Prognostic value of acoustic structure quantification in patients with Hashimoto's thyroiditis

Objectives Assessment of thyroid parenchymal echogenicity on ultrasonography is a predictor of future thyroid dysfunction. Our objective was to determine the prognostic value of acoustic structure quantification (ASQ) to predict the outcome of patients with Hashimoto's thyroiditis (HT). Materials and methods We prospectively evaluated 90 patients with HT using ASQ from May to December 2013. Surveillance for the development of overt hypothyroidism was conducted over a median period of 40 months (3-55). ASQ were dichotomized based on optimal cutoff values obtained from ROC curve analysis. The probability of developing overt hypothyroidism was compared between the dichotomized subgroups using Kaplan-Meier analysis and log-rank tests. Multivariate Cox regression analysis was performed to determine significant prognostic factors. Results The cumulative rate of overt hypothyroidism was 67.7%. The median interval to overt hypothyroidism was 27.9 months (95% confidence interval, 12.0-38.0 months). There was no significant difference in the risk of overt hypothyroidism using qualitative echogenicity between groups (p = 0.669) according to Kaplan-Meier analysis. However, the ASQ average (p < 0.001), standard deviation (p = 0.015), and focal disturbance ratio (p < 0.001) were significantly associated with an increased risk of overt hypothyroidism. Multivariate Cox regression analysis revealed that a higher ASQ average (hazard ratio, 1.03; p = 0.03) and higher thyroid-stimulating hormone level (hazard ratio, 1.02; p = 0.02) were independent predictors of overt hypothyroidism. Conclusions ASQ has potential as a prognostic biomarker for predicting the risk of overt hypothyroidism in patients with HT.