Association of autoantibody levels with the hazard of autoimmune comorbidities in children with type 1 diabetes

Type 1 diabetes mellitus is an autoimmune disease representing serious burden both on the patients and healthcare systems. Being an autoimmune disease it comes as no surprise that it is often associated with other autoimmune comorbidities, such as coeliac disease or Hashimoto's thyroiditis. As the manifestation of these diseases is often preceded by a longer period of latent ( subclinical) autoimmune process, children diagnosed with type 1 diabetes mellitus are often screened for autoantibodies characteristic for these comorbidities to predict their occurrence. Data from n = 182 children diagnosed with type 1 diabetes mellitus undergoing such screening program were collected from 2007 to 2012. Cox proportional hazards model with time varying covariate was used to model how autoantibody levels are associated with the hazard of the onset of an autoimmune comorbidity. For coeliac disease, only the IgA subclass of anti-transglutaminase autoantibodies turned out to be relevant ( p < 0.0001), with a hazard ratio - for being > 10 U/ml compared to being smaller - of 44.8 ( 95% HR: 11.88-168.8). For Hashimoto's thyroiditis, only anti-thyroid peroxidase autoantibodies were significant ( p < 0.0001), with a hazard ratio raising rapidly to roughly 10 by 100 U/ml, then - after a sharp break in the gradient - raising much more slowly to about 30-40 for the extreme ATPO values greater than 1000 U/ml. This study confirmed the role of autoantibodies in predicting autoimmune comorbidities in T1DM and also demonstrated a way to quantify this effect.