High Thyrotropin Levels and Risk of Mortality in the Elderly With Subclinical Hypothyroidism: A Systematic Review and Meta-analysis

ObjectiveThis study aims to determine whether elevated endogenous thyrotropin levels contribute to an increased risk of adverse outcomes, such as all-cause mortality in older adults with subclinical hypothyroidism.MethodsEight electronic databases were searched for relevant articles from inception until March 23, 2022. Cohort studies assessing the association between thyrotropin levels and the risk of mortality among older adults aged ≥60 years with subclinical hypothyroidism were eligible. The outcomes of interest were either all-cause or cardiovascular-related mortality. Two independent researchers assessed the eligibility of the studies and collected data through a previously defined data extraction form. The Newcastle-Ottawa Scale was used to evaluate the quality of evidence, and multivariate-adjusted hazard ratios (HRs) (95% Cl) were collected as the necessary risk estimate for synthesis. Random-effects models were applied for meta-analysis.ResultsOverall, 13 studies involving 44 514 participants were included in this meta-analysis. There were no significant differences in the risk of all-cause mortality (pooled HR: 1.18 [95% Cl: 0.95, 1.45], I² = 94%) and cardiovascular-related mortality (pooled HR: 1.08 [95% Cl: 0.94, 1.23], I² = 0%) between euthyroid older adults and older adults with subclinical hypothyroidism. The results remained the same when only older adults with thyrotropin ≥10 mIU/L were assessed (pooled HR for all-cause mortality and cardiovascular-related mortality, respectively: 1.53 [95% Cl: 0.81, 2.88], I² = 22%, 1.35 [95% Cl: 0.63, 2.86], I² = 43%).ConclusionHigh thyrotropin levels are not associated with increased risk for all-cause mortality as well as cardiovascular-related mortality in older adults aged ≥60 years with subclinical hypothyroidism, suggesting an unnecessity in initialing treatment.