October 30, 2002Open Access
View Full PaperAmiodarone‐induced thyroid dysfunction associated with cumulative dose
Key Result
Amiodarone use was associated with an increased risk of hyperthyroidism (OR 6.3; 95% CI 3.9-10.2) and hypothyroidism (OR 6.6; 95% CI 3.9-11.1) compared to other antiarrhythmics.
Study Design
Type
Case-Control (n=5,522)
Structured PICO
Does amiodarone increase the risk of thyroid disorder compared to other antiarrhythmics in patients starting anti-arrhythmic therapy?
P
Population
5,522 patients with a first prescription for an anti-arrhythmic drug and no previous use of thyroid drugs.
E
Exposure
Amiodarone
C
Comparator
Other antiarrhythmic drugs
O
Outcome
Development of thyroid disorder (defined as starting a thyreomimetic or thyreostatic drug no sooner than 3 months after the start of an anti-arrhythmic drug)safety
Amiodarone significantly increases the risk of both hyperthyroidism and hypothyroidism compared to other antiarrhythmics, with a strong dose-response relationship observed for hyperthyroidism.
Main Result
Odds Ratio: 6.3 (95% CI 3.9–10.2)
Abstract
Abstract Purpose To obtain risk estimates of thyroid disorder in patients starting amiodarone. Methods We followed a cohort of 5522 patients with a first prescription for an anti‐arrhythmic drug and no previous use of thyroid drugs. Within this cohort we conducted a nested case–control analysis. Cases were defined as all patients who started a thyreomimetic or thyreostatic drug no sooner than 3 months after the start of an anti‐arrhythmic drug. Controls were patients with a comparable follow‐up period not receiving any thyroid drugs during the observation period. Results We identified 123 cases who had started thyreostatic drugs and 96 cases who had started a thyreomimetic drug. In users of amiodarone we found an adjusted odds ratio of 6.3 (3.9–10.2) for hyperthyroidism and 6.6 (3.9–11.1) for hypothyroid disease compared to users of other antiarrhythmics. Patients who were exposed to a cumulative dose exceeding 144 g of amiodarone had an adjusted odds ratio of 12.9 (6.1–27.3) for the development of hyperthyroid disease. The dose response for development of hypothyroidism was less pronounced. Conclusions We observed an increased risk for thyroid disorder at the high end of that reported in the literature. The risk of thyroid disorder increased with exposure to higher cumulative doses. Clinicians should keep in mind the possibility of development of thyroid disorders in patients on treatment with amiodarone even after several years of use. Copyright © 2002 John Wiley & Sons, Ltd.