Background: Subacute thyroiditis (SAT) is a destructive thyroiditis of probable viral origin. Thyroid dysfunction evolves through a set of stages (hyperthyroidism - hypothyroidism - euthyroidism) and is usually temporary, although some patients develop permanent hypothyroidism. The risk factors for permanent hypothyroidism remain largely unclear.
Methods: A retrospective analysis of patients with SAT at the University Hospital of Brussels from 2001-2020 was performed. Firstly, a description of the patient characteristics, inflammatory and thyroid parameters is provided. Secondly, a predictive model for the requirement to initiate thyroid hormone therapy (THT) is developed using logistic regression analysis. The optimal model configuration was selected by forward sequential analysis maximizing the classification accuracy while the prediction performance was validated by leave-one-out cross-validation.
Results: A total of 35 patients were included, with a female predominance (4.8/1). Thyrotoxicosis was detected in the majority of patients (91%), while hypothyroidism developed in 71% (of which 27% were subclinical). THT was initiated in half of the patients (18/35). The discontinuation of THT was attempted in 10/18 patients and was successful in most of these (8/10). The logistic regression model selected the predictors age, season and treatment regimen, and demonstrated a maximum accuracy of 86%, classifying 30 of 35 patients correctly in the outcome measure.
Conclusion: THT was initiated for hypothyroidism in half of the patients, which is more than previously reported, although discontinuation of replacement therapy was successful in most patients in whom attempts were made. A scoring model was developed to identify patients who may benefit from THT in clinical practice.