Environmental Iodine Content, Female Sex and Age Are Associated with New-Onset Amiodarone-Induced Hypothyroidism: A Systematic Review and Meta-Analysis of Adverse Reactions of Amiodarone on the Thyroid

Abstract

Objectives: To investigate the incidence of new-onset amiodarone-induced hypothyroidism (AIH) and the associated risk factors. Methods: We performed a systematic search in MEDLINE, Embase, the Cochrane Library and the Chinese database from 1995 to 2015. Studies that investigated amiodarone-related adverse reactions on the thyroid were included. A random-effect model was used for the meta-analysis to investigate the incidence rate of AIH and associated risk factors. Results: We identified 465 studies, of which data from 9 studies were included, comprising 1,972 patients. The incidence of AIH was 14.0% (95% confidence interval, CI, 8.7-21.7%) as a whole; it was higher in areas with a high than a low iodine content in the environment (20.3 vs. 8.7%, p < 0.001); subgroup analysis showed that AIH occurred in 19.2% (95% CI 10.2-33.1%) of women and 13.3% (95% CI 7.9-21.7%) of men (p < 0.001). Meta-regression analysis indicated a positive correlation with the mean age and percentage of women. Conclusions: The occurrence of AIH is a relatively frequent complication of amiodarone, and older women are more likely to develop AIH, especially in areas with a high iodine content in the environment, and restriction of total exposure to iodine might decrease the incidence of AIH.