[Clinical characteristics and risk factors in 118 patients with systemic lupus erythematosus and osteonecrosis]

Objective: To investigate the clinical characteristics and risk factors for osteonecrosis (ON) in patients with systemic lupus erythematosus (SLE). Methods: This is a case-control study. A total of 118 patients diagnosed with SLE complicated with ON (study group) were retrospectively analyzed between 2014 and 2019. Gender, age, and course matched 118 SLE patients without ON were selected as controls. Clinical manifestations, laboratory findings, medical history, and treatments were recorded and analyzed. Results: Among 118 patients, the male to female ratio was 20 to 98 with a median age of 27 years and course of disease 1-168 months. Compared with the control group, the study group presented a longer cumulative duration of glucocorticoid therapy [36.5 (0-168) months vs. 19.0(0-168) months on average, P<0.05], a higher incidence of osteoporosis (29.7% vs. 4.2%, P<0.001), a higher frequency of immune-suppressive therapy (83.9% vs. 64.4%, P=0.035), more organs involveed [median 2 (0-5) vs. 1 (0-4)], and a higher SLE disease activity index (SLEDAI) (14.22±7.40 vs. 11.63±6.11, P<0.05) in univariate logistic regression. The control group had a higher rate of positive Coombs test (39.8% vs. 7.6%, P<0.05). No statistical difference on methylprednisolone (MP) pulse therapy (P>0.05) was observed. Multivariate logistic regression suggested that SLEDAI (OR= 1.070, 95%CI 1.026-1.116, P<0.005), osteoporosis (OR=10.668, 95%CI 3.911-29.103, P<0.001) and a positive Coombs test(OR=0.492, 95%CI 0.266-0.910, P<0.05) were related to the development of ON in SLE patients. Conclusion: A higher disease activity and the presence of osteoporosis are associated with an increased risk of ON in patients with SLE, and positive Coombs test seems a protective factor of ON.