There is no debate that SLE is associated with avascular necrosis, especially active disease. Risk factors seem to include antiphospholipid antibodies, renal disease, and steroid use. There is confounding, however, in that steroids are used in patients with active SLE so it could be due to the steroids, disease or both. In addition, there may be a dose-response where higher-dose steroids may elevate the risk further.
A case control study was performed in SLE patients by Sau Mei Tse et al from Hong Kong (FRI 0393) to determine the incidence and risk factors for AVN in their population. Fifty-five patients with SLE and AVN were compared to 220 without AVN who had SLE.
They found that steroids were the strongest risk factor but that the prevalence of AVN has been decreasing over the last two decades. The only significant univariate variables for AVN risk were Cushiongoid appearance, maximum daily steroid dose, number of major flares, borderline cumulative steroid dose in the first 6 months of treatment, but not antiphospholipid antibodies. They may not have looked for renal disease specifically but it would be included in a major flare. Alcohol was not a risk factor.
Dr. Maeve Gamble did a meta-analysis / systematic literature review for factors associated with AVN in SLE (SAT0407) that included 6 large cohort studies. The prevalence of AVN ranged from 17 to 45% with a mean of 31%. The studies were usually cohorts but still there may have been selection bias. Cumulative steroid dose and disease activity were not significant, whereas renal disease increased the risk two and a half times.
APS and Raynaud's phenomenon were not significantly associated with AVN whereas vasculitis was a risk for AVN. Use of hydroxychloroquine was numerically protective but the result was not significant.
Risk factors for AVN in SLE are difficult to determine in order to modify them and try to prevent AVN.
Dr. Janet Pope is Professor of Medicine at Western University and Division Head of Rheumatology. Dr. Pope's research interests include epidemiologic studies in scleroderma, classification criteria in systemic sclerosis, systemic lupus erythematosus and rheumatoid arthritis.View Full Bio