A meta-analysis of more than 1 million patients and 2 dozen studies has revealed patients over 60 with hypothyroidism were at a 26% greater chance of all-cause mortality.
While previous studies and findings have established a link between hypothyroidism and cardiovascular mortality, new research indicates the condition could also be linked to increased all-cause mortality in older patients.
In what investigators described as the first meta-analysis of its kind, results indicate hypothyroidism was significantly associated with increased all-cause mortality in patients aged 60 and older.
“In accordance with guidelines, our findings imply that individuals with subclinical hypothyroidism--those who have milder thyroid dysfunction--may not benefit from being treated with synthetic thyroid hormone," said Kashif Munir, MD, associate professor in the division of endocrinology, diabetes, and nutrition at the University of Maryland School of Medicine in Baltimore.
To further build on the knowledge of hypothyroidism’s impact on a mortality risk, an international team of investigators conducted a systematic review and meta-analysis of PubMed, Embase, Cochrane Library, Scopus, and Web of Science databases. For the purpose of the current study, databases were queried for the terms “hypothyroidism,” “thyroid,” “aged,” “elder,” “older,” and “mortality.”
Inclusion criteria for studies and articles included examining participants older than 60 years of age, outcome measures had to include all-cause mortality and/or cardiovascular-related mortality with sufficient data to calculate risk estimates, and the studies had to be published as original articles. Case reports, review articles, and editorials were all excluded
The primary outcome of the current analyses was all-cause mortality. Secondary outcomes included cardiovascular mortality, which includes deaths from ischemic heart disease, progressive heart failure, arrhythmia, cardiac arrest, and other diseases of the circulatory system.
In total, investigators identified 13,923 relevant studies through their initial search. After applying inclusion criteria and eliminating duplicate and nonrelevant studies, 27 published articles met all criteria—from these 27, a cohort of 1,114,638 participants was identified for inclusion in the meta-analysis. Investigators noted 15 of the 27 studies were prospective cohort studies and the remaining 12 were retrospective.
Upon analyses, investigators observed patients with hypothyroidism experienced a greater risk of all-cause mortality compared to those with euthyroidism (pooled RR=1.26, 95% CI: 1.15—1.37). Conversely, no significant difference was noted between cardiovascular mortality and patients with hypothyroidism or those with euthyroidism (pooled RR=1.10, 95% CI: 0.84–1.43).
In subgroup analyses, a stronger association was noted with over hypothyroidism and all-cause mortality (pooled RR=1.10, 95% CI: 1.01—1.20) than subclinical hypothyroidism and cardiovascular mortality (pooled RR=1.14, 95% CI: 0.92–1.41). Investigators urged caution when interpreting the results of the meta-analysis due to considerable heterogeneity, which they suggested originated from different study designs and geographic locations included.
"Our analysis found individuals with hypothyroidism aged 60 years or older were 26 percent more likely to die from all causes than individuals in the same age range who did not have the thyroid condition," said investigator Huei-Kai Huang, MD, of Hualien Tzu Chi Hospital and Tzu Chi University in Hualien, Taiwan.
This study, titled “Association of hypothyroidism and mortality in the elderly population: A systematic review and meta-analysis,” was published online in the Endocrine Society's Journal of Clinical Endocrinology & Metabolism.