Suboptimal Thyroid Hormone Replacement Is Associated With Worse Hospital Outcomes

Abstract

Abstract Context Many patients with hypothyroidism receive suboptimal treatment that may affect hospital outcomes. Objective This work aimed to identify differences in hospital outcomes between patients with and without hypothyroidism. Methods A retrospective cohort study, using the propensity score-based fine stratification method to balance covariates, was conducted using a large, US-based, commercial claims database from January 1, 2008 to December 31, 2015. Participants included patients aged 64 years and younger who had a thyrotropin (TSH) level collected before a hospital admission. Covariates included age, sex, US region, type of admission, year of admission, and comorbidities. Exposure included clinical hypothyroidism, which was divided into 4 subgroups based on prehospitalization TSH level: low (TSH < 0.40 mIU/L), normal (TSH 0.40-4.50 mIU/L), intermediate (TSH 4.51-10.00 mIU/L), and high (TSH > 10.00 mIU/L). Main outcome measures included length of stay (LOS), in-hospital mortality, and readmission outcomes. Results A total of 43 478 patients were included in the final study population, of whom 8873 had a diagnosis of hypothyroidism. Those with a high prehospitalization TSH level had an LOS that was 1.2 days longer (95% CI, 1.1-1.3; P = .003), a 49% higher risk of 30-day readmission (relative risk [RR] 1.49; 95% CI, 1.20-1.85; P < .001), and a 43% higher rate of 90-day readmission (RR 1.43; 95% CI, 1.21-1.67; P < .001) compared to balanced controls. Patients with normal TSH levels exhibited decreased risk of in-hospital mortality (RR 0.46; 95% CI, 0.27-0.79; P = .004) and 90-day readmission (RR 0.92; 95% CI, 0.85-0.99; P = .02). Conclusion The results suggest suboptimal treatment of hypothyroidism is associated with worse hospital outcomes, including longer LOS and higher rate of readmission.