Guiding methimazole therapy of autoimmune thyroid disease with thyroid antibody profiles: A predictive and causal inference study

The predictiveness and diagnostic utility of thyroid antibodies-thyroid-stimulating hormone receptor antibody, anti-thyroglobulin antibody and anti-thyroid peroxidase antibody-were investigated in autoimmune thyroid disease. The charts of 85 patients with Hashimoto's thyroiditis or Graves' disease were retrospectively analyzed with causal inference techniques and machine learning algorithms to estimate adjusted associations and interactions among antibodies. The most robust estimated disease diagnosis association was with anti-thyroid peroxidase antibody (mean treatment effect = 0.731) which also gave the best predictive accuracy (area under the receiver operating characteristic curve = 0.875) especially in the middle-aged and older population. Predictive accuracy was enhanced by using several antibodies (area under the curve = 0.913) whereas, interaction effects were trivial. Thyroid-stimulating hormone receptor antibody positivity was highly predictive of the clinical decision to start Methimazole treatment in Graves' disease. The findings suggest that anti-thyroid peroxidase antibody preference for screening and thyroid antibody profile use in treatment planning can guide clinical decision-making, within the constraints of causal inference assumption employed.