Original articleAmiodarone-Associated Optic Neuropathy: A Nationwide Study

PurposeTo investigate whether amiodarone use is associated with an increased risk of optic neuropathy.DesignRetrospective population-based cohort study.ParticipantsPatients newly treated with amiodarone between 2005 and 2009 were identified from the Taiwan National Health Insurance Research Database. For each case patient, the study also included 4 age- and gender-matched control subjects who did not receive amiodarone treatment.MethodsCox multivariate regression analysis was used to assess the association between amiodarone and the occurrence of optic neuropathy.Main Outcome MeasuresHazard ratios (HRs) and 95% confidence intervals (CIs).ResultsThe analysis included 6175 amiodarone-treated patients and 24 700 controls. The mean age was 66.7 years and 55.3% of subjects were male. The mean follow-up was 688 days. During the observational period, optic neuropathy developed in 17 amiodarone-treated patients (0.3%) and 30 control patients (0.1%; P = 0.006). Multivariate Cox regression analysis showed that amiodarone-treated patients had a 2-fold increased risk of optic neuropathy (HR, 2.09; 95% CI, 1.13-3.85; P = 0.02). After stratification by gender, amiodarone use remained a significant factor for optic neuropathy development among male subjects (HR, 3.05; 95% CI, 1.42-6.55; P = 0.004), but not among female subjects (HR, 1.15; 95% CI, 0.38-3.47; P = 0.81). Among amiodarone-treated patients, male gender was associated with a nearly 3-fold increased risk of optic neuropathy development compared with female gender (HR, 2.91; 95% CI, 0.94-9.01; P = 0.06). We also detected a trend of increased cumulative incidence of optic neuropathy with longer treatment duration (>41 vs. ≤41 days; HR, 3.46; 95% CI, 0.99-12.07; P = 0.05). However, higher daily dose did not increase the risk of optic neuropathy (HR, 0.96; 95% CI, 0.91-1.00; P = 0.07).ConclusionsThese results demonstrated a higher risk of optic neuropathy in patients treated with amiodarone, especially in males and possibly in patients with longer duration of treatment.