Searchable abstracts of presentations at key conferences in endocrinology
Endocrine Abstracts (2016) 41 GP211 | DOI: 10.1530/endoabs.41.GP211

1Department of Cardiology, Gentofte University Hospital, Hellerup, Denmark; 2Elective Laboratory of the Capitol Region, Copenhagen, Denmark; 3Department of Endocrinology, Herlev University Hospital, Herlev, Denmark; 4Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark; 5Department of Health Science and Technology, University of Aalborg, Aalborg, Denmark; 6The Danish heart foundation, Copenhagen, Denmark; 7Department of Endocrinology, Amager and Hvidovre Hospital, Copenhagen, Denmark.


Introduction: Subclinical hypothyroidism (SCH) is a common condition and can lead to impaired systolic and diastolic cardiac function. However, controversy remains over the potential benefits of levothyroxine substitution in patients with SCH and concomitant heart disease. We aimed to examine the effects of levothyroxine treatment on all-cause mortality in patients diagnosed with SCH and heart disease.

Methods: Primary care patients aged 18 years and older with established heart disease (ischemic heart disease, heart failure or cardiac arrhythmia) that underwent thyroid function tests in 2000–2009 were enrolled upon diagnosis of SCH. Exclusion criteria included a history of thyroid dysfunction, thyroid-related medication or medication affecting thyroid function. Patients were stratified according to cashed prescriptions of levothyroxine in a run-in period of 6 months. Risk of all-cause mortality was estimated as incidence rate ratio (IRR) by use of time-dependent Poisson regression models adjusted for age, gender and comorbidity, with patients not receiving levothyroxine as reference.

Results: The total study cohort comprised 814 patients with concomitant SCH and heart disease (mean age 74.1 (S.D.±13.5) years, 65% female). Within the run-in period of the first 6 months 44 (5.4%) patients were prescribed levothyroxine. During a median follow-up time of 5.1 years (IQR 8.7–2.8), 442 (54.3%) patients died. Incidence rates for all-cause mortality were 9.7 and 8.0 per 100 person-years among untreated and levothyroxine-treated patients, respectively. No significantly increased risk of all-cause mortality was found in patients substituted with levothyroxine (adjusted IRR 1.06 (95% CI: 0.69-1.65)).

Conclusion: Levothyroxine substitution in patients with subclinical hypothyroidism and concomitant heart disease is not associated with a significant change in the risk of all-cause mortality in a real-world cohort study.

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