QJM Advance Access originally published online on February 26, 2009
QJM 2009 102(5):321-328; doi:10.1093/qjmed/hcp015
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Osteoarticular tuberculosis in patients with systemic lupus erythematosus
From the 1Division of Rheumatology, Department of Medicine, Chris Hani Baragwanath Hospital, University of the Witwatersrand, Johannesburg and 2Epidemiology Centre, School of Public Health, University of the Witwatersrand, Johannesburg, South Africa
Address correspondence to: M. Tikly, Division of Rheumatology, Chris Hani Baragwanath Hospital, PO Bertsham, South Africa. email: tikly.mohammed01{at}gmail.com
Received 4 October 2008 and in revised form 29 January 2009
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Abstract |
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Background: Systemic lupus erythematosus (SLE) patients are at increased risk of developing tuberculosis (TB), particularly extrapulmonary TB (ExP-TB).
Aim: The present study was undertaken to investigate whether SLE patients showed increased susceptibility to develop osteoarticular TB (OA-TB).
Design and Methods: We retrospectively reviewed and compared the frequency of ExP-TB, in particular OA-TB, in patients with SLE at a tertiary hospital in South Africa, to a non-SLE control TB group seen at the same hospital.
Results: TB was diagnosed 111 times in 97 (17%) of the 568 SLE patients. The relative frequency of ExP-TB in the SLE group (25.2%) was significantly lower than in the control group (38.5%) (OR = 1.9, P = 0.006). In contrast, OA-TB was diagnosed in the SLE group in nine (8.1%) patients (seven with peripheral arthritis and two with TB spine) compared to 54 (0.4%) in the overall control group (OR = 20.8, P < 0.001) and 13 (0.2%) in the subgroup of known HIV positive patients in the control group (OR = 44.4, P < 0.001). Within the SLE group, Black ethnicity (P = 0.003), lymphopaenia (P = 0.001), C3/C4 hypocomplementaemia (P = 0.05), corticosteroids [maximum dose (P = 0.002) and duration of treatment (P = 0.02)] and immunosuppressive agents (P = 0.02) were risk factors for TB. Duration of corticosteroid therapy was the only risk factor for OA-TB (P = 0.04).
Conclusion: While the relative frequency of ExP-TB was lower in the SLE group compared to the control group, our findings suggest that SLE patients are at particular risk of developing OA-TB. Further prospective studies are needed to better understand the mechanisms that predispose SLE patients to OA-TB.