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Levothyroxine does not increase mortality risk in hypothyroidism, CVD
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In patients with subclinical hypothyroidism and cardiovascular disease, levothyroxine therapy does not increase the risk for all-cause mortality, a major adverse cardiac event or hospital admission.
Mette Nygaard Andersen, MD, of the department of cardiology, Gentofte University Hospital in Hellerup, Denmark, and colleagues evaluated data on 61,611 adults (63.8% women; mean age, 73.6 years) from three distinct regions in Denmark who underwent a thyroid function test between 1997-2011. Researchers sought to determine the effects of levothyroxine treatment in patients with both subclinical hypothyroidism and heart disease. Participants were included in the study if they had a previous diagnosis of CVD and a first-time thyroid function test. Follow-up was conducted for a median 5.6 years.
Overall 1,192 participants were diagnosed with subclinical hypothyroidism; 975 with mild subclinical hypothyroidism (thyroid-stimulating hormone between 5-10 mIU/L) and 217 with severe subclinical hypothyroidism (TSH > 10 mIU/L). A prescription for levothyroxine was claimed by 136 participants for a median treatment time of 1,306 days and a mean daily dose of 76.6 µg.
Through follow-up there were 694 deaths, 585 major adverse cardiac events and 1,064 hospital admissions.
Compared with participants not treated with levothyroxine, participants treated with levothyroxine did not demonstrate a significantly increased risk for all-cause mortality (adjusted incidence rate ratio [IRR] = 1.17; 95% CI, 0.9-1.52), major adverse cardiac event (adjusted IRR = 1.08; 95% CI, 0.8-1.45) or hospital admission (adjusted IRR = 0.94; 95% CI, 0.71-1.24).
“Levothyroxine treatment in patients with subclinical hypothyroidism and concomitant heart disease seems not associated with a significant change in the risk of all-cause mortality, [major adverse cardiac events] or hospital admission in a real-world cohort study,” the researchers wrote. “Our findings support the idea that decisions regarding levothyroxine treatment in subclinical hypothyroidism patients with concomitant heart disease should be patient-based, as treatment may have other health benefits, such as change in cholesterol levels, symptom relief, weight loss or quality of life in general, which in itself can be of significant importance for the patient.” – by Amber Cox
Disclosure: The researchers report no relevant financial disclosures.
Perspective
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Kenneth D. Burman
Andersen and colleagues performed an excellent retrospective study assessing whether levothyroxine treatment of cardiac patients with subclinical hypothyroidism altered all-cause mortality, major adverse cardiac events (MACE) or all-cause hospital admissions over a median of 5.6 years follow-up. The results indicated that levothyroxine treatment did not statistically significantly influence these parameters compared to subclinical hypothyroid patients not treated with levothyroxine. As noted by the authors, there are several limitations to this study including lack of information regarding cardiac indices and cardiac risk factors, and limited information regarding levothyroxine compliance and frequency of thyroid function tests. This study adds to our understanding in this area but studies prospective in nature are indicated that also examine specific cardiac parameters (eg, EKG, cardiac echograms, cardiac monitoring for arrhythmias, MACE, mortality) and monitor thyroid function tests closely. The issue of whether subclinical hypothyroidism contributes to cardiac disease is important.
Disclosure:Burman reports no relevant financial disclosures.
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