Association between Uterine Fibroid and Benign Thyroid Disease: Nationwide Population-Based Cohort Study

Abstract

Background Uterine fibroid and benign thyroid disease are common diseases in women. Objective This study aims to evaluate both diseases are related. Study Design: We established the uterine fibroid group according to diagnosis codes and surgery codes using the Korea National Health Insurance data from 2007 to 2020. All women from 20 to 50 years old with uterine myomectomy from 2007 to 2020 were identified (uterine fibroids group). For controls, 1:1 propensity score matching was performed on age at 5-year intervals, socio-economic status (SES), region, Charlson comorbidity index (CCI), and menopause (control group). Thyroid disease cases were selected using the thyroid disease diagnosis code and thyroid-associated laboratory examination. Results A total of 21,246 patients were extracted from the uterine fibroid and control groups, respectively. The median ages of each group were 40 (range, 35 ~ 44) years and 40 (range, 35 ~ 44) years old. Benign thyroid disease was 469 (2.2%) in the uterine fibroid group and 246 (1.2%) in the control group. Among benign thyroid diseases, hypothyroidism was the largest in both groups. A non-toxic single thyroid nodule followed it. The uterine fibroid group had a higher incidence of hypothyroidism {relative risk (RR) 1.943, 95% CI 1.5-2.516), autoimmune thyroid disease (RR 1.59, 95% CI 1.065–2.373), goiter (RR 1.773, 95% CI 1.051–2.99), nontoxic single thyroid nodule (RR 2.213, 95% CI 1.685–2.907), other thyroid disease (RR 2.31, 95% CI 1.608–3.317), and total thyroid disease (RR 1.905, 95% CI 1.63–2.226) in logistic regression analysis adjusted for age, SES, region, CCI, and menopause compared than the control group. The uterine fibroid group had a higher risk of hypothyroidism (HR 1.431, 95% CI 1.023–2.001) and nontoxic single thyroid nodule (HR 1.511, 95% CI) in cox regression adjusted for age, SES, region, CCI, and menopause. Conclusions Uterine fibroid might be associated with hypothyroidism and thyroid nodule.