Pneumocystis and glucocorticoid use: to prophylax or not to prophylax (and when?); that is the question

Pneumocystis jiroveci is an opportunistic fungus with the ability to cause lethal pneumonia in those with advanced immunosuppression.1 Fortunately, this outcome is preventable with prophylaxis. Unfortunately, however, deciding who is immunosuppressed enough to justify prophylaxis can be a confusing subject, particularly among rheumatology patients where immunosuppression waxes and wanes based on the use of immunosuppressive therapies and the contribution of the underlying inflammatory disease. Foggy notions persist regarding who is at risk, the level of absolute risk where the risk-benefit of using trimethoprim/sulfamethoxazole (TMP/SMX) or other prophylaxis is worthwhile, and when can prophylaxis be safely stopped.2 The article by Park et al published in the Annals of Rheumatic Diseases 3 sheds light on these important questions, such that a picture of how to approach this issue clinically might finally be more clear for the practicing rheumatologist. Given the difficulty studying these questions in a randomised controlled trial fashion, comparative effectiveness studies such as this one might provide the next best thing. In the article, the authors address the following questions: in patients starting high-dose glucocorticoids and taking them greater than 4 weeks, what is the risk of pneumocystic jiroveci pneumonia (PJP) (and the risk factors for it) and how does risk relate to dose? Further, they evaluate the efficacy of TMP/SMX prophylaxis. To answer these questions, they retrospectively identified an institutional cohort of rheumatology patients in Korea treated with ‘high-dose’ glucocorticoids (>30 mg/day) for 4 or more weeks. Within this cohort, they selected patients offered TMP/SMX prophylaxis and compared their incidence of PJP with the remainder of the group that did not receive prophylaxis. There were important underlying differences between the groups, as one might expect, and it was clear that the treating physicians had generally chosen to give TMP/SMX to those they had perceived at higher risk for …