Does thyroid hormone therapy provide survival benefits in subclinical hypothyroidism?

Use of thyroid hormone therapy does not seem to protect older adults with subclinical hypothyroidism against mortality, but it appears to confer survival benefits to those aged <65 years, results of a study have shown.

This systematic review and meta-analysis sought to summarize the effect of thyroid hormone therapy on mortality in adults with subclinical hypothyroidism.

The investigators searched the databases of PubMed, Embase, Scopus, Web of Science, and Clinicaltrials.gov from inception until 25 April 2020 for studies comparing the effect of thyroid hormone therapy with that of placebo or no therapy in adults with subclinical hypothyroidism on all-cause and cardiovascular mortality.

Two reviewers independently extracted data and assessed study quality. Random-effects models were used for the meta-analyses.

Seven studies (five observational and two randomized controlled trial) comprising 21,055 adults met the inclusion criteria. Overall, thyroid hormone therapy did not significantly correlate with all-cause mortality (pooled relative risk [RR], 0.95, 95 percent confidence interval [CI], 0.75–1.22; p=0.704) or cardiovascular mortality (pooled RR, 0.99, 95 percent CI, 0.82–1.20; p=0.946).

In subgroup analyses, use of thyroid hormone therapy in younger adults (aged <65 years) resulted in a significantly lower all-cause (pooled RR, 0.50, 95 percent CI, 0.29–0.85; p=0.011) and cardiovascular mortality (pooled RR, 0.54, 95 percent CI, 0.37–0.80; p=0.002). However, in older adults (aged ≥65 to 70 years), no association was found between thyroid hormone therapy and mortality.