title: Thyroid dysfunction in chinese patients with chronic hepatitis C treated with interferon alpha: incidence, long-term outcome and predictive factors.
abstract: BACKGROUND
  Thyroid dysfunction (TD) represents an extra-hepatic manifestation of chronic hepatitis C (CHC) and it may also be a side effect of interferon-alpha (IFN-α) based treatment. However, previous studies have shown a wide variation in the incidence of TD in patients with CHC. Furthermore, the long-term outcomes and the predictive factors of TD in patients who receive IFN-α based treatment have still not been fully studied.
  
  
  OBJECTIVE
  The purpose of this study was to describe the incidence and long-term outcomes of TD in Chinese patients with CHC receiving IFN-αbased treatment. We also aimed to identify the predictive factors of TD associated with this type of therapy.
  
  
  METHODS
  A retrospective case-series study of 592 consecutive CHC patients with normal baseline thyroid functions, who received IFN-αbased therapy, was performed. Thyroid function was assessed at baseline and every three months during treatment, as well as in the follow-up after cessation of therapy. The incidence and long-term outcomes of TD were observed. The prevalence of pretreatment thyroid peroxidase antibodies (TPOAb) were assayed in a sex- and age-matched nested case-control study. Multivariable stepwise regression analysis was used to explore the independent effects of the baseline factors, on the incidence of TD.
  
  
  RESULTS
  At the end of the IFN-αbased therapy, 68 patients (11.5%) in the study had developed TD, 58 patients (85.3%) presented with subclinical TD, and only 10 patients (14.7%) developed overt thyroiditis. The thyroid function of 46 patients (67.8%) spontaneously returned to normal in the six months of follow-up and only three patients (4.4%) had persistent overt TD symptoms after the 24 month follow-up period. Multivariate stepwise analysis suggested that gender and pretreatment TPOAb were the independent factors related to the incidence of TD. Both female patients (OR, 4.31; 95%CI, 2.06-7.31; P = 1.26×10-4) and participants with a positive pretreatment TPOAb (OR = 3.9, 95%CI, 1.72-8.54, P = 0.008) had an increased risk for the development of TD.
  
  
  CONCLUSIONS
  The incidence of TD in Chinese patients with CHC during IFN-αbased therapy was 11.5%, the majority of which was subclinical, while only a very small group had long-term overt TD requiring ongoing medical therapy. Female gender and pretreatment TPOAb positivity are risk factors for the development of TD during IFN-αbased therapy.
authors.affiliation: Institute of Infectious Diseases, Southwest Hospital, the Third Military Medical University, Chongqing, China.
authors.forename: Zehui
authors.initials: Z
authors.lastname: Yan
authors.forename: Ke
authors.initials: K
authors.lastname: Fan
authors.forename: Yi
authors.initials: Y
authors.lastname: Fan
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Wang
authors.forename: Qing
authors.initials: Q
authors.lastname: Mao
authors.forename: Guohong
authors.initials: G
authors.lastname: Deng
authors.forename: Yuming
authors.initials: Y
authors.lastname: Wang
keywords: Hepatitis C; Interferon-Alpha