Outcomes in Hospitalized Patients With Subclinical Hypothyroidism

Background This study aimed to investigate the relationship between subclinical hypothyroidism (SCH) and the occurrence of major adverse cardiovascular events (MACE) amongst hospitalized patients. The study further explored the association between SCH and the patients' in-hospital mortality, average length of stay (LOS), and 30-day readmission for all causes.  Methods This was a retrospective, multi-center study. Patients with both thyroid-stimulating hormone (TSH) and free thyroxine (T4) levels available were included and categorized as euthyroid if TSH was 0.36-3.74 mIU/L with normal free T4 and subclinical hypothyroid if TSH was 3.75-9.99 mIU/L with normal free T4. Patients with abnormal free T4 levels, a history of hypothyroidism or hyperthyroidism, and use of any thyroid medications were excluded. Outcomes studied were MACE, in-hospital mortality, hospital LOS, and 30-day readmission for all causes. Results Among the group, 13.4% of the euthyroid group had a MACE event, compared to 14.2% in the SCH group. Mortality rate, 30-day readmission, and average LOS were 3.8%, 20.3%, and 4.80 days in the euthyroid group and 5.9%, 23.2%, and 4.89 days in the SCH group, respectively. Logistic regression models for the outcome MACE did not show statistical significance between the euthyroid and SCH groups. No statistically significant associations were found in secondary outcomes either. Conclusion Our study showed increased MACE, higher mortality, higher 30-day readmission, and prolonged LOS in patients with SCH compared to euthyroid patients. However, the difference was not statistically significant. Our study supports the importance of further prospective studies to better understand the clinical implications of SCH in hospitalized patients and to refine management and treatment strategies.