Epidemiology and risk factors associated with avascular necrosis in patients with autoimmune diseases: a nationwide study

BACKGROUND/AIMS: Avascular necrosis (AVN) is a clinical condition characterized by the death of bone components due to interruption in the blood supply. This study aimed to investigate the epidemiology and determine the risk factors for AVN in patients with autoimmune diseases. METHODS: We conducted a population-based retrospective cohort analysis using claims data from the Taiwan National Health Insurance Research Database. A total of 49,636 patients with autoimmune diseases between January 1, 2005 and December 31, 2013 were included. Cox regression analysis was used to identify associated risk factors for the development of AVN. RESULTS: A total of 490/49,636 patients (1.0%) developed symptomatic AVN. The systemic lupus erythematosus patients had a higher risk of AVN compared to other autoimmune diseases. AVN was positively correlated with male sex (p < 0.001), alcoholism (p < 0.001), mean daily prednisolone dosage 7.51 to 30 mg (p < 0.001) and > 30 mg (p < 0.001), and total cumulative prednisolone dose 0 g to 5 g (p = 0.002). However, AVN was inversely correlated with cumulative duration of hydroxychloroquine exposure > 0.6 years (p < 0.001). CONCLUSIONS: Male sex, systemic lupus erythematosus, alcoholism, mean daily corticosteroid > 7.5 mg and a total cumulative dose of corticosteroid 0 to 5 g were independently associated with the development of AVN in autoimmune patients. While hydroxychloroquine use > 0.6 years conferred significant protection against the development of AVN. Clinicians should regularly assess patients with risk factors to enable the early diagnosis of AVN.