Adults with hypothyroidism and high TSH have increased risk for hospital readmission
Inpatients who are undertreated for hypothyroidism are more likely to be hospitalized longer and have a higher risk for readmission than those with normal thyroid-stimulating hormone levels, according to study findings.
“For any patient with hypothyroidism, a TSH level greater than 10 mIU/L portends not only poor long-term outcomes — increased risk of cardiovascular morbidity and mortality — but also worse hospital outcomes, which I would classify as a short-term outcome,” Matthew Ettleson, MD, clinical fellow at the University of Chicago, told Healio. “I don’t believe this is how most clinicians think about the treatment of hypothyroidism, but periods of undertreatment can put patients at risk of worse outcomes when other medical or surgical conditions require hospitalization.”
Ettleson and colleagues conducted a retrospective cohort study of hospital outcomes for adults with and without hypothyroidism. Data were collected from the IBM MarketScan Commercial Claims and Encounters Database from 2008 to 2015. Adults aged 18 to 64 years with at least one TSH measurement and a surgical or medical hospital admission in the same year were included. Participants were categorized as having hypothyroidism if they had at least one prescription claim for levothyroxine prior to admission during the same calendar year, a prehospitalization TSH value of greater than 10 mIU/L, or a diagnosis of hypothyroidism at hospital admissiom. Adults with hypothyroidism were split into four subgroups based on prehospitalization TSH level, with low TSH categorized as less than 0.4 mIU/L, normal TSH between 0.4 mIU/L and 4.5 mIU/L, intermediate TSH between 4.51 mIU/L and 10 mIU/L, and high TSH greater than 10 mIU/L. Length of hospitalization, in-hospital mortality, and 30-day and 90-day readmission rates were the primary outcomes. All TSH values were collected at least 7 days prior to admission.
The findings were published in The Journal of Clinical Endocrinology & Metabolism.
High TSH increases risk for poor hospital outcomes
Of the 43,478 adults in the study cohort, 8,873 had hypothyroidism. Of those with hypothyroidism, 53.8% had a prescription claim for levothyroxine and a hypothyroidism diagnosis associated with admission, 23.7% had a levothyroxine prescription only and 21.8% had a hypothyroidism diagnosis alone.
Hospital outcomes differed by TSH level. No differences in any hospital outcomes were observed in the low TSH and intermediate TSH subgroups. Those with hypothyroidism and normal TSH had a lower rate of in-hospital mortality (0.3% vs. 0.6%; P = .004) and a lower 90-day readmission rate (12.6% vs. 13.7%; P = .004) compared with controls without hypothyroidism. Adults with hypothyroidism and high TSH had a longer mean length of hospitalization (4.4 days vs. 3.7 days; P = .005), a higher 30-day readmission rate (13.3% vs. 9%; P < .001) and a higher 90-day readmission rate (22.1% vs. 15.7%; P < .001) compared with controls.
In multivariate analysis, adults with hypothyroidism and normal TSH had a lower risk for in-hospital mortality (RR = 0.46; 95% CI, 0.27-0.79; P = .004) and a lower risk for readmission at 90 days (RR = 0.92; 95% CI, 0.85-0.99; P = .02) compared with controls. Those with hypothyroidism and high TSH had a higher risk for both 30-day readmission (RR = 1.49; 95% CI, 1.2-1.85; P < .001) and 90-day readmission (RR = 1.43; 95% CI, 1.21-1.67; P < .001) compared with controls.
More research needed
“The study reflects the importance of maintaining optimal thyroid hormone replacement in patients with hypothyroidism,” Ettleson said. “Millions of people in the U.S. are treated for hypothyroidism, and up to one-third of those patients at any given time may be undertreated or overtreated. Minimizing the amount of time patients are undertreated with thyroid hormone, especially prior to a planned hospital admission, could decrease hospital length of stay and readmission rates for a large number of patients each year.”
Ettleson said more research is needed to explore the role of hypothyroidism as a comorbidity for hospitalized adults, including whether adults who were undertreated prior to admission should receive a higher-than-baseline dose of thyroid hormone to improve outcomes during hospitalization and whether TSH should be routinely checked before surgery in those with hypothyroidism.
For more information:
Matthew Ettleson, MD, can be reached at matthew.ettleson@uchospitals.edu.
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