Liver and thyroid function and autoimmunity during interferon-beta 1b treatment for MS

Background: The occurrence or recurrence of autoimmune diseases or of autoa ntibodies (autoAb) has been reported during type I interferon (IFN) treatme nt. Objective: To define the frequency of thyroid and liver dysfunction and of autoimmunity during IFN-beta 1b (IFNB) treatment of MS. Methods: Prospe ctive 1-year multicenter follow-up of 156 patients with MS recruited by 18 centers was conducted. Thyroid-stimulating hormone and anti-thyroid autoAb were measured by an immunoradiometric method, thyroid hormones by chromatog raphic assay, and non-organ-specific autoAb by indirect immunofluorescence. Tests were repeated every 3 months. The probability of having liver, thyro id, or autoAb alterations was analyzed longitudinally with the generalized estimating equations (GEE) method. Results: Thyroid dysfunction was observe d in 5.3% of cases at baseline and 8.3% de novo during IFNB treatment. GEE analysis showed that the probability of having thyroid alteration did not c hange significantly during treatment compared with baseline. Liver alterati on was observed in 4.6% of cases at baseline and 37.5% de novo during IFNB treatment (p < 0.0001). GEE analysis showed that the probability of having liver alteration was higher (p < 0.002) at months 3 and 6 compared with bas eline, returning to values similar to baseline by month 9. AutoAb were dete cted in 16.1% of patients at baseline and in 20% during IFNB. GEE analysis showed that the probability of having autoAb did not change significantly d uring treatment compared with baseline. Thyroid or liver alteration or auto Ab occurring de novo during IFNB were usually transient. Conclusions: Diffe rently from the frequency of liver function alteration (which significantly increased during the first months of IFNB treatment, suggesting a probable causal relationship with IFNB), the frequency of thyroid dysfunction or of autoimmunity showed random and insignificant changes over time, probably n ot related to IFNB treatment.