Study of Optimal Replacement of Thyroxine in the Elderly (SORTED) - results from the feasibility randomised controlled trial

Assessing the cardiovascular effects of levothyroxine use in an ageing United Kingdom population (ACEL-UK) protocol: a cohort and target trial emulation study

BACKGROUND

Subclinical hypothyroidism is diagnosed when serum thyroid stimulating hormone levels are higher whilst free thyroxine levels remain within their respective reference ranges. These reference ranges are uniformly applied in all adults, despite serum thyroid stimulating hormone levels naturally increasing with age. Research has found that mildly elevated thyroid stimulating hormone levels may be associated with some benefits in ageing patients, including reduced mortality and better cardiorespiratory fitness. Levothyroxine is typically prescribed to patients with hypothyroidism, but no conclusive evidence exists on whether levothyroxine therapy is beneficial or detrimental in older subclinical hypothyroid patients. Despite this, prescriptions for levothyroxine are increasing year-on-year. This study aims to determine if receiving levothyroxine affects the cardiovascular and bone health outcomes of subclinical patients in primary care aged 50 years and over.

METHODS

This project includes a retrospective cohort analysis and a target trial emulation study using electronic patient records collected between 2006 and 2021 and recorded in The Health Improvement Network database. The primary outcome of this study is to compare the cardiovascular outcomes of subclinical hypothyroid patients aged over 50 years treated with levothyroxine compared to those untreated. Secondary outcomes are bone health and all-cause mortality outcomes. Descriptive and inferential statistics will both be employed to analyse the data. Secondary analysis will explore confounding factors, including age, sex, smoking status, body mass index, co-morbidities, and levothyroxine dosage.

DISCUSSION

There needs to be a greater understanding of the potential risks of the current treatment for older patients with subclinical hypothyroidism in a primary care setting. We will investigate the clinical importance of this issue and whether older subclinical hypothyroid patients have poorer outcomes when treated. Clarifying this concern may help address the healthcare resource implications of ageing patients being misclassified as having mild hypothyroidism, as these patients are more likely to repeat their blood tests. This could reduce prescription wastage and improve patient outcomes and quality of life in the ageing population.

TRIAL REGISTRATION

Not applicable.

Subclinical hypothyroidism, outcomes and management guidelines: a narrative review and update of recent literature

Subclinical hypothyroidism (SCH) is diagnosed when serum thyroid stimulation hormone (thyrotropin; TSH) levels are above the reference range, accompanied by levels of free thyroxine within its reference range. The management of SCH remains a diagnostic and therapeutic challenge despite many years of research relating to its epidemiology, aetiology, effectiveness of treatment and safety. European Thyroid Association (ETA) guidelines for the management of SCH were published almost a decade ago. This narrative review summarizes the clinical literature relating to SCH and outcomes since the publication of these guidelines. Clinical evidence emerging during the previous decade generally supports the view that SCH is associated with adverse outcomes to an extent that is intermediate between euthyroidism and overt hypothyroidism although evidence that treatment with thyroid hormone replacement is beneficial is lacking. Accordingly, the rationale for the recommendations for intervention in the ETA guidelines based on the age of the patient, level of serum TSH, symptoms and comorbidities remains valid today.

Prevalence and risk factors of untreated thyroid dysfunctions in the older Caucasian adults: Results of PolSenior 2 survey

Introduction

To determine the prevalence of treated and untreated thyroid dysfunction and to identify factors associated with increased risk of undiagnosed thyroid dysfunction in older adults.

Methods

The population of 5987 community-dwelling Polish Caucasian seniors aged 60 years and above who participated in the PolSenior 2 study (2018–2019). Population-based cross-sectional multidisciplinary study in design. Data from structured questionnaires, geriatric tests, and scales were obtained from all study participants who underwent anthropometric and blood pressure measurements during three home visits. Assessment of thyroid function was based on TSH serum measurements.

Results

The prevalence of thyroid dysfunction in the Polish population aged 60 years or above was estimated at 15.5% (21.5% in women and 7.2% in men), with 3.2% of undiagnosed individuals among them. The prevalence of hypothyroidism and hyperthyroidism in the studied group was 13.9% (19.4% in women and 6.3% in men) and 1.6% (2.1% in women and 0.9% in men) respectively, untreated hypothyroidism was revealed in 21.9% (in 160 out of 732 subjects) and untreated hyperthyroidism in 34.2% of subjects (in 41 out of 120 participants). In multiple regression analysis independent risk factors for thyroid disorders being untreated were older age (> 75 years), male sex, a low education level (primary or lower), and low utilization of medical services.

Conclusions

One-fifth of Polish Caucasian seniors with hypothyroidism and one-third with hyperthyroidism are untreated. Older, poorly educated and rarely utilizing medical services seniors, especially men, are more frequently untreated for thyroid dysfunction and some of them do not benefit from contemporary achievements in medicine.

Thyroid Disease in Aging

Thyroid disease is common in older adults. Increasing numbers of older persons will present to physicians for care in the United States as the U.S. and world populations age. It is expected that by the year 2030 that 19-20% of the U.S. population will be over 65-years old and by 2040 that 25% of the U.S. population will be over 65-years old. It is important for clinicians to be familiar with thyroid disease in this population because of its impact on the patient's functional and cognitive state. Thyroid disease often presents in older adults with nonspecific presentations such as falls, weakness, or cognitive impairment. Thyroid abnormalities may also be detected with routine testing.

Treatment of subclinical hypothyroidism: assessing when treatment is likely to be beneficial

Introduction: Subclinical hypothyroidism (SCH) is a common condition diagnosed in up to 16% of the population. SCH is diagnosed when serum TSH is high and circulating thyroid hormones are within the reference range. SCH is considered to be a mild form of thyroid failure by some due to the log-linear relationship between TSH and thyroid hormones. Nevertheless, it is unclear whether the treatment of SCH with thyroid hormones is beneficial, and hence, it is not surprising that expert opinions and recommendations from societies differ in their opinions on how best to manage SCH.Areas covered: This article reviews the currently available evidence pertaining to SCH and provides recommendations as to when treatment of SCH should be considered. An electronic search of PubMed from 1970 to 2019 was performed and systematically reviewed studies assessing the effects of treatment in SCH. The main areas that are considered are the effects of treatment on symptoms and quality of life, and important clinical consequences including psychocognitive outcomes and cardiovascular events.Expert opinion: Treatment of SCH with thyroid hormones is debated and the current literature in this area lacks clarity. We provide an evidence-based recommendation for when treatment of SCH with thyroid hormones should be considered.

Hypothyroidism Treatment Among Older Adults: Evidence from a Claims Database

INTRODUCTION

Hypothyroidism is a common but often unrecognized condition associated with significant morbidity in the older adult population. This study characterizes a large population of older adults diagnosed with hypothyroidism and examines concordance of their treatment with recommendations from expert bodies, e.g., the American Thyroid Association and American Association of Clinical Endocrinologists.

METHODS

Individuals seen in general and/or specialty practices who were age ≥ 65 years and diagnosed with hypothyroidism were included in this observational, retrospective cohort study using a large US claims database. Analyses describe the population and examine the prevalence of hypothyroidism, treatment with levothyroxine and, among those treated, whether TSH laboratory values are within a guideline-recommended target range.

RESULTS

Prevalence of hypothyroidism in this older adult population increased from 5.62% to 8.24% over the 2007-2015 period. Among older adults diagnosed with hypothyroidism (N = 4025), a substantial proportion (28.0%) did not receive levothyroxine therapy, and, of those who were receiving such therapy (N = 2899), 32.9% did not have evidence of being monitored to determine whether the dosage was appropriate. Moreover, the laboratory results of those who were treated suggest that a significant proportion (17.4%) had a TSH level above the recommended target range, while TSH levels for a smaller proportion (3.7%) were below target.

CONCLUSIONS

Many older adults diagnosed with hypothyroidism may not have received medical care complying with clinical practice guidelines. Results of this study reveal a number of areas to target to potentially improve the treatment of older adults with hypothyroidism.

Age-Related Serum Thyroid-Stimulating Hormone Reference Range in Older Patients Treated with Levothyroxine: A Randomized Controlled Feasibility Trial (SORTED 1)

INTRODUCTION

Serum thyroid-stimulating hormone (TSH) increases with age but target TSH is similar in younger and older hypothyroid patients on treatment. It is unknown if quality of life (QoL), hypothyroid symptoms and cardiovascular risk factors change in older hypothyroid patients treated to an age-appropriate reference range.

OBJECTIVE

To assess if a higher target serum TSH of 4.01-8.0 mU/L is feasible in, and acceptable to, older treated hypothyroid patients.

METHODS

A single-blind (participant) randomised controlled feasibility trial involving 48 hypothyroid patients aged ≥80 years on established and stable levothyroxine (LT4) therapy with serum TSH levels within the standard reference range (0.4-4.0 mU/L) was conducted. Standard (0.4-4.0 mU/L) or higher (4.1-8.0 mU/L) TSH target (standard TSH [ST] or higher TSH [HT] groups) LT4 for 24 weeks was administered. The outcome measures evaluated were thyroid function tests, QoL, hypothyroid symptoms, cardiovascular risk factors and serum marker of bone resorption in participants that completed the trial (n = 21/24 ST group, n = 19/24 HT group).

RESULTS

At 24 weeks, in the ST and HT groups, respectively, median (interquartile range) serum TSH was 1.25 (0.76-1.72) and 5.50 (4.05-9.12) mU/L, mean (± SD) free thyroxine (FT4) was 19.4 ± 3.5 and 15.9 ± 2.4 pmol/L, and daily LT4 dose was 82.1 ± 26.4 and 59.2 ± 23.9 µg. There was no suggestion of adverse impact of a higher serum TSH in the HT group with regard to any of the outcomes assessed.

CONCLUSIONS

In hypothyroid patients aged ≥80 years on LT4 therapy for 24 weeks, there was no evidence that a higher target serum TSH was associated with an adverse impact on patient reported outcomes, cardiovascular risk factors or bone resorption marker over 24 weeks. Longer-term trials assessing morbidity and mortality outcomes and health-utility in this age group are feasible and should be performed.

Hypothyroidism in the older population

BACKGROUND

Both overt hypothyroidism as well as minor elevations of serum thyrotropin (TSH) levels associated with thyroid hormones within their respective reference ranges (termed subclinical hypothyroidism) are relatively common in older individuals. There is growing evidence that treatment of subclinical hypothyroidism may not be beneficial, particularly in an older person. These findings are relevant at a time when treatment with thyroid hormones is increasing and more than 10-15% of people aged over 80 years are prescribed levothyroxine replacement therapy.

MAIN BODY

The prevalence of hypothyroidism increases with age. However, the reference range for TSH also rises with age, as the population distribution of TSH concentration progressively rises with age. Furthermore, there is evidence to suggest that minor TSH elevations are not associated with important outcomes such as impaired quality of life, symptoms, cognition, cardiovascular events and mortality in older individuals. There is also evidence that treatment of mild subclinical hypothyroidism may not benefit quality of life and/or symptoms in older people. It is unknown whether treatment targets should be reset depending on the age of the patient. It is likely that some older patients with non-specific symptoms and incidental mild subclinical hypothyroidism may be treated with thyroid hormones and could potentially be harmed as a result. This article reviews the current literature pertaining to hypothyroidism with a special emphasis on the older individual and assesses the risk/benefit impact of contemporary management on outcomes in this age group.

CONCLUSIONS

Current evidence suggests that threshold for treating mild subclinical hypothyroidism in older people should be high. It is reasonable to aim for a higher TSH target in treated older hypothyroid patients as their thyroid hormone requirements may be lower. In addition, age-appropriate TSH reference ranges should be considered in the diagnostic pathway of identifying individuals at risk of developing hypothyroidism. Appropriately designed and powered randomised controlled trials are required to confirm risk/benefit of treatment of subclinical hypothyroidism in older people. Until the results of such RCTs are available to guide clinical management international guidelines should be followed that advocate a conservative policy in the management of mild subclinical hypothyroidism in older individuals.

Systemic Thyroid Hormone Status During Levothyroxine Therapy In Hypothyroidism: A Systematic Review and Meta-Analysis

CONTEXT

The standard of care for overt hypothyroidism is levothyroxine at doses that normalize serum TSH levels. Whether this approach universally restores thyroid hormone signaling is unknown.

OBJECTIVE

To review studies of overt hypothyroidism in which participants were treated with levothyroxine to normalize serum TSH levels and measured other objective markers of thyroid hormone signaling.

DESIGN

Databases were searched for studies that reported objective markers of thyroid hormone signaling (serum low-density lipoprotein (LDL), total cholesterol (TC), sex hormone-binding globulin (SHBG), creatine kinase and/or ferritin levels; cognition, energy expenditure, and/or renal function) in levothyroxine monotherapy for overt, primary hypothyroidism among nonpregnant adults with normal serum TSH levels. For studies with LDL, TC and SHBG outcomes, data were pooled using random effects meta-analysis.

RESULTS

A total of 99 studies met inclusion criteria, including 65 that reported serum cholesterol data. Meta-analysis showed that levothyroxine-treated hypothyroid participants with normal serum TSH levels had 3.31 ± 1.64 mg/dL higher serum LDL levels (p=0.044) and 9.60 ± 3.55 mg/dL higher serum TC levels (p=0.007) compared to controls. In studies that did not concomitantly assess healthy controls, serum LDL levels were 138.3 ± 4.6 mg/dL (p<0.001) and serum TC levels were 209.6 ± 3.4 mg/dL (p<0.001). Meta-analysis of 2 studies showed no significant difference between SHBG levels of levothyroxine-treated participants and controls.

CONCLUSIONS

In studies that utilized levothyroxine monotherapy at doses that normalized the serum TSH for overt, primary hypothyroidism, not all systemic biological markers of thyroid hormone signaling were normalized, including serum LDL and TC levels.

Older patients' experience of primary hypothyroidism: A qualitative study

BACKGROUND

Primary hypothyroidism is a common endocrine disorder, more so in an increasing UK ageing population. There is no qualitative research examining the older patient perspective of symptoms, treatment and self-management of hypothyroidism.

OBJECTIVE

In this study we explored the experience of hypothyroidism in older people and examined how this may influence their understanding and acceptance of diagnosis, treatment with Levothyroxine and the monitoring process.

DESIGN

We conducted semi-structured interviews with 18 participants aged between 80 and 93 years. Interview transcripts were analysed using a thematic approach.

RESULTS

The themes involved older individuals' knowledge about symptoms, confidence in diagnosis and understanding of clinical management regimen to understand hypothyroidism. Interpretation of the themes was informed by the Health Belief Model.

CONCLUSION

Our findings can help to inform the development of interventions by treating clinicians and support staff to engage older patients in the long-term management of this chronic condition.

Treated hypothyroidism is associated with cerebrovascular disease but not Alzheimer's disease pathology in older adults

Thyroid hormone disease is common among older adults and is associated with cognitive impairment. However, pathologic correlates are not well understood. We studied pathologic and clinical factors associated with hypothyroidism, the most common manifestation of thyroid disease, in research subjects seen annually for clinical evaluations at U.S. Alzheimer's Disease Centers. Thyroid disease and treatment status were assessed during clinician interviews. Among autopsied subjects, there were 555 participants with treated hypothyroidism and 2146 without known thyroid disease; hypothyroidism was associated with severe atherosclerosis (odds ratio: 1.35; 95% confidence interval: 1.02, 1.79) but not Alzheimer's disease pathologies (amyloid plaques or neurofibrillary tangles). Among participants who did not undergo autopsy (4598 with treated hypothyroidism and 20,945 without known thyroid hormone disease), hypercholesterolemia and cerebrovascular disease (stroke and/or transient ischemic attack) were associated with hypothyroidism, complementing findings in the smaller autopsy sample. This is the first large-scale evaluation of neuropathologic concomitants of hypothyroidism in aged individuals. Clinical hypothyroidism was prevalent (>20% of individuals studied) and was associated with cerebrovascular disease but not Alzheimer's disease-type neuropathology.

Prevalence of treated hypothyroidism in the community: Analysis from general practices in North-East England with implications for the United Kingdom

OBJECTIVE

Hypothyroidism is more frequently diagnosed in women and older individuals. It has been suggested that the prevalence of hypothyroidism and the number of prescriptions for thyroid hormones are increasing. However, despite hypothyroidism being a common medical condition, contemporary data on prevalence, particularly across the various age groups, is limited.

DESIGN

Information regarding number of individuals diagnosed with treated hypothyroidism (defined as patients prescribed levothyroxine) across ten General Practices (total population of 66 843) in the North-East of England in 2016 was obtained in an anonymized manner. Total as well as age group-specific point prevalence rates were calculated. In addition, corresponding population data for the United Kingdom were acquired, and national total and age-specific hypothyroidism prevalence rates were estimated.

RESULTS

The overall prevalence of hypothyroidism in this community sample was 4.5% (n = 3004). Prevalence increased across the age groups from 0.1% in children aged 0-10 years to 15.1% in those aged more than 90 years. After adjusting for demographic differences between the North-East England and UK populations, it is estimated that the total UK-wide prevalence of hypothyroidism in 2016 is 3.6%; affecting more than 2.3 million individuals including nearly 800 000 individuals aged >70 years.

CONCLUSIONS

Hypothyroidism affects millions of individuals in the UK and is currently a prevalent diagnosis in more than 1 in 10 individuals aged above 70 years. As the population ages this number is likely to increase. The clinical and economic effects of current management strategies for hypothyroidism, particularly in the older population, need to be evaluated.

Subclinical hypothyroidism: Should we treat?

Subclinical hypothyroidism (also known as compensated hypothyroidism or mild hypothyroidism) is a condition associated with a raised serum concentration of thyroid stimulating hormone (TSH) but a normal serum free thyroxine (FT4). It is common, affecting about 10% of women above the age of 55 years. Autoimmunity is the commonest cause of subclinical hypothyroidism. About 2.5% of patients with subclinical hypothyroidism progress to clinically overt hypothyroidism each year; the rate of progression is higher in patients with thyroid autoantibodies and higher thyroid stimulating hormone levels. However, thyroid function normalises spontaneously in up to 40% cases. Only a small minority of patients with subclinical hypothyroidism have symptoms, and the evidence to support that levothyroxine ameliorate the symptoms in these patients is weak. Subclinical hypothyroidism in younger patients (<65 years) is associated with an increased risk of coronary heart disease, heart failure and cerebrovascular disease. The risk increases with increasing levels of thyroid stimulating hormone, and is particularly high in patients with TSH levels ≥10.0 mu/L. There is lack of evidence from randomised controlled trials as to whether levothyroxine treatment can prevent these risks, although a large observational study of the UK general practice research database has shown that levothyroxine may reduce the risk of coronary heart disease in younger patients (<70 years). Therefore, the decision whether to treat or not to treat subclinical hypothyroidism should be made after careful consideration of the patient's age, the presence of symptoms, the presence of thyroid antibodies and other risk factors such as cardiovascular disease.