Prevalence and risk factors of osteonecrosis of the femoral head in patients with ANCA-associated vasculitis: a multicentre cohort study

ObjectiveWe aimed to determine the prevalence and risk factors for osteonecrosis of the femoral head (ONFH) in a multicentre cohort of patients with antineutrophil cytoplasmic antibody-associated vasculitis (AAV).MethodsOne hundred and eighty-six AAV patients who underwent radiographs and MRI screening of bilateral hip joints at more than 6 months after initial remission induction therapy (RIT) were retrospectively assessed for the presence of ONFH.ResultsAmong 186 AAV patients, 33 (18%) were diagnosed with ONFH. Among the patients with ONFH, 55% were asymptomatic and 64% had bilateral ONFH. Seventy-six per cent of ONFH joints were in precollapse stages (stage <= 2), whereas 24% of ONFH joints were in collapse stages (stage >= 3). Moreover, 56% of the precollapse stage joints were already at risk of future collapse (type >= C-1). Even in asymptomatic ONFH patients, 39% of the precollapse stage joints were type >= C-1. Prednisolone dose of >= 20 mg/day on day 90 of RIT was an independent risk factor for ONFH in AAV patients (OR 1.072, 95% CI 1.017 to 1.130, p=0.009). Rituximab use was a significant beneficial factor against ONFH (p=0.019), but the multivariate analysis rejected its significance (p=0.257).ConclusionEighteen per cent of AAV patients developed ONFH, and two-thirds of the ONFH joints were already in collapse stages or at risk of future collapse. Prednisolone dose of >= 20 mg/day on day 90 of RIT was an independent risk factor for ONFH. A rapid reduction of glucocorticoids in RIT and early detection of precollapse ONFH by MRI may decrease and intervene ONFH development in AAV patients.

Automated summary

Objective: To determine the prevalence and risk factors for osteonecrosis of the femoral head (ONFH) in AAV patients. Methods: Assessment of 186 AAV patients for the presence of ONFH through radiographs and MRI screening. Results: 18% of AAV patients were diagnosed with ONFH, and 64% of them had bilateral ONFH. Prednisolone dose of >= 20 mg/day on day 90 of RIT was identified as an independent risk factor for ONFH. Conclusion: Early detection of precollapse ONFH by MRI and rapid reduction of glucocorticoids in RIT may help prevent the development of ONFH in AAV patients.