OR06-04 Sociodemographic Differences in Hypothyroidism Disease Control-Measured by "Time-In-Range"

Abstract Disclosure: M. Ettleson: None. N. Thomas: None. M. Ramirez: None. W. Wan: None. D. Hedeker: None. N. Laiteerapong: None. A.C. Bianco: Abbvie. Introduction: The principal goals of hypothyroidism treatment are to resolve symptoms and restore metabolic function while maintaining normal thyroid hormone (TH) levels. Observational studies have identified several clinical factors that are associated with suboptimal TH control. However, most studies are cross-sectional, providing few data on how these factors may affect TH control over time. In this study, we sought to develop and test a “time-in-range” (TIR) parameter to estimate TH control over time. Then, we investigated the impact of sociodemographic factors on TIR. Materials and Methods: We utilized a longitudinal study design of retrospective data collected from levothyroxine (LT4)-treated patients from 2008 - 2023. We applied linear interpolation of thyroid stimulating hormone (TSH) levels to estimate TIR. We used an age-appropriate TSH reference range to determine “in range” status. All included study participants were required to have >2 TSH levels documented over a 2+ year period. TIR was estimated on an annual basis to account for individually varying observation lengths. Clinically relevant outcomes of TIR <75% and <50% were then modeled as a repeated outcome using generalized estimating equations. This allowed for estimations of effect size of age, sex, race, and ethnicity on TIR while adjusting for observation length and comorbidities. Time-above-range (TAR) and time-below-range (TBR) were modeled separately in a similar fashion. Results: A total of 2622 adult patients with LT4-treated hypothyroidism were analyzed, of which 69.9% were female, 51.3% were >65 years of age at baseline, and 24.3% identified as Black. The median length of observation was 3.8 years. The median TIR was 92% and 88% for women and men, respectively (p <0.001). In the adjusted models, male sex and Black race were both associated with an increased likelihood of observing a TIR <50% in a given year (OR 1.30, 95% CI [1.12 – 1.51], p = 0.001; OR 1.36, 95% CI [1.15 – 1.62], p <0.001, respectively). A similar pattern was seen in the TAR >50% model. However, in the TBR >50% model, male sex was protective (OR 0.67, 95% CI [0.53 – 0.84], p <0.001) and Black race did not have a significant effect. Conclusion: In this study, we present a novel approach to measuring TH control in LT4-treated hypothyroidism. Male sex and Black race were associated with worse TH control, but these differences were most prominent in the context of TSH above the normal range. In the future, we aim to investigate TIR as a predictor of adverse health outcomes in hypothyroidism, including cardiovascular events. Presentation: Saturday, July 12, 2025