Treatment of Hypothyroidism That Contains Liothyronine is Associated With Reduced Risk of Dementia and Mortality
Authors' conclusion
Despite standard LT4 therapy, hypothyroidism remains associated with heightened risks of dementia and mortality. Adding T3 may more effectively mitigate these risks than LT4 alone, but further studies are needed to confirm the cognitive and survival benefits of T3-containing regimens.
Study context
- Population
- Patients with hypothyroidism (on levothyroxine (LT4), LT4 + T3, or desiccated thyroid extract) and controls, TriNetX data1.26 million hypothyroid vs 3.32 million controls
- Exposure
- LT4 + T3 combination therapy vs LT4 monotherapy; hypothyroidism vs controls
- Outcome
- Dementia and mortality, combination vs LT4 monotherapy
- Follow-up
- 20 years
Methodological detailspropensity-score matched, parallel systematic review and meta-analysis of 12 studies
- Propensity-score matched
- Parallel systematic review and meta-analysis of 12 studies
Main finding
As reported in the abstract
Lower dementia risk with combination therapy (RR analysis)
27%
Lower mortality risk with combination therapy (RR analysis)
31%
Reduction in dementia with combination therapy (adjusted Cox model)
16%
Reduction in mortality with combination therapy (adjusted Cox model)
25%
Observational data: associations, not effects.
Further findings
Hypothyroidism vs controls
- Higher dementia risk with hypothyroidism
- ∼1.4-fold
- Increase in mortality with hypothyroidism, even with normal TSH
- >2.0-fold
- Risks most pronounced when TSH off-target
Dementia risk in hypothyroidism (meta-analysis of 12 studies)
- Heightened dementia risk
- 1.4-fold
Original publication
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