Avascular necrosis in patients with systemic lupus erythematosus: Prevalence, associations, risk factors and outcome

ObjectivesAvascular necrosis (AVN) is a common complication of Systemic Lupus Erythematosus (SLE) that causes significant morbidity for patients. This study aimed to determine the prevalence of symptomatic AVN in a large SLE cohort and to determine clinical and serological risk factors for symptomatic AVN overall and in early-onset and later-onset AVN subgroups.MethodsPatients with symptomatic AVN (<i>n</i> = 106) and those without AVN (<i>n</i> = 197) were identified in a cohort of 912 patients with SLE and followed up by a standard protocol in this retrospective case control study. Osteonecrosis was recorded when there was radiological evidence. Patients who developed AVN within the first year of SLE diagnosis were compared to those at a later stage as well as all AVN patients to 197 patients without AVN matched for disease duration. SLICC SLE damage index (SDI), and the disease activity (SLEDAI-2K) were determined at AVN diagnosis.ResultsThe prevalence of symptomatic AVN in our SLE cohort (<i>n</i> = 912) was 11.6% (<i>n</i> = 106). The mean age at SLE diagnosis of AVN patients were significantly lower than non-AVN patients (27.6 ± 10.6 vs 32.5 ± 12.6; <i>p</i> = .003). SLE-AVN patients had significantly higher alopecia, photosensitivity, oral ulcers, vasculitic skin rash, artritis, serositis, nephritis, pulmonary hypertension and neurologic involvement than non-AVN SLE patients (<i>p</i> < .05). Compared with the control group, SLE patients with AVN had significantly higher anti-cardiolipin IgG, lupus anticoagulant and anti-phospholipid antibody positivity of any kind (<i>p</i> = .020; 0.020; 0.018, respectively). In 106 patients, AVN was found in a total of 214 joints. Of the patients, 64.2 % (<i>n</i> = 68) had AVN in more than 1 joint. Patients who had AVN ≤1 year after SLE diagnosis had significantly higher mean SLEDAI-2K, higher mean daily steroid dose until diagnosis, and lower age (<i>p</i> = .041; 0.000 and 0.001, respectively). These patients also developed AVN at multiple joints significantly more than other patients (<i>p</i> = .047).ConclusionWe believe that controlling disease activity in the first year of SLE diagnosis and keeping daily steroid dose at minimum levels could be important in preventing early development of debilitating AVN in multiple joints, especially in younger SLE patients.