THU0358 Hip Joint Avascular Necrosis in A Multi-Ethnic Systemic Lupus Erythematosus Cohort

Background Avascular necrosis of bone (AVN) is a well known complication in patients with systemic lupus erythematosus (SLE). Objectives To determine the prevalence of avascular necrosis (AVN) involving hip joint among SLE patients and its associated factors. Methods Consecutive SLE patients attending outpatient follow-up clinics in National University of Malaysia and Putrajaya Hospital, Malaysia from 2004 until 2014 with confirmed avascular necrosis of hip joint on magnetic resonance imaging (MRI) were reviewed. Demographics and disease characteristics of patients with AVN complications were compared with other lupus controls. Results A total of 300 patients were reviewed and majority of them were Malays (175, 58.3%) followed by Chinese (107, 35.7%), Indian (15, 5%) and others (3, 1%). Eighteen patients (6%) had hip joint AVN and more than two-thirds were bilateral (14 patients, 77.8%). The median onset of AVN was 3 (IQR 4.25) years from diagnosis of lupus. A higher proportion of patients who did not received hydroxychloroquine (HCQ) developed AVN compared to those receiving HCQ (50% vs 24.8%, p=0.02). On the other hand, prednisolone dose ≥60mg daily for at least 2 weeks were associated with a higher prevalence of AVN (55.6% vs 23.4%, p=0.005). Positive antiphospholipid antibody (aPL) was also associated with higher prevalence of AVN (55.6% vs 27%, p=0.01). Multivariable logistic regression analysis revealed that the independent predictors of AVN were prednisolone dose ≥60mg OD [OR 3.7 (95% CI 1.3–9.9)] and aPL positivity [OR3.1 (95% CI 1.1–8.3)]. HCQ use was independently associated with lower prevalence of AVN [OR 0.3 (95% CI 0.1–0.9)]. Conclusions Hip joint AVN was significantly associated with positive aPL, prednisolone dose ≥60mg daily for at least 2 weeks while HCQ use was demonstrated to be associated with lower hip AVN prevalence. References MY Mok et al, Risk factors for avascular necrosis of bone in patients with systemic lupus erythematosus: Is there a role for antiphospholipid antibodies? Ann Rheum Dis 2000;59:462–467 J Lee et al, Osteonecrosis of the hip in Korean patients with systemic lupus erythematosus: risk factors and clinical outcome. Lupus 2014; 23 (1): 39–45. Disclosure of Interest None declared