Objective: Assess the risk of incident gout following exposure to recombinant zoster vaccine (RZV).
Methods: This case-only, self-controlled risk interval study included a cohort of US fee-for-service Medicare (Part A, B, and D) beneficiaries aged ≥65 years. The exposure was receipt of at least one dose of the two-dose RZV regimen in 2018 or 2019. The risk and control windows were days 1-30 and days 31-60, respectively, following vaccination. Incident gout was defined as the first episode of gout during the risk or control window, with no evidence of gout in the last 365 days. We estimated the relative risk (RR) and 95 % confidence interval (CI) of incident gout in the risk window relative to the control window, using conditional Poisson regression models. Sensitivity analyses included a dose-compliant subanalysis of individuals who received dose 2 60-183 days after dose 1; dose-specific analysis; seasonality adjustment; and COVID-19 adjustment for potential detection bias due to the pandemic.
Results: The 1290 RZV-exposed individuals with incident gout were primarily White (86.98 %), male (61.16 %), and aged 70-79 years (55.82 %). The RR of incident gout was 1.00 (95 % CI 0.90, 1.12). In the dose-compliant sensitivity analysis (n = 959 cases of incident gout), the RR of incident gout was 0.99 (95 % CI 0.87, 1.13). The findings were unchanged in the dose-specific, seasonality, and COVID-19 sensitivity analyses.
Conclusion: The findings suggest that RZV is not significantly associated with an increased risk of incident gout in the Medicare population aged ≥65 years.
Keywords: Arthritis; Infections; Inflammation; Observational study; Vaccine; Viruses.
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