Endocrine Abstracts

Objectives: Hyperthyroidism affects up to 3% of the population and is associated with arrhythmias, which predispose to myocardial infarction, stroke and pulmonary embolism. Multiple studies indicate that all-cause and cardiovascular mortality are higher in patients with hyperthyroidism compared to the general population. However, associations between treatment modalities for hyperthyroidism and long-term health outcomes remain unclear. This study aims to analyse the literature and establish whether any of these treatments revert the long-term effects of hyperthyroidism.

Methods: Medline and Embase were searched for studies on the effects of different treatments for hyperthyroidism (antithyroid drugs (ATD), radioactive iodine (I-131) and thyroid surgery) on mortality and major adverse cardiovascular events (MACE) in adult patients. References and citations of selected full-text studies were screened. Two reviewers independently assessed eligibility and extracted the data. Bias was assessed with the Ottawa-Newcastle Scale. Outcome data were pooled to compare pairwise hazard rates (HR) using random effects (REML). The study forms part of the network meta-analysis registered in Prospero at the Centre of Reviews and Dissemination (CRD42024524000).

Results: The included studies consisted of large routinely collected cohorts at the national or regional level (Wales, Taiwan, Sweden, Hong Kong, Finland and England), together comprising data on 294,738 patients with average follow-up ranging from 1.5-10.5 years. There was only one study comparing the effects of treatment to the matched background population, showing an increased mortality risk after ATD and I-131 not resolving hyperthyroidism, but not when I-131 induced hypothyroidism within 1 year. When treatment approaches were compared pairwise (5 studies), surgery significantly improved survival when compared with ATD (Hr = 0.43 [95%CI: 0.30-0.62]). The survival after surgery (0.66 [0.41-1.06]) or ATD (0.85 [0.66-1.09]) compared with I-131 therapy was not statistically different. Risk of MACE (4 studies) was increased in all treatment groups when compared to matched controls without hyperthyroidism (ATD: 1.72 [1.23-2.41], I-131: 1.85 [1.17-2.98], surgery: 1.11 [1.03-1.19]). Pairwise comparisons of treatments (3 studies) indicated the highest reduction of MACE risk when surgery was compared to ATD (0.52 [0.25-1.07]), but the effect did not reach statistical significance (P = 0.08). I-131 did not significantly affect MACE risk compared with ATD or surgery (ATD: 0.89 [0.61-1.29], surgery: 0.65 [0.25-1.68]).

Conclusion: Surgery was associated with improved outcomes in mortality and MACE when compared with medical treatment. Current data comparing long-term health consequences following different treatment approaches for hyperthyroidism are sparse. Further studies are needed to support informed decision-making when choosing the optimal therapeutic approach for hyperthyroidism.