NEW YORK (Reuters Health) Mar 18 - Pneumocystis jiroveci pneumonia (PCP) is a serious complication in patients with rheumatoid arthritis (RA) who are treated with infliximab (Remicade), according to results of a study published in the March 15th issue of Arthritis and Rheumatism.
"Several clinical trials have demonstrated excellent efficacy for the treatment of RA with infliximab, an anti-tumor necrosis factor-alpha (TNF-alpha) chimeric monoclonal antibody," Dr. Masayoshi Harigai, of Tokyo Medical and Dental University, Japan, and colleagues write. "Because TNF-alpha is one of the key molecules protecting against microorganisms in vivo, treatment with infliximab has been associated with increased risk of opportunistic and serious infections in our cohort."
The researchers compared 21 RA patients receiving infliximab who developed PCP and 102 patients receiving infliximab who did not develop PCP, and identified risk factors for PCP in RA patients treated with infliximab. In the present study, the authors retrospectively reviewed these patients and report detailed clinical, laboratory, and radiographic features.
The median dosages of prednisolone and MTX were 7.5 mg/day and 8 mg/week, respectively, at the onset of PCP. The median length of time between the first infusion of infliximab and PCP onset was 9 weeks. The polymerase chain reaction test detected P. jiroveci in all 19 patients in whom it was conducted.
However, the organism was microscopically identified in only two patients. Computed tomography of the chest in the 21 patients with PCP showed ground-glass opacity either with sharp demarcation by interlobular septa or without interlobular septal boundaries.
Of the 21 patients with PCP, 16 developed acute respiratory failure. All of the patients survived. Serum albumin levels (p < 0.001) and serum IgG levels (p < 0.001) were significantly lower in patients with PCP than in those without PCP.
"The severity of PCP in the present series emphasizes the importance of the clinician's awareness of this opportunistic infection in patients treated for RA with infliximab," Dr. Harigai and colleagues explain. "Early diagnosis and prompt intervention with specific antimicrobial drugs is vital," they note. "The evaluation of risk factors before treatment, as well as careful monitoring of clinical manifestations and laboratory tests, is beneficial for early diagnosis."
Arthritis Rheum 2009;61:305-312.