Association between giant cell arteritis and thyroid dysfunction in a "real life" population.

PURPOSE: Giant cell arteritis is a systemic autoimmune disorder which involves inflammation of medium to large vessels. The association between giant cell arteritis and autoimmune thyroid disorders has been investigated numerous times in the literature with inconsistent results. Our objective was to evaluate whether a genuine association exists between giant cell arteritis and thyroid dysfunction, which is often due to immune-mediated thyroid disease.
METHODS: Utilizing the medical database of Clalit Health Services, we compared the proportion of hypo and hyperthyroidisim between patients with giant cell arteritis and age-matched and gender-matched controls in a cross-sectional study. Univariate analysis was performed using Chi-square and student t-test and a multivariate analysis was performed using a logistic regression model.
RESULTS: Five thousand six hundred and sixty three giant cell arteritis patients and 23,308 age-matched and gender-matched controls were included in the study. The proportion of hypothyroidism amongst giant cell arteritis patients was increased in comparison with controls (18.2 vs. 6.91%, respectively, p-value < 0.001), as was hyperthyroidism (2.56 and 1.19% respectively, p-value < 0.001). Giant cell arteritis demonstrated an independent association with hypothyroidism on multivariate analysis (Odd Ratios 1.297, 95% Confidence Intervals 1.19-1.42), yet not with hyperthyroidism.
CONCLUSIONS: Giant cell arteritis patients have a higher proportion of hypothyroidism in comparison with matched controls. Physicians treating giant cell arteritis patients should consider screening for thyroid dysfunction on a regular basis.