Outcomes of Thyroid Dysfunction in People Aged Eighty Years and Older: An Individual Patient Data Meta-Analysis of Four Prospective Studies (Towards Understanding Longitudinal International Older People Studies Consortium)

Management of thyroid dysfunction and thyroid nodules in the ageing patient

Thyroid dysfunction is a common endocrine disorder in the general population, with a reported prevalence of 10-15%. However, this rate is even higher in older adults, with an estimated prevalence of ≈25% in some populations. Since elderly patients usually present more comorbidities than younger individuals, thyroid dysfunction may carry a synergistic negative health impact, mainly due to increased cardiovascular disease risk. Moreover, thyroid dysfunction in the elderly can be more difficult to diagnose due to its subtle or even asymptomatic clinical presentation, and the interpretation of thyroid function tests may be affected by drugs that interfere with thyroid function or by the coexistence of several diseases. On the other hand, thyroid nodules are also a prevalent condition in older adults, and its incidence increases with age. The assessment and management of thyroid nodules in the ageing patient should take into account several factors, as risk stratification, thyroid cancer biology, patient´s overall health, comorbidities, treatment preferences, and goals of care. In this review article, we summarize the current knowledge on the pathophysiology, diagnosis, and therapeutic management of thyroid dysfunction in elderly patients and we also review how to identify and manage thyroid nodules in this population.

Management of Subclinical Hypothyroidism: A Focus on Proven Health Effects in the 2023 Korean Thyroid Association Guidelines

Subclinical hypothyroidism (SCH) is characterized by elevated thyroid-stimulating hormone (TSH) and normal free thyroxine levels. The Korean Thyroid Association recently issued a guideline for managing SCH, which emphasizes Korean-specific TSH diagnostic criteria and highlights the health benefits of levothyroxine (LT4) treatment. A serum TSH level of 6.8 mIU/L is presented as the reference value for diagnosing SCH. SCH can be classified as mild (TSH 6.8 to 10.0 mIU/L) or severe (TSH >10.0 mIU/L), and patients can be categorized as adults (age <70 years) or elderly (age ≥70 years), depending on the health effects of LT4 treatment. An initial increase in serum TSH levels should be reassessed with a subsequent measurement, including a thyroid peroxidase antibody test, preferably 2 to 3 months after the initial assessment. While LT4 treatment is not generally recommended for mild SCH in adults, it is necessary for severe SCH in patients with underlying coronary artery disease or heart failure and it may be considered for those with concurrent dyslipidemia. Conversely, LT4 treatment is generally not recommended for elderly patients, regardless of SCH severity. For those SCH patients who are prescribed LT4 treatment, the dosage should be personalized, and serum TSH levels should be regularly monitored to maintain the optimal LT4 regimen.

Subclinical Hypothyroidism and Clinical Outcomes After Percutaneous Coronary Intervention: A Meta-Analysis

While subclinical hypothyroidism (SCH) was reportedly associated with an increased risk of cardiovascular mortality, the relationship between SCH and clinical outcomes of patients undergoing percutaneous coronary intervention (PCI) is uncertain. The aim of this study was to assess the association of SCH and cardiovascular outcomes in patients undergoing PCI. We searched PubMed, Embase, Scopus, and CENTRAL databases from its inception until April 1, 2022 for studies comparing the outcomes between SCH and euthyroid patients undergoing PCI. Outcomes of interest include cardiovascular mortality, all-cause mortality, myocardial infarction (MI), major adverse cardiovascular and cerebrovascular events (MACCE), repeat revascularization and heart failure. Outcomes were pooled using the DerSimonian and Laird random-effects model and reported as risk ratios (RR) and 95% confidence intervals (CI). A total of 7 studies involving 1132 patients with SCH and 11,753 euthyroid patients were included in the analysis. Compared with euthyroid patients, patients with SCH had significantly higher risk of cardiovascular mortality (RR 2.16, 95% CI: 1.38-3.38, P < 0.001), all-cause mortality (RR 1.68, 95% CI: 1.23-2.29, P = 0.001) and repeat revascularization (RR 1.96, 95% CI: 1.08-3.58, P = 0.03). However, there were no differences between both groups in terms of incidence of MI (RR 1.81, 95% CI: 0.97-3.37, P = 0.06), MACCE (RR 2.24, 95% CI: 0.55-9.08, P = 0.26) and heart failure (RR 5.38, 95% CI: 0.28-102.35, P = 0.26). Our analysis suggests among patients undergoing PCI, SCH was associated with increased risk of cardiovascular mortality, all-cause mortality and repeat revascularization compared to euthyroid patients.

High Thyrotropin Levels and Risk of Mortality in the Elderly With Subclinical Hypothyroidism: A Systematic Review and Meta-analysis

OBJECTIVE

This study aims to determine whether elevated endogenous thyrotropin levels contribute to an increased risk of adverse outcomes, such as all-cause mortality in older adults with subclinical hypothyroidism.

METHODS

Eight electronic databases were searched for relevant articles from inception until March 23, 2022. Cohort studies assessing the association between thyrotropin levels and the risk of mortality among older adults aged ≥60 years with subclinical hypothyroidism were eligible. The outcomes of interest were either all-cause or cardiovascular-related mortality. Two independent researchers assessed the eligibility of the studies and collected data through a previously defined data extraction form. The Newcastle-Ottawa Scale was used to evaluate the quality of evidence, and multivariate-adjusted hazard ratios (HRs) (95% Cl) were collected as the necessary risk estimate for synthesis. Random-effects models were applied for meta-analysis.

RESULTS

Overall, 13 studies involving 44 514 participants were included in this meta-analysis. There were no significant differences in the risk of all-cause mortality (pooled HR: 1.18 [95% Cl: 0.95, 1.45], I² = 94%) and cardiovascular-related mortality (pooled HR: 1.08 [95% Cl: 0.94, 1.23], I² = 0%) between euthyroid older adults and older adults with subclinical hypothyroidism. The results remained the same when only older adults with thyrotropin ≥10 mIU/L were assessed (pooled HR for all-cause mortality and cardiovascular-related mortality, respectively: 1.53 [95% Cl: 0.81, 2.88], I² = 22%, 1.35 [95% Cl: 0.63, 2.86], I² = 43%).

CONCLUSION

High thyrotropin levels are not associated with increased risk for all-cause mortality as well as cardiovascular-related mortality in older adults aged ≥60 years with subclinical hypothyroidism, suggesting an unnecessity in initialing treatment.

Association between thyroid function, nursing home admission and mortality in community-dwelling adults over 80 years

PURPOSE

Thyroid deficiency may reduce mortality in older adults, but older adults prioritize independence over merely staying alive. We investigated the association between thyroid dysfunction and nursing home admission and all-cause mortality in community-dwelling older adults over 80.

METHODS

We conducted a retrospective population-based open cohort study using data from laboratory registries covering 75% of Denmark supplemented by national registries. We included all community-dwelling older adults over 80 years with a first TSH measurement between 1996 and 2019. Participants with prior thyroid disorders or medication affecting the thyroid were excluded. Participants were followed from inclusion until nursing home admission, death or loss to follow-up due to emigration.

RESULTS

We included 272,495 participants at baseline. Median follow-time was 3.71 years in analyses of nursing home admissions and 4.00 years for all-cause mortality. Hypothyroidism was associated with lower nursing home admission (TSH 5-10 mIU/l: HR 0.85, 95% CI: 0.80-0.91, P < 0.001); TSH >10 mIU/l HR 0.68, 95% CI: 0.54-0.85, P = 0.001) and with reduced all-cause mortality (TSH >10 mIU/l: HR 0.81, 95% CI: 0.70-0.93, P = 0.002). The association between hyperthyroidism and nursing home admission was of little clinical significance while hyperthyroidism was associated with increased all-cause mortality hazard both for low (HR 1.16, 95% CI 1.13-1.19, P < 0.001) and suppressed (HR 95% CI: 1.14 1.07-1.21, P < 0.001) TSH.

CONCLUSION

Hypothyroidism is associated with a reduced nursing home admission hazard and to a lesser extent all-cause mortality in community-dwelling adults over 80 years, while hyperthyroidism is associated with increased all-cause mortality but not hazard of nursing home admission.

Hypothyroidism: The difficulty in attributing symptoms to their underlying cause

Common symptoms of overt hypothyroidism are non-specific and include fatigue, lethargy, and dry skin. Although the diagnosis is considered to be straightforward, no single symptom can be used to identify patients with overt hypothyroidism, while many patients with subclinical hypothyroidism are asymptomatic. A large population-based study on the spectrum of symptoms in subclinical hypothyroidism showed similar rates of thyroid disease-related symptoms compared with euthyroid subjects, while the TSH concentration had no impact on symptom score. Together, these findings make it challenging to attribute symptoms to their underlying cause. This is also true in the case of unexplained persistent symptoms in levothyroxine-treated patients. Although generally considered a life-long replacement therapy, successful thyroid hormone discontinuation resulting in euthyroidism has been reported in approximately one third of patients. Thus, we overtreat patients with (subclinical) hypothyroidism, highlighting the importance of reliable diagnostic criteria. The diagnostic process, including the implementation of robust TSH and FT4 reference intervals, is especially challenging in specific situations including aging, pregnancy, non-thyroidal illness, and central hypothyroidism. There is a clear need for improved adherence to current guidelines from scientific societies and for willingness to manage symptoms without a clear pathological correlate, especially in the case of mild TSH elevations. This review will highlight recent literature on this topic and offers some practice points.

Vascular disease and apathy symptoms in the very old: A cross-sectional and longitudinal meta-analysis of individual participant data

OBJECTIVES

Previous findings suggest a vascular foundation underlying apathy, but transdiagnostic and prospective evidence on vascular apathy is scarce. This study examines the association between vascular disease and the presence and development of apathy symptoms in the very old.

METHODS

Four cohorts of the Towards Understanding Longitudinal International older People Studies (TULIPS)-consortium were included in a two-staged, individual participant data meta-analysis using generalized linear mixed models. Vascular disease was defined as a history of any clinical atherosclerotic pathology (angina pectoris, myocardial infarction, intermittent claudication, transient ischemic attack, stroke or related surgeries) and was related to apathy symptoms as repeatedly measured by the Geriatric Depression Scale (GDS-3A ≥2) over a maximum of 5 years.

RESULTS

Of all 1868 participants (median age 85 years old), 53.9% had vascular disease and 44.3% experienced apathy symptoms. Participants with vascular disease had a 76% higher risk of apathy symptoms at baseline (odds ratio (OR) 1.76, 95% confidence interval (CI) 1.32-2.35), irrespective of depressive symptoms and only partially explained by stroke. Conversely, there was no association of vascular disease with the occurrence of apathy symptoms longitudinally, both in those with apathy at baseline (OR 1.00, 95% CI 0.84-1.20) and without (OR 0.96, 95% CI 0.84-1.09).

CONCLUSIONS

Vascular disease in the very old is associated with apathy symptoms cross-sectionally, but not proven longitudinally, independent of depressive symptoms. These findings query a vascular cause underlying apathy symptoms. However, the consistency of our cross-sectional findings in direction and magnitude across the TULIPS-consortium do emphasize international relevance of the interplay of vascular factors and apathy in advanced age, which meaning needs further unravelling.

Approach to adult patients with primary hypothyroidism in some special situations: a position statement from the Thyroid Department of the Brazilian Society of Endocrinology and Metabolism (SBEM)

Primary hypothyroidism is a common disorder in clinical practice. The management of most cases of hypothyroidism is usually straightforward, but the best approach in some special situations may raise questions among physicians. This position statement was prepared by experts from the Brazilian Society of Endocrinology and Metabolism to guide the management of three special situations, namely, hypothyroidism in the elderly, subclinical hypothyroidism in patients with heart disease, and difficult-to-control hypothyroidism. The authors prepared the present statement after conducting a search on the databases MEDLINE/PubMed, LILACS, and SciELO and selecting articles with the best evidence quality addressing the selected situations. The statement presents information about the current approach to patients in these special situations.

Update on subclinical thyroid dysfunction

Subclinical thyroid dysfunction is defined by serum thyroid-stimulating hormone (TSH) levels either greater or less than the reference range with normal thyroxine (T4) concentrations, and consists of subclinical hypothyroidism (SCH) and subclinical hyperthyroidism (SCHyper). For the proper diagnosis of SCH, it is most important to be able to correctly evaluate the serum TSH levels, which have numerous unique characteristics. We also need to be versed in TSH harmonization, which was recently launched world-wide. In this review, we will attempt to determine the best clinical approaches to the treatment of subclinical thyroid dysfunction based on recent guidelines published from several countries and novel findings of several recent large-scale clinical studies.

The impact of the management strategies for patients with subclinical hypothyroidism on long-term clinical outcomes: An umbrella review

AIM

This umbrella review summarises and compares synthesised evidence on the impact of subclinical hypothyroidism and its management on long-term clinical outcomes.

METHODS

We conducted comprehensive searches on MEDLINE, EMBASE, Scopus, Web of Science, Cochrane Database of Systematic Reviews, JBI Evidence Synthesis, the PROSPERO register, Epistemonikos Database and PDQ Evidence from inception to February and July 2021 using keywords on subclinical hypothyroidism, treatment with levothyroxine, monitoring and primary outcomes (all-cause mortality, cardiovascular events, stroke, frailty fractures and quality of life). Only systematic reviews and meta-analyses on adult patient populations were considered. Study selection, data extraction and quality appraisal using AMSTAR-2 were done independently by two reviewers and discrepancies were resolved through discussion. Overlap across the selected reviews was also assessed, followed by a narrative synthesis of findings.

RESULTS

A total of 763 studies were identified from literature searches; 20 reviews met inclusion criteria. Methodological quality ratings were high (n = 8), moderate (n = 7), and low (n = 5), but no reviews were excluded on this basis. Though there was slight overlap across all reviews, some pairwise comparisons had high corrected covered area scores. Compared to euthyroidism, untreated subclinical hypothyroidism was associated with a higher risk of cardiovascular events or death if Thyroid Stimulating Hormone was above 10mIU/L at baseline. Treatment was associated with a lower risk of death from all causes for patients younger than 70 years and possibly better cognitive and quality of life scores than untreated individuals. Evidence on the risk of strokes and fractures was inconclusive.

CONCLUSION

In the long term, treatment of subclinical hypothyroidism may be beneficial for some patient groups. However, the findings of this review are negatively impacted by the relative sparseness and poor quality of available evidence. Additional large and adequately powered studies are needed to investigate this topic further.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO (CRD42021235172).

Subclinical hypothyroidism in older individuals

Subclinical hypothyroidism, which is defined as a thyroid-stimulating hormone concentration higher than the reference range (generally 4·5 mIU/L or higher) with normal free thyroxine concentrations, is frequently found in older individuals. International guidelines differ in recommendations for management of subclinical hypothyroidism in older individuals. We assessed published data during the past decade on the clinical significance and treatment of subclinical hypothyroidism in individuals aged 65 years and older. Meta-analyses, randomised clinical trials, and cohort studies are discussed in this narrative Review. Studies showed no significantly increased incidence in adverse cardiovascular, musculoskeletal, or cognitive outcomes in individuals aged 65 years or older when serum thyroid-stimulating hormone concentration was 4·5-7·0 mIU/L versus a euthyroid group. Moreover, in older individuals with subclinical hypothyroidism, symptoms of hypothyroidism and cardiac and bone parameters did not improve after levothyroxine treatment. These data suggest that treatment with levothyroxine should be considered for individuals aged 65 years or older with subclinical hypothyroidism when thyroid-stimulating hormone concentration is persistently 7 mIU/L or higher and to not initiate treatment with thyroid-stimulating hormone concentrations of less than 7 mIU/L. Levothyroxine doses should be personalised according to age, comorbidities, and life expectancy.

Treating hypothyroidism is not always easy: When to treat subclinical hypothyroidism, TSH goals in the elderly, and alternatives to levothyroxine monotherapy

The majority of patients with hypothyroidism feel better when levothyroxine treatment restores thyroid-stimulating hormone (TSH) concentrations to normal. Increasingly, a significant minority of patients remain symptomatic and are dissatisfied with their treatment. Overzealous treatment of symptomatic patients with subclinical hypothyroidism may contribute to dissatisfaction among hypothyroidism patients, as potential hypothyroid symptoms in patients with minimal hypothyroidism rarely respond to treatment. Thyroid hormone prescriptions have increased by 30% in the United States in the last decade. The diagnosis of subclinical hypothyroidism should be confirmed by repeat thyroid function tests ideally obtained at least 2 months later, as 62% of elevated TSH levels may revert to normal spontaneously. Generally, treatment is not necessary unless the TSH exceeds 7.0-10 mIU/L. In double-blinded randomized controlled trials, treatment does not improve symptoms or cognitive function if the TSH is less than 10 mIU/L. While cardiovascular events may be reduced in patients under age 65 with subclinical hypothyroidism who are treated with levothyroxine, treatment may be harmful in elderly patients with subclinical hypothyroidism. TSH goals are age dependent, with a 97.5 percentile (upper limit of normal) of 3.6 mIU/L for patients under age 40, and 7.5 mIU/L for patients over age 80. In some hypothyroid patients who are dissatisfied with treatment, especially those with a polymorphism in type 2 deiodinase, combined treatment with levothyroxine and liothyronine may be preferred.

Thyroid and heart, a clinically relevant relationship

BACKGROUND

Thyroid disorders, both overt and subclinical, are highly prevalent conditions in the general population. Although a clear relationship between overt thyroid dysfunctions and cardiovascular complications has long been established, data regarding subclinical thyroid dysfunction are by far more controversial.

PURPOSE

The present review will be aimed at providing a summary of most recent evidence coming from meta-analyses regarding the complex relationship between thyroid dysfunction and cardiovascular disease.

CONCLUSIONS

The review will summarize, in the first part, the physiopathological link between thyroid hormone imbalances and the cardiovascular system. In the second part the review will outline the evidence coming from meta-analyses regarding the cardiovascular risk related with both overt and subclinical thyroid dysfunctions. Particular attention will be put towards studies showing data stratified for patient's age, TSH levels and pre-existing cardiovascular disease. Finally, an overview regarding the effects of specific therapy for subclinical thyroid diseases in terms of amelioration of cardiovascular outcomes will be included.

Risk of All-Cause Mortality in Levothyroxine-Treated Hypothyroid Patients: A Nationwide Korean Cohort Study

BACKGROUND

Although hypothyroidism is associated with various comorbidities, its relationship with increased all-cause mortality remains controversial. The aim of this nationwide retrospective cohort study was to investigate whether hypothyroid patients treated with levothyroxine had increased mortality compared to controls.

METHODS

Hypothyroid subjects were identified through the Korean National Health Insurance Service Claims database between 2008 and 2017. Hypothyroidism in this study was defined as overt hypothyroidism treated with long-term prescription of levothyroxine (>6 months). After 1:3 age-, sex- and index year-matching, 501,882 patients with newly diagnosed hypothyroidism and 1,505,646 controls without hypothyroidism were included.

RESULTS

During a mean follow-up of 6 years, 25,954 (5.2%) hypothyroid patients and 59,105 (3.9%) controls died. Hypothyroidism was significantly associated with increased all-cause mortality (adjusted hazard ratio [HR], 1.14; 95% confidence interval [CI] 1.12-1.16) even with levothyroxine treatment. When stratified by age, sex, and cardiovascular disease risk, independent associations between hypothyroidism and mortality remained significant in all subgroups. The risk of mortality was higher in the < 65 age group (HR: 1.25, 95% CI: 1.22-1.29), men (HR: 1.28, 95% CI: 1.25-1.31), and the high cardiovascular disease risk group (HR: 1.31, 95% CI: 1.29-1.34). The mortality rate of hypothyroid patients was highest within 1 year of treatment and decreased with time.

CONCLUSION

This nationwide, population-based cohort study showed that all-cause mortality was significantly higher in levothyroxine-treated hypothyroid patients than in non-hypothyroid controls. This association remained significant regardless of age, sex, and cardiovascular disease risk.