Association of hypothyroidism and mortality in the elderly population: A systematic review and meta-analysis

Abstract

Context: The evidence of whether hypothyroidism increases mortality in the elderly populationis currently inconsistent and conflicting.Objective: The objective of this meta-analysis is to determine the impact of hypothyroidism onmortality in the elderly population.Data Sources: PubMed, Embase, Cochrane Library, Scopus, and Web of Science databases weresearched from inception until May 10, 2019.Study Selection: Studies evaluating the association between hypothyroidism and all-cause and/or cardiovascular mortality in the elderly population (ages = 60 years) were eligible.Data Extraction: Two reviewers independently extracted data and assessed the quality of thestudies. Relative risk (RR) was retrieved for synthesis. A random-effects model for meta-analyseswas used.Data Synthesis: A total of 27 cohort studies with 1 114 638 participants met the inclusioncriteria. Overall, patients with hypothyroidism experienced a higher risk of all-cause mortalitythan those with euthyroidism (pooled RR = 1.26, 95% CI: 1.15-1.37); meanwhile, no significantdifference in cardiovascular mortality was found between patients with hypothyroidism andthose with euthyroidism (pooled RR = 1.10, 95% CI: 0.84-1.43). Subgroup analyses revealedthat overt hypothyroidism (pooled RR = 1.10, 95% CI: 1.01-1.20) rather than subclinical hypothyroidism (pooled RR = 1.14, 95% CI: 0.92-1.41) was associated with increased all-causemortality. The heterogeneity primarily originated from different study designs (prospective andretrospective) and geographic locations (Europe, North America, Asia, and Oceania).Conclusions: Based on the current evidence, hypothyroidism is significantly associated withincreased all-cause mortality instead of cardiovascular mortality among the elderly. We observedconsiderable heterogeneity, so caution is needed when interpreting the results. Furtherprospective, large-scale, high-quality studies are warranted to confirm these findings.