Hypothyroidism as a risk factor for statin intolerance.

Background: Three-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors (statins) are one of the most commonly prescribed classes of medications because of their proven cardiovascular benefits. However, statin intolerance occurs in 5% to 20% of patients. Understanding the basis for statin intolerance remains a key issue in preventive medicine.

Objectives: To evaluate the association of statin intolerance with hypothyroidism in a large integrated health care system, including its sex-specific relationship and subsequent statin rechallenge and prescription history.

Methods: The Intermountain Healthcare electronic medical record database identified patients (n = 2686; males = 1276, females = 1410) with a documentation of intolerance ("allergy") to at least 1 statin. Age and sex similar controls (n = 8103; males = 3892, females = 4211) were identified among patients prescribed statins without documented intolerance. Patients were evaluated for a history of hypothyroidism, development of hypothyroidism, and statin prescription history up to 5 years of follow-up.

Results: A total of 30.2% patients (210 males, 16.5%; 602 females, 42.7%) with statin intolerance had a history of hypothyroidism compared with 21.5% of statin-tolerant patients (475 males, 12.2%; 1266 females, 30.1%), for an odds ratio (OR) in the total population of 1.49 (95% confidence interval [CI] 1.34-1.65; P < .0001); in males, OR was 1.29 (CI 1.07-1.55; P = .001); in females, OR was 1.60 (CI 1.41-1.82; P < .0001). During follow-up, patients with statin intolerance and hypothyroidism were less likely to be on a statin than their statin-intolerant counterparts without hypothyroidism (hazard ratio 0.84; 95% CI 0.75-0.94; P = .002).

Conclusions: Hypothyroidism is more prevalent in those with statin intolerance, both in males and, especially, in females. People with hypothyroidism are less likely to have a prescription for a statin at follow-up than those without hypothyroidism.