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Many clinicians routinely prescribe sulfamethoxazole-trimethoprim (SMX-TMP) or another agent to prevent the development of Pneumocystis jirovecii pneumonia (PCP) in patients receiving immunosuppressive medications. Evidence justifying such a policy is sparse. The authors of this retrospective study examined the frequency of PCP in 198 HIV-negative patients who received immunomodulatory medications for dermatologic disorders, such as psoriasis, dermatomyositis, vasculitis, and pemphigoid.
Systemic corticosteroids, methotrexate, antimalarials, and azathioprine were the most common immunosuppressive medications used by these patients; approximately 25% received a biologic agent, such as etanercept. About 25% were concurrently receiving a prophylactic medication to prevent PCP. During an average follow-up of 8 years, PCP developed in only one patient not receiving PCP prophylaxis (0.7% incidence). Serious reactions to the PCP-preventive medication developed in 6% of SMX-TMP recipients and 37% of dapsone recipients.
Lehman JS and Kalaaji AN. Role of primary prophylaxis for pneumocystis pneumonia in patients treated with systemic corticosteroids or other immunosuppressive agents for immune-mediated dermatologic conditions. J Am Acad Dermatol 2010 Nov; 63:815.
Comment
The very low risk for PCP is too small to justify routine prophylaxis. In addition to their expense, these medications are frequently associated with adverse effects. The authors sensibly recommend that clinicians avoid routine prophylaxis in patients receiving immunosuppressive agents and that we remain alert to the uncommon possibility of PCP, especially in those with apparent risk factors, which include age >60, concurrent pulmonary disease, leukopenia, hypoalbuminemia, and CD4 counts <300/dL.