(CSPOT50) No Elevated Risk of Cataract in Amiodarone Users: A Population-based Active-Comparator Study

Background: Although numerous case reports suggest a potential association between amiodarone and various ophthalmic conditions, no study has directly examined the link between amiodarone and cataracts while considering potential confounders.

Objectives: To assess the potential association between amiodarone use and the subsequent risk of cataract, taking into account potential confounders.

Methods: This study used the cohort design with active comparator new user strategy. We utilized the Longitudinal Health Insurance Database 2005 from the Taiwan National Health Insurance program and involved Taiwanese adults over 40 years old between 2001 and 2013. We identified new users of amiodarone and compared them with new users of propafenone, due to the perceived similar efficacy of propafenone and amiodarone in managing post-surgical supraventricular arrhythmias and in converting recent-onset atrial fibrillation. The primary outcome was the incidence rate of cataract. Inverse-probability treatment-weighting (IPTW) was further used to eliminate the potential confounding effects and Cox proportional-hazard regression analyses were performed to calculate the risk of cataract. Serial subgroup analyses were also performed.

Results: This cohort study included a total of 15,620 patients (42.9% women; average age 64 years). Of these, 12,055 were newly initiated on amiodarone treatment, and 3,565 newly initiated propafenone treatment. In the main analysis, no significant association was found between amiodarone use and cataract risk in either the full cohort (adjusted HR [aHR]: 0.994, 95% CI 0.913 to 1.082) or the IPTW-adjusted cohort (IPTW-aHR: 0.977, 95% CI: 0.900 to 1.060) during the 5-year follow-up. The sensitivity analyses further supported the main findings of this study. Notably, a considerable decrease in cataract risk was observed among heart failure patients (IPTW-aHR: 0.708, 95% CI: 0.554 to 0.905) and over a two-year observation period (IPTW-aHR: 0.889, 95% CI: 0.794 to 0.996), suggesting beneficial effects associated with amiodarone treatment.

Conclusions: Our findings indicate that amiodarone use is not associated with an increased risk of cataracts, after adjusting for various potential confounders. The findings of this study offer important insights for the use of amiodarone in treating arrhythmias, underscore safety considerations for eye care specialists, and aim to enhance patient health. Future studies are encouraged to explore underlying mechanisms and their clinical relevance.