Objective: To investigate risk factors for Pneumocystis carinii pneumonia (PCP) in patients with systemic lupus erythematosus (SLE) and polymyositis/dermatomyositis (PM/DM).
Methods: The subjects were 75 patients hospitalized because of SLE or PM/DM who were administered corticosteroids 40 mg/day or above as prednisolone. The relationship between clinical symptoms of SLE and PM/DM and the occurrence of PCP was evaluated.
Results: Seven patients (9.3%) developed PCP and 3 died. Interstitial pulmonary fibrosis was observed in all 7 patients who developed PCP, and its incidence was significantly higher (p < 0.001) than in those who did not develop PCP (6/68). The incidence of PCP in patients with SLE was 1.7%, but that of patients with PM/DM was 37.5%. The peripheral blood lymphocyte count was 1052.7/microliters in patients who developed PCP, which was significantly lower (p < 0.01) than 1841.6/microliters in patients who did not develop PCP.
Conclusion: A low peripheral lymphocyte count and interstitial pulmonary fibrosis were considered risk factors for PCP in patients administered corticosteroids for SLE or PM/DM.