Factors associated with anakinra effectiveness and risk of infection in crystal-related flares

OBJECTIVES: To assess the effectiveness and safety of anakinra in crystal-related disease (CRD) flares, and to identify factors associated with treatment failure and risk of infection. METHODS: We conducted a single-centre, retrospective, observational study including adult patients treated with anakinra for a CRD flare between January 2011 and July 2024. Patients were identified in a hospital clinical data warehouse using an electronic query. CRD was confirmed by the presence of crystals in synovial fluid or by characteristic radiological features. Clinical and biological data were collected through medical record review. Treatment effectiveness was assessed retrospectively based on the treating physician's global clinical judgment documented in medical records. Treatment failure was defined as insufficient clinical response requiring treatment escalation or persistent symptoms. Adverse events, including infections, were collected up to one month after anakinra initiation. Factors associated with treatment failure and infection were explored using univariable and multivariable analyses. RESULTS: A total of 292 patients were included. Effectiveness of anakinra was observed in 92.8% of patients after a median treatment duration of 3 days. In multivariate analysis, longer CRD duration (OR 1.11, 95% CI 1.03-1.19) and a history of diabetes (OR 4.00, 95% CI 1.25-14.29) were independently associated with treatment failure. Thirteen patients (4.5%) developed an infection within one month after anakinra initiation, with a median delay of 11 days. No variable was independently associated with infection risk. CONCLUSION: This large real-life study supports the effectiveness and overall safety of anakinra in the management of acute CRD flares.