Thyroidectomy, Radioactive Iodine Could Prevent More CV Events than Antithyroid Drugs

Elizabeth Pearce, MD, MSc
Credit: Boston Medical Center

Opting for thyroidectomy or radioactive iodine therapy could be a better way to stave off the long-term cardiovascular risk among patients with hyperthyroidism rather than choosing medical management, according to a new study.

An analysis of more than 100,000 patients with newly diagnosed hyperthyroidism, results of the study suggest patients treated with radioactive iodine experienced a lower risk of major adverse cardiovascular events and patients treated with surgery had a reduced risk of events and mortality relative to their counterparts receiving antithyroid drugs.¹

“While there are three main treatment options for this condition, the selection of therapy needs to be individualized – this is not one-size-fits-all,” said study investigator Elizabeth Pearce, MD, MSc, professor of Medicine at the Boston University School of Medicine.² “Our study suggests that it may be important to consider an individual's cardiovascular risk in making decisions about hyperthyroidism treatment.”

For patients with hyperthyroidism, the community has identified 3 treatment approaches with long-term benefit in the form of antithyroid drugs, radioactive iodine therapy, and thyroidectomy. Despite being staples in management of care of these patients, few research endeavors have compared long-term benefits and risks of the 3 modalities as it pertains to risk of major adverse cardiovascular events and all-cause mortality.

With this in mind, Pearce and a team of colleagues designed the current study to estimate these risks among patients with newly diagnosed hyperthyroidism within the Taiwan National Health Insurance Research Database. A database encompassing Taiwan’s entire 23.6-million-person population, investigators obtained data from a cohort of 114,062 patients aged 20 years or older with newly diagnosed hyperthyroidism between 2011 and 2020 for inclusion in their analyses.¹

The primary outcomes of interest for the study were major adverse cardiovascular events and all-cause mortality. Investigators defined major adverse cardiovascular events as a composite of acute myocardial infarction, stroke, heart failure, and cardiovascular mortality.¹

For the purpose of analysis, treatment groups were determined within 18 months of diagnosis, with follow-up continuing until development of a major adverse cardiovascular event,all-cause mortality, or the end date of the database. Of note, the antithyroid drug group received antithyroid drugs only while the radioactive iodine and surgery groups could receive antithyroid drugs prior to treatment. Investigators pointed out any patients who underwent who underwent thyroid surgery without RAI was classified into the surgery group and vice versa.¹

The 114,062-person cohort identified for inclusion had a mean age of 44.1 (Standard deviation [SD], 13.6) years, 73.2% were female, and the mean follow-up duration was 4.4 (SD, 2.5) years. Among the overall study cohort, 93.9% received antithyroid drugs, 1.1% received radioactive iodine, and 5.1% underwent thyroid surgery. Among the cohort who underwent surgery, 17.7% had a total thyroidectomy, 37.5% had a near-total thyroidectomy, 25.6% had a lobectomy, 16.5% had a bilateral subtotal thyroidectomy, and 2.7% had a unilateral subtotal thyroidectomy.¹

Upon analysis, results indicated patients receiving radioactive iodine (Hazard Ratio [HR], 0.45; 95% Confidence Interval [CI], 0.22-0.93; P = .03) or who and had undergone surgery (HR, 0.76; 9% CI, 0.59-0.98; P =.04). Further analysis revealed those who underwent surgery had significantly lower risks than those in the antithyroid drug group for heart failure (HR, 0.33; 95% CI, 0.18-0.59; P < .001), cardiovascular mortality (HR, 0.45; 95% CI, 0.26-0.79; P = .005), and all-cause mortality (HR , 0.53; 95% CI, 0.41-0.68; P < .001).¹

When assessing outcomes according to patient sex, results indicated female patients treated with surgery had significantly lower risks of heart failure (HR = 0.33; 95% CI, 0.18-0.61; P < .001), cardiovascular mortality (HR, 0.41; 95% CI, 0.19-0.86; P = .02), and all-cause mortality (HR, 0.54; 95% CI, 0.40-0.72; P < .001) compared to their counterparts treated with antithyroid drugs. Among male patients, surgery was associated with a reduction in the risk of all-cause mortality relative to treatment with antithyroid drugs (HR, 0.50; 95% CI, 0.31-0.81; P=.005).¹

Investigators called attention to multiple limitations within their study to consider when interpreting results. These included but were not limited to reliance on ICD codes, the retrospective nature of the cohort, and lack of granular clinical information, such as lifestyle habits, smoking status, and body mass index.¹

“These findings should be interpreted with caution owing to the retrospective, observational nature of the study design, which precludes the evaluation of causal relationships,” wrote investigators.¹ “Further large, long-term prospective studies or randomized clinical trials comparing treatment modalities are needed to provide evidence to support patient-centered decision-making.”

References:

1. _{^{Peng CC, Lin Y, Lee SY, et al. MACE and Hyperthyroidism Treated With Medication, Radioactive Iodine, or Thyroidectomy. JAMA Netw Open. 2024;7(3):e240904. doi:10.1001/jamanetworkopen.2024.0904}}
2. _{^{BU Medicine. Lower risk of death, major adverse cardiovascular events in hyperthyroid patients treated with surgery than with medication. EurekAlert! March 4, 2024. Accessed March 5, 2024. https://www.eurekalert.org/news-releases/1036438.}}