Lupus pleuritis: a relevant risk factor for pulmonary tuberculosis

The objective of the study was to evaluate risk factors for pulmonary tuberculosis in systemic lupus erythematosus (SLE). Clinical/laboratorial features of 1283 SLE patients (ACR criteria) followed at the Lupus Clinic were obtained from the electronic register database from 2001 to 2009. Pulmonary tuberculosis was diagnosed in 20 patients (1.6%) (TB+ group). As control group (TB-), 40 patients without tuberculosis matched for age, gender, ethnicity, age at SLE diagnosis, and disease duration were arbitrarily selected. All 20 patients of the TB+ group presented confirmed pulmonary tuberculosis from 1 to 23 years after SLE diagnosis (7.6 ± 8.1 years). Frequencies of previous SLE involvements (cutaneous, articular, hematological, renal, pericarditis, pneumonitis, and central nervous system) were alike in TB+ and TB- groups (p > 0.05). In contrast, prior pleuritis was more frequent in the TB+ group (40% vs. 5%, p = 0.001). In fact, pulmonary tuberculosis was diagnosed in 8/10 patients with previous pleuritis. Immunosuppressive and corticosteroid therapies at the moment of tuberculosis diagnosis were also similar in both groups (p > 0.05). We have identified pleuritis as a relevant risk factor for pulmonary tuberculosis, suggesting that previous pleural injury is a critical part of the complex interplay between altered immune system, socio-economic conditions, and increased susceptibility to this mycobacterial infection.