• rheumatoid arthritis
• disease activity
• treatment

We read with great interest the recent article by Park et al 1 and appreciate the authors’ efforts to assess the benefit and safety of trimethoprim-sulfamethoxazole (TMP/SMX) as primary prophylaxis for pneumocystis pneumonia in patients with rheumatic diseases, exposed to prolonged high-dose glucocorticoids.

However, we would like to point out one concern in the incidence of adverse drug reactions related to TMP/SMX prophylaxis. Despite its efficacy, TMP/SMX could induce adverse events that could cause some patients to discontinue prophylaxis and increase the risk for Pneumocystis jirovecii pneumonia. There could be a disease gap for the development of adverse events, and higher risk was indicated in patients with systemic lupus erythematosus (SLE) compared with other rheumatic diseases. In patients with SLE, the reaction rate was estimated to be up to 27.3%–53%2–5 and anti-Ro/SS-A antibody was especially warned to be a prognostic factor.2 In addition, a prophylactic regimen is also important to assess safety. This is because adverse events requiring discontinuation of TMP/SMX prophylaxis were higher in patients with usual prophylaxis of a single-strength TMP/SMX tablet daily compared with graded administration.2 6 For these reasons, detailed description revealing safety profiles based on individual diseases and prophylactic regimens would be required.

In conclusion, we acknowledge the interesting results provided by the authors, confirming the safety and efficacy of TMP/SMX prophylaxis. However, we believe that evaluating safety in patients with SLE would guide the readers in having a better understanding regarding the TMP/SMX prophylaxis in patients with rheumatic diseases.