk factor for ci-PCPTD. The cumulative incidence of ci-PCPTD in patients with acute exacerbation of interstitial pneumonia was 1.3% in both groups, and no significant difference was observed between the two groups. The low-dose regimen group had a lower incidence of all AEs than the standard-dose regimen group.

CONCLUSION

These results based on a large-scale electronic medical record database provide important evidence supporting the clinical significance of low-dose regimen of ST.