Thyroid function and autoimmunity during interferon,beta-1b treatment: A multicenter prospective study

Thyroid dysfunction and autoimmunity have been reported during type I inter feron therapy, namely interferon-a for chronic hepatitis or interferon-P fo r multiple sclerosis. To define the frequency of thyroid dysfunction and au toimmunity during interferon-beta treatment, 156 multiple sclerosis patient s were prospectively followed up by 18 centers for 1 yr after starting inte rferon-beta -1b treatment. Serial clinical assessments and tests of thyroid and liver function and antithyroid autoantibodies (all performed by the sa me centralized laboratory) were conducted every 3 months. TSH and antithyro id autoantibodies against human TG or thyroid microsomal antigens were meas ured by immunoradiometric methods; free T-3 and T-4 were measured by chroma tographic assays. Longitudinal occurrence of thyroid or liver alterations o r of autoantibodies was analyzed with the generalized estimating equations method, correcting for the correlation of repeated measurements of the same subject over time. Pretreatment comparison with a control group of 437 hea lthy blood donors did not show significant differences in the frequency of thyroid dysfunction or antithyroid autoantibody positivity. During interfer on-beta treatment, the de novo frequency of thyroid alteration was 8.3%, th at of liver alteration was 37.5%, and that of antithyroid autoantibody was 4.5%. Generalized estimating equations analysis demonstrated that the frequ ency of alteration significantly increased during treatment compared with t he baseline value (odds ratio, 7.03; confidence interval, 2.49-19.9), where as that of thyroid alteration or antithyroid autoantibodies did not. The fr equency of thyroid dysfunction during interferon-beta treatment showed rand om, nonsignificant changes over time and, in addition, was not correlated t o antithyroid autoantibody positivity.