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Levothyroxine linked to fewer ischemic heart disease events in younger patients
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The use of levothyroxine to treat subclinical hypothyroidism resulted in a reduced occurrence of ischemic heart disease among young people. However, the association was not reported in older patients.
According to researchers, these findings should be confirmed in a prospective, randomized controlled trial.
Those with new subclinical hypothyroidism were identified (3,093 younger patients and 1,642 older patients) using the United Kingdom General Practitioner Research Database, a large primary care database of more than 10 million patients. Patient data were recorded in 2001, and outcomes were examined until March 2009.
Separate analyses were performed for younger (aged 40 to 70 years) and older (.70 years) patients, and after adjusting for conventional ischemic heart disease risk factors, baseline serum thyrotropin levels and initiation of levothyroxine treatment as a time-dependent covariate, HRs for fatal and nonfatal events were calculated.
Levothyroxine was used to treat 52.8% of younger patients and 49.9% of older patients during a median follow-up period of 7.6 years.
Among 1,634 younger patients treated with levothyroxine, 68 incident ischemic heart disease events occurred, compared with 97 events in 1,459 untreated patients (HR=0.61; 95% CI, 0.39-0.95). Among older patients, however, 104 events occurred among 819 treated patients vs. 88 events in 823 untreated patients (HR=0.99; 95% CI, 0.59-1.33).
According to the researchers, recent meta-analyses have confirmed an association between subclinical hypothyroidism and increased cardiovascular events and mortality, especially in young to middle-aged adults. These epidemiologic associations do not, however, prove that treating subclinical hypothyroidism would be effective, they wrote.
“Thus, only adequately powered randomized controlled intervention trials will be able to demonstrate whether treatment of [subclinical hypothyroidism] is worthwhile in terms of improvement in both cardiovascular disease risk and symptoms. However, such a trial has not been performed to date, and no such trials are ongoing.”
Disclosure: Simon H.S. Pearce, MD, reports receiving speakers’ fees from Merck Serono.
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