Association between Hashimoto's thyroiditis and cholelithiasis: a retrospective cohort study in Taiwan

Objective To investigate the relation of Hashimoto's thyroiditis (HT) to cholelithiasis and cholecystectomy in a retrospective population-based study. Setting Cohort study. Participants We identified 1268 patients aged 20 years with HT between 2000 and 2010 as the study cohort. Primary and secondary outcome measures Patients without HT were randomly selected from a database and propensity-matched with the study cohort at a 1:4 ratio according to age, sex, comorbidities and year of the index date to measure the incidence of cholelithiasis and cholecystectomy. Results The cumulative incidence of cholelithiasis was higher in the HT cohort than that in the non-HT cohort (log-rank test, p<0.001), with a 1.91-fold higher risk of choleithiasis (95% CI 1.58 to 2.33) after adjustment for comorbidities. The age-specific relative risk of cholelithiasis in the HT cohort was higher than that in the non-HT cohort for patients aged 50 years (adjusted HR (aHR)=2.59, 95%CI 1.33 to 5.03). The sex-specific relative risk of cholelithiasis in the HT cohort was higher than that in the non-HT cohort for women (aHR=1.99, 95%CI 1.63 to 2.44). Compared with those in the non-HT cohort, patients with HT without (aHR=1.95, 95%CI 1.53 to 2.49) and with (aHR=1.94, 95%CI 1.51 to 2.49) thyroxine treatment were associated with a higher risk of cholelithiasis. Compared with those in the non-HT cohort, patients with HT had a higher risk of cholecystectomy (aHR=1.28, 95%CI 1.02 to 1.61). Conclusions Inability to obtain information on several potential confounding factors and misclassification of important covariates are the major limitations of the study. Our study indicates HT per se was associated with the development of cholelithiasis, which has been validated by the association between cholecystectomy and HT. Surveys and health education on cholelithiasis in women aged 50 years with HT should be considered by clinicians, and further prospective research should be done on this topic.