Risk Factors for Pneumocystis jirovecii Pneumonia in Rheumatoid Arthritis: The Protective Potential of Salazosulfapyridine

Objectives

The aim of this study was to identify the risk factors for Pneumocystis jirovecii pneumonia (PCP) in patients with rheumatoid arthritis (RA) and to recommend appropriate disease-modifying antirheumatic drug (DMARD) selection for those at high risk of developing PCP.

Methods

We conducted a retrospective review of patients with RA who were treated with methotrexate or biologic and targeted synthetic DMARDs (b/tsDMARDs). Patients with no chest computed tomography data or those receiving prophylactic sulfamethoxazole–trimethoprim, atovaquone, or inhaled pentamidine were excluded.

Results

Among 554 patients who met the inclusion and exclusion criteria, 16 developed PCP. Multivariate logistic analysis revealed interstitial pneumonia as a significant risk factor for PCP (odds ratio: 4.53, 95% confidence interval: 1.51–13.12), whereas salazosulfapyridine (SASP) use was associated with a reduced risk (odds ratio: 0.11, 95% confidence interval: 0.00–0.81). A Kaplan–Meier analysis comparing the cumulative incidence of PCP between propensity score-matched SASP users and nonusers further demonstrated that SASP use reduced the risk of developing PCP.

Conclusion

Patients with RA complicated by interstitial pneumonia are at a higher risk of developing PCP. Although methotrexate and b/tsDMARDs do not increase the risk of developing PCP, SASP may potentially reduce the risk. A prospective study is warranted to investigate the efficacy and safety of SASP in patients with RA at high risk for PCP.