Background Osteoporosis (OP) and avascular necrosis (AVN) are well-recognized musculoskeletal complications of systemic lupus erythematosus (SLE) and cause significant morbidity. Steroid therapy and the underlying disease process are major contributors to these complications and the degree to which each influences the development of OP and AVN is unclear. Precise rates of AVN and OP are are far higher than that of the general population.
Objectives The aim of this study was to identify the mean prevalence of OP and AVN as well as modifiable risk factors associated with the development of OP and AVN in patients with systemic lupus erythematosus (SLE).
Methods A comprehensive review of both published articles and unpublished abstracts was conducted using the PubMed, EMBASE, and Cochrane databases. All articles relating to risk factors for avascular necrosis and osteoporosis in patients with SLE were included. Exclusion criteria were: osteoporosis in the pediatric population (pediatric patients with AVN were included), publication with 44 or fewer SLE patients, and studies using the same population of patients.
Results Forty-five articles received full review and pediatrics and/or repeat cohorts were excluded; with 10 articles pertaining to avascular necrosis and 13 pertaining to osteoporosis were included. AVN occurred at a rate of 31% (95% CI 17-45%). Modifiable risk factors for AVN were use of steroids, but cumulative dose of steroids was not significant (P=0.18). Antimalarial use was protective but not significantly (OR 0.59; 95% CI 0.3-1.16). SLE disease activity at time of AVN was not significant (P=0.4). Antiphospholipid antibodies and Raynaud's were not associated with AVN but renal involvement (OR 2.4; 95% CI 1.3-4.4, P=0.004) and vasculitis (OR 2.4; 95% CI 1.3-4.7, P=0.008) were. Other risks for AVN in SLE in some studies were: cytotoxic drugs (cyclophosphamide and mycophenolate mofetil), serositis, and anti-Smith antibody.The prevalence of osteoporosis/osteopenia was 55% (95% CI 41-67%). Traditional risks for OP were found in SLE patients with OP (age, cumulative steroid dose) but also SLE damange, and low BMI were frequently reported risk factors for OP. Other risks in some studies included: limited physical activity, premature ovarian failure, decreased vitamin D exposure, decreased osteocalcin, decreased C4 levels, white or non-African Caribbean ethnicity, positive anti-Sm antibody, and negative anti-Ro antibody.
Conclusions Several risk factors for OP and AVN were identified, including steroid use which was associated with both complications. Given that the prevalence of these complications is higher in SLE patients compared with the general population we sought to identify modifiable risk factors. These may be used to identify patients who are at higher risk with the goal to reduce morbidity and ultimately improve quality of life. Renal disease and SLE vasculitis are strongly associated with AVN but from this analysis we could not determine if effective early intervention will decrease the risk. The potential protective effect of antimalarials (though not significant in this review) warrants futher study.
Disclosure of Interest None declared