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Heart failure increases hospitalization risk for adults with hypothyroidism
Among adults with hypothyroidism, those with congestive heart failure are more likely and those without are less likely to be hospitalized compared with euthyroid adults, according to findings published in Thyroid.
“Given that hypothyroidism has been associated with various cardiac derangements (ie, impaired cardiac contractility, altered cardiac conduction, increased systemic vascular resistance, dyslipidemia, accelerated atherosclerosis, neurohormonal activation and ventricular remodeling), it has been hypothesized that the relationship between hypothyroidism and adverse outcomes may be dependent on an individual’s underlying cardiac risk,” Kevin Ro, MD, a fellow in the department of endocrinology, diabetes and metabolism at the UCLA David Geffen School of Medicine, and colleagues wrote.
Researchers examined data from a historical cohort study of 52,856 adults who had electronic medical records filed in the UCLA Health System from 1990 to 2015. Participants were categorized as either euthyroid (0.3-4.7 mIU/L) or hypothyroid (> 4.7 mIU/L) based on serum thyroid-stimulating hormone levels.
Of the cohort, 3,065 had hypothyroidism. Diabetes prevalence, thyroid hormone supplementation and the use of antithyroid medications were elevated in this group vs. those without hypothyroidism. Researchers also found that participants in the group were more likely to be women, older in age, white and of Hispanic ethnicity.
During a median follow-up of 5.61 years, there were 13,023 hospitalizations either via inpatient admission or ED visits. Results from those visits indicated that presence of congestive heart failure conferred a higher risk for hospitalization in those with hypothyroidism vs. euthyroid patients (adjusted HR = 1.86; 95% CI, 1.17-2.94). Those with hypothyroidism and no congestive heart failure had a slightly lower risk for hospitalization vs. euthyroid adults (aHR = 0.95; 95% CI, 0.92-0.99). Initial analysis did not find links between hospitalization risk and underlying cardiovascular disease for those with hypothyroidism vs. euthyroid, but sensitivity analysis revealed increased risks — aHR of 3.32 (95% CI, 3.21-3.5) for coronary artery disease and aHR of 1.2 (95% CI, 1.02-1.38) for no CAD, and aHR of 1.98 (CI, 1.79-2.16) for CVD and aHR 0.68 (95% CI, 0.5-0.87) without CVD.
There was a significant link found between age and hospitalization in adults with hypothyroidism, with those younger than 60 years less likely to be hospitalized (HR = 0.89; 95% CI, 0.85-0.94) and those aged 60 years or older more likely to be hospitalized (HR = 1.05; 95% CI, 0.99-1.11) vs. euthyroid adults.
“The findings suggest a decreased risk of hospitalization among those < 60 years old, and hypothyroidism was associated with a significantly decreased risk of hospitalization. It is possible that this observation may be due to the fact that symptoms of hypothyroidism are less pronounced in younger individuals, and thus this group would present to an emergency room less often,” the researchers wrote. “In contrast, we did not observe a differential relationship between hypothyroidism and hospitalization risk on the basis of race or ethnicity in this diverse Southern California-based cohort.”
In total, researchers discovered a 1.9-fold increase in hospitalization risk for those with congestive heart failure in conjunction with hypothyroid. More pronounced risk increases were present for those with CAD and CVD, but hurdles remain in applying these findings to clinical practice, the researchers wrote, specifically noting the need to “determine whether correction of TSH perturbations with thyroid hormone replacement therapy ameliorates hospitalization risk.” – by Phil Neuffer
Disclosures: The authors report no relevant financial disclosures.