Stan Ursem1, Raymond Noordam2, Jesse van den Berg3, Anita Boelen4, Petra Elders5, Wendy den Elzen6, Annemieke Heijboer7
(1) Amsterdam UMC/Endocrine Laboratory, Amsterdam, the Netherlands. (2) Leiden University Medical Center/Internal Medicine, Leiden, the Netherlands. (3) PHARMO Institute for Drug Outcomes Research, Utrecht, the Netherlands. (4) Amsterdam UMC/Endocrine Laboratory, Amsterdam, the Netherlands. (5) Amsterdam UMC/General Practice Medicine, Amsterdam, the Netherlands. (6) Amsterdam UMC/Laboratory Medicine, Amsterdam, the Netherlands. (7) Amsterdam UMC/Endocrine Laboratory, Amsterdam, the Netherlands.
Background:
Subclinical hyperthyroidism (SHT) has previously been associated with adverse cardiovascular outcomes, yet the magnitude and consistency of risk and its demographic variation remain unclear due to limited sample sizes of subgroups in previous cohorts.
Objectives:
To evaluate the association between SHT and the risk of atherosclerotic complications, atrial fibrillation (AF), heart failure (HF), and all-cause mortality in a large primary care population.
Methods:
This retrospective cohort study analyzed data from the PHARMO Dutch GP database. SHT was Based on thyroid hormone levels available in the dataset. Outcomes were compared between SHT patients (N= 11,163) and a euthyroid reference group (N=46,058) using multivariable Cox regression models.
Results:
SHT was not significantly associated with atherosclerotic complications. However, the risk of AF was markedly increased (multivariate HR 1.4; 95% CI, 1.2–1.6), particularly in patients with TSH <0.1 mU/L and younger patients (aged 30–49 years). HF risk was modestly elevated (multivariate HR 1.2; 95% CI, 1.0–1.4), with a stronger effect in younger patients (aged 30–49 years) and in women. All-cause mortality risk was also higher in the SHT group (multivariate HR 1.5; 95% CI, 1.4–1.6), especially in men and with younger age.
Conclusion:
SHT is associated with increased risks of AF, HF, and all-cause mortality, with some notable demographic differences. Younger patients exhibited a higher relative risk, particularly for AF and all-cause mortality, challenging the traditional focus on older populations. These findings highlight the need for careful monitoring and individualized risk assessment in patients with SHT.