Long-Term Outcome in Levothyroxine Treated Patients With Subclinical Hypothyroidism and Concomitant Heart Disease
Mette Nygaard Andersen1, Anne-Marie Schjerning Olsen1, Jesper Clausager Madsen1
1Department of Cardiology (M.N.A., A.-M.S.O., S.L.K., G.H.G.), Gentofte University Hospital, 2900 Hellerup, Denmark; Elective Laboratory of the Capital Region (J.C.M.), 1112 Copenhagen, Denmark; Department of Endocrinology (J.F.), Herlev University Hospital, 2730 Herlev, Denmark; Faculty of Health Sciences (J.F., G.H.G.), University of Copenhagen, 1165 Copenhagen, Denmark; Department of Health Science and Technology (C.T.-P.), University of Aalborg, 9100 Aalborg, Denmark; The Danish Heart Foundation (G.H.G.), 1120 Copenhagen, Denmark; The National Institute of Public Health (G.H.G.), University of Southern Denmark, 1399 Copenhagen, Denmark; and Department of Endocrinology (C.S.), Amager and Hvidovre University Hospital, 2650 Copenhagen, Denmark.
Insights
Levothyroxine treatment for subclinical hypothyroidism in heart disease patients showed no significant impact on mortality or major adverse cardiac events. This large cohort study found neither benefit nor increased risk associated with the treatment.
Area of Science:
- Cardiology
- Endocrinology
- Public Health
Background:
- Subclinical hypothyroidism (SCH) is prevalent and may impair cardiac function.
- Patients with established heart disease and SCH require careful management.
- The impact of levothyroxine treatment in this specific population remains incompletely understood.
Purpose of the Study:
- To investigate the effects of levothyroxine treatment on cardiac outcomes and mortality in patients with SCH and pre-existing heart disease.
- To assess the safety and efficacy of levothyroxine in managing SCH within a cardiology patient cohort.
Main Methods:
- A register-based historical cohort study design was employed.
- Danish primary care and hospital outpatients (≥18 years) with heart disease and diagnosed SCH between 1997-2011 were included.
- Time-dependent multivariable Poisson regression was used to calculate event rates and incidence rate ratios (IRR) for mortality, MACEs, and hospital admissions.
Main Results:
- The study included 1192 patients with SCH and heart disease; 136 (11.4%) received levothyroxine.
- During a median follow-up of 5.6 years, 694 (58.2%) patients died.
- Levothyroxine treatment was not associated with a significantly increased risk of all-cause mortality (aIRR 1.17), MACE (aIRR 1.08), or hospital admission (aIRR 0.94) compared to no treatment.
Conclusions:
- Levothyroxine treatment in patients with SCH and heart disease did not demonstrate a significant benefit or risk regarding mortality, MACE, or hospital admissions.
- This large real-world cohort study suggests that levothyroxine therapy for SCH in cardiac patients does not alter major adverse outcomes.
- Further research may be warranted to explore potential benefits in specific subgroups or with different treatment strategies.
Context:
Subclinical hypothyroidism is a common condition that may lead to impaired cardiac function.
Objective:
This study sought to examine the effects of levothyroxine treatment in patients with subclinical hypothyroidism and heart disease.
Design:
This was a register-based historical cohort study.
Setting And Participants:
The study was composed of Danish primary care patients and hospital outpatients age 18 years and older with established heart disease who were diagnosed with subclinical hypothyroidism in 1997-2011. Patients were stratified according to whether they claimed a subsequent prescription of levothyroxine. Event rates and incidence rate ratios (IRR) were calculated by use of time-dependent multivariable Poisson regression models.
Main Outcome Measures:
Measures included all-cause mortality and major adverse cardiac events (MACEs), defined as cardiovascular death, fatal or nonfatal myocardial infaction and stroke, and all-cause hospital admissions.
Results:
Of 61 611 patients with a diagnosis of cardiac disease having their first time thyroid function testing, 1192 patients with subclinical hypothyroidism (mean age 73.6 [SD ± 13.3] y, 63.8% female) were included, of whom 136 (11.4%) were treated with levothyroxine. During a median follow-up time of 5.6 y (interquartile range, 6.5 y), 694 (58.2%) patients died. Patients treated with levothyroxine displayed no significantly increased risk of all-cause mortality (adjusted IRR, 1.17; 95% confidence interval [CI], 0.90-1.52), MACE (adjusted IRR, 1.08; 95% CI, 0.80-1.45), or hospital admission (adjusted IRR, 0.94; 95% CI, 0.71-1.24), when compared with patients not treated with levothyroxine.
Conclusion:
Levothyroxine treatment in patients with subclinical hypothyroidism and heart disease was not associated with a significant benefit nor risk of all-cause mortality, MACE, or hospital admission in this large real-world cohort study.
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