Type and extent of somatic morbidity before and after the diagnosis of hypothyroidism. a nationwide register study

Thyroid function and risk of type 2 diabetes: a population-based prospective cohort study

BACKGROUND

The association of thyroid function with risk of type 2 diabetes remains elusive. We aimed to investigate the association of thyroid function with incident diabetes and progression from prediabetes to diabetes in a population-based prospective cohort study.

METHODS

We included 8452 participants (mean age 65 years) with thyroid function measurement, defined by thyroid-stimulating hormone (TSH) and free thyroxine (FT4), and longitudinal assessment of diabetes incidence. Cox-models were used to investigate the association of TSH and FT4 with diabetes and progression from prediabetes to diabetes. Multivariable models were adjusted for age, sex, high-density lipoprotein cholesterol, and glucose at baseline, amongst others.

RESULTS

During a mean follow-up of 7.9 years, 798 diabetes cases occurred. Higher TSH levels were associated with a higher diabetes risk (hazard ratio [HR] 1.13; 95 % confidence interval [CI], 1.08-1.18, per logTSH), even within the reference range of thyroid function (HR 1.24; 95 % CI, 1.06-1.45). Higher FT4 levels were associated with a lower diabetes risk amongst all participants (HR 0.96; 95 % CI, 0.93-0.99, per 1 pmol/L) and in participants within the reference range of thyroid function (HR 0.96; 95 % CI, 0.92-0.99). The risk of progression from prediabetes to diabetes was higher with low-normal thyroid function (HR 1.32; 95 % CI, 1.06-1.64 for TSH and HR 0.91; 95 % CI, 0.86-0.97 for FT4). Absolute risk of developing diabetes type 2 in participants with prediabetes decreased from 35 % to almost 15 % with higher FT4 levels within the normal range.

CONCLUSIONS

Low and low-normal thyroid function are risk factors for incident diabetes, especially in individuals with prediabetes. Future studies should investigate whether screening for and treatment of (subclinical) hypothyroidism is beneficial in subjects at risk of developing diabetes.

Unemployment Risk and Decreased Income Two and Four Years After Thyroid Cancer Diagnosis: A Population-Based Study

BACKGROUND

Thyroid cancer (TC) often occurs in relatively young patients and has a high cure rate. However, decreased psychological and physical well-being may reduce the work capability of patients with TC. This study aimed to compare the risk for unemployment and decreased income in TC survivors with a matched non-cancer group at two and four years after diagnosis. The study also aimed to predict unemployment and income changes at two and four years after diagnosis.

METHODS

A historical prospective study design was used, with cohort inception and baseline measurements drawn from the Israeli Central Bureau of Statistics 1995 National Census, with follow-up until 2011. Cancer incidence was obtained from the Israel Cancer Registry, and employment status from the Tax Authority. A matched group was sampled from the census population. Binary logistic regression analyses were used to assess odds ratios (OR) for the study outcomes, controlled for age, sex, ethnicity, education years, socioeconomic position, and employment status at two years before diagnosis.

RESULTS

In total, 417 cases of TC and 1277 non-cancer matched subjects were included in the study. People who died during the study period were excluded. The mean age at the time of cancer diagnosis was 43.5 years in the TC group and 43.8 years in the control group (p = 0.6). After adjusting for potential confounders, a positive association was found between TC and risk of unemployment two years after diagnosis (OR = 1.46 [confidence interval (CI) 1.09-1.95]), and decreased income two years after diagnosis (OR = 1.61 [CI 1.23-2.01]) and four years after diagnosis (OR = 1.63 [CI 1.25-2.13]). The association between TC and unemployment at four years after diagnosis weakened and lost significance (OR = 1.30 [CI 0.98-1.72]).

CONCLUSIONS

TC survivorship was associated with unemployment at two years and decreased income at two and four years after diagnosis. Decreased income may be a marker for a shift to part-time work rather than a return to full-time work. The findings suggest that interventions to enhance the return to full-time work are needed in this population.

Disease-Specific as Well as Generic Quality of Life Is Widely Impacted in Autoimmune Hypothyroidism and Improves during the First Six Months of Levothyroxine Therapy

BACKGROUND

Hypothyroidism is often diagnosed, and subsequently treated, due to health-related quality of life (HRQL) issues. However, HRQL following treatment has never previously been assessed in longitudinal descriptive studies using validated instruments.

OBJECTIVE

To investigate disease-specific (ThyPRO) and generic (SF-36) HRQL, following levothyroxine therapy in patients with hypothyroidism due to autoimmune thyroiditis.

METHODS

This prospective cohort study was set at endocrine outpatient clinics at two Danish university hospitals. Seventy-eight consecutive patients were enrolled and completed HRQL questionnaires before, six weeks, and six months after initiation of levothyroxine therapy. Normative ThyPRO (n = 739) and SF-36 (n = 6,638) data were available for comparison and changes in HRQL following treatment were estimated and quantified.

RESULTS

Prior to treatment, all ThyPRO scales were significantly impacted (p<0.0001), compared to the general population sample. The same was observed for seven of eight SF-36 scales, the exception being Bodily Pain. Tiredness (ThyPRO) and Vitality (SF-36) were the most markedly impacted scales. After six weeks of treatment, nine of thirteen ThyPRO scales had significantly improved. ThyPRO improvements were consistent at six months, where five of eight SF-36 scales had also significantly improved, but deficits persisted for a subset of both ThyPRO and SF-36 scales.

CONCLUSIONS

In this population of hypothyroid patients, HRQL was widely affected before treatment, with tiredness as the cardinal impairment according to both ThyPRO and SF-36. Many aspects of HRQL improved during the first six months of LT4 therapy, but full recovery was not obtained. Our results may help clinicians inform patients about expected clinical treatment effects.

External validation of a normal tissue complication probability model for radiation-induced hypothyroidism in an independent cohort

BACKGROUND

A normal tissue complication probability (NTCP) model for radiation-induced hypothyroidism (RIHT) was previously derived in patients with squamous cell carcinoma of the head and neck (HNSCC) discerning thyroid volume (Vthyroid), mean thyroid dose (Dmean), and latency as predictive factors. The purpose of this study was to test the performance of this model in an independent cohort of patients receiving primary radiotherapy (RT) for HNSCC.

MATERIAL AND METHODS

A validation cohort of 198 patients with HNSCC was included after plasma thyrotropin (TSH) assessment. RIHT was defined as TSH > 4.0 mU/l from blood samples obtained during follow-up. A new mixture NTCP model was developed from the validation cohort after multivariable analysis. Due to only one follow-up TSH assessment in the validation cohort, the time factor derived from the original cohort was fixed in a mixture model and applied for the NTCP validation. Association between model predictions of the initial model and observed clinical outcome in the validation cohort was investigated by applying the previous model (Vthyroid, Dmean and time) on the new cohort and comparing it to the clinical outcome.

RESULTS

Both Dmean and Vthyroid were confirmed as significant risk factors for RIHT in the validation cohort, odds ratio (OR) 1.19 (1.1-1.37) and OR 0.75 (0.57-0.9), respectively. A small difference in overall probability of RIHT was observed between the cohorts, further analysis indicated this to be related to less frequent blood tests in the validation cohort relative to the original cohort. However, Pearson's correlation coefficients between model and clinical outcome were high: r = 0.97 estimated by the original model versus the original cohort, and r = 0.97 estimated by the original model versus the new cohort.

CONCLUSION

Dmean and Vthyroid were significant predictors of RIHT in both cohorts. The original NTCP model demonstrated external validity owing to high Pearson's correlation coefficients between estimated and observed incidence rates of RIHT in the original as well as in the validation cohort. This model may facilitate clinically relevant estimations of RIHT after RT to the neck.

Exploring the experiences of people with hypo- and hyperthyroidism

Thyroid diseases evoke a complex range of psychological and physical symptoms. The psychosocial aspects of living with diseases causing hypo- or hyperthyroidism are poorly understood. In this article, we report the findings of a qualitative interview study in which we explored the lived experiences of 16 people with hypo- or hyperthyroidism. We purposefully selected participants from Danish outpatient clinics according to their diagnosis (Hashimoto's thyroiditis or Graves' disease with or without orbitopathy), age (18 to 65 years), and duration of treatment (more than 6 months). We used interpretative phenomenological analysis (IPA) as a theoretical frame and analytical approach and identified three superordinate themes: losing control over mental and physical states, ambiguous signs of disease, and negotiating sickness. We discuss the findings in the context of the recent literature on chronic illness and argue that these themes play an important role in the conceptualization and management of thyroid diseases.

The excess risk of major osteoporotic fractures in hypothyroidism is driven by cumulative hyperthyroid as opposed to hypothyroid time: an observational register-based time-resolved cohort analysis

The long-term relationship between hypothyroidism and fracture risk is challenging to dissect because of the modifying influence of subsequent thyroxine replacement with the potential for excessive replacement doses. We studied changes in serum thyrotropin concentration (TSH) over time and association with fracture risk in real-world patients presenting with elevated TSH. All TSH determinations were done in the same laboratory, which served all hospitals and general practices. The study population consisted of all adults with a first measurement of TSH >4.0 mIU/L (n = 8414) or normal TSH (n = 222,138; comparator). We used a Cox proportional hazards analysis incorporating additional time-dependent covariates to represent initiation of thyroxine replacement and cumulative number of periods with high versus low TSH after index date with a mean follow-up of 7.2 years. Elevated baseline TSH was not associated with an increased risk of hip fracture (HR 0.90; 95% CI, 0.80 to 1.02) or major osteoporotic fractures (HR 0.97; 95% CI, 0.90 to 1.05), nor was subsequent thyroxine prescription predictive of increased risk of fractures. The number of subsequent 6-month periods with low TSH-suggesting excessive thyroxine dosing-was significantly associated with increased risk of both hip fracture (HR 1.09; 95% CI, 1.04 to 1.15) and major osteoporotic fracture (HR 1.10; 95% CI, 1.06 to 1.14). When gender- and age-stratified analyses for major osteoporotic fractures were undertaken, hyperthyroid time was identified as a predictor of fracture risk in postmenopausal women whereas hypothyroid time predicted increased fracture risk in men below age 75 years. In conclusion, among patients who present with an elevated TSH, the long-term risk of hip and other osteoporotic fractures is strongly related to the cumulative duration of periods with low TSH-likely from excessive replacement. An independent effect of elevated TSH could only be observed in young and middle-aged men, suggesting gender-discrepant consequences on risk.

Thyroid-specific questions on work ability showed known-groups validity among Danes with thyroid diseases

Purpose

We aimed to identify the best approach to work ability assessment in patients with thyroid disease by evaluating the factor structure, measurement equivalence, known-groups validity, and predictive validity of a broad set of work ability items.

Methods

Based on the literature and interviews with thyroid patients, 24 work ability items were selected from previous questionnaires, revised, or developed anew. Items were tested among 632 patients with thyroid disease (non-toxic goiter, toxic nodular goiter, Graves’ disease (with or without orbitopathy), autoimmune hypothyroidism, and other thyroid diseases), 391 of which had participated in a study 5 years previously. Responses to select items were compared to general population data. We used confirmatory factor analyses for categorical data, logistic regression analyses and tests of differential item function, and head-to-head comparisons of relative validity in distinguishing known groups.

Results

Although all work ability items loaded on a common factor, the optimal factor solution included five factors: role physical, role emotional, thyroid-specific limitations, work limitations (without disease attribution), and work performance. The scale on thyroid-specific limitations showed the most power in distinguishing clinical groups and time since diagnosis. A global single item proved useful for comparisons with the general population, and a thyroid-specific item predicted labor market exclusion within the next 5 years (OR 5.0, 95 % CI 2.7–9.1).

Conclusions

Items on work limitations with attribution to thyroid disease were most effective in detecting impact on work ability and showed good predictive validity. Generic work ability items remain useful for general population comparisons.

Hypothyroidism is a predictor of disability pension and loss of labor market income: a Danish register-based study

BACKGROUND

Hypothyroidism is associated with an increased somatic and psychiatric disease burden. Whether there are any socioeconomic consequences of hypothyroidism, such as early retirement or loss of income, remains unclarified.

AIM

Our aim was to examine, compared with a matched control group, the risk of receiving disability pension (before the age of 60) and the effect on labor market income in patients diagnosed with hypothyroidism.

METHODS

This was an observational register-based cohort study. By record linkage between different Danish health registers, 1745 hypothyroid singletons diagnosed before the age of 60 were each matched with 4 non-hypothyroid controls and followed for a mean of 5 (range 1-31) years. Additionally, we included 277 same-sex twin pairs discordant for hypothyroidism. The risk of disability pension was evaluated by the Cox regression analysis. Changes in labor market income progression over 5 years were evaluated using a difference in difference model.

RESULTS

With a hazard ratio of 2.24 (95% confidence interval = 1.73-2.89), individuals diagnosed with hypothyroidism had a significantly increased risk of disability pension. This remained significant when adjusting for educational level and comorbidity (hazard ratio = 1.89; 95% confidence interval = 1.42-2.51). In an analysis of labor market income, 2 years before compared with 2 years after the diagnosis of hypothyroidism, the hypothyroid individuals had on average a €1605 poorer increase than their euthyroid controls (P < .001). Essentially similar results were found in the twin population.

CONCLUSION

A diagnosis of hypothyroidism before the age of 60 is associated with loss of labor market income and an 89% increased risk of receiving a disability pension.

Increased risk of long-term sickness absence, lower rate of return to work, and higher risk of unemployment and disability pensioning for thyroid patients: a Danish register-based cohort study

CONTEXT

Little is known about how thyroid diseases affect work ability.

OBJECTIVE

The objective of this study was to evaluate the risk of work disability for patients with thyroid disease compared with the general population.

DESIGN, SETTING, AND PARTICIPANTS

In a longitudinal register study, outpatients (n = 862) with nontoxic goiter, hyperthyroidism, Graves' orbitopathy (GO), autoimmune hypothyroidism, or other thyroid diseases and their matched controls (n = 7043) were observed in the years 1994-2011 in Danish national registers of social benefits, health, and work characteristics. Cox regression analyses estimated adjusted hazard ratios (HRs) for the first year after diagnosis and subsequent years.

MAIN OUTCOME MEASURES

Transitions between work, long-term sickness absence, unemployment, and disability pension were measured.

RESULTS

Patients differed significantly from the general population with regard to sickness absence, disability pension, return from sickness absence, and unemployment. In the first year after diagnosis, higher risks of sickness absence was seen for GO (HR 6.94) and other hyperthyroid patients (HR 2.08), who also had lower probability of returning from sickness absence (HR 0.62) and higher risk of disability pension (HR 4.15). Patients with autoimmune hypothyroidism showed a lower probability of returning from sickness absence (HR 0.62). In subsequent years, GO patients had significantly higher risk of sickness absence (HR 2.08), lower probability of return from sickness absence (HR 0.51), and unemployment (HR 0.52) and a higher risk of disability pension (HR 4.40). Hyperthyroid patients also had difficulties returning from sickness absence (HR 0.71).

CONCLUSIONS

Thyroid patients' risk of work disability is most pronounced in the first year after diagnosis and attenuates in subsequent years. GO patients have the highest risk of work disability.

Increased psychiatric morbidity before and after the diagnosis of hypothyroidism: a nationwide register study

BACKGROUND

Thyroid hormones are necessary for fetal brain development, and hypothyroidism in adults has been associated with mood symptoms and reduced quality of life. Nevertheless, our knowledge regarding the association and temporal relation between hypothyroidism and mental disorders is ambiguous. Our objective was to investigate, at a nationwide level, whether a diagnosis of hypothyroidism is associated with psychiatric morbidity.

METHODS

This is an observational cohort study. On the basis of record linkage between different Danish health registers, 2822 hypothyroid singletons each matched with 4 nonhypothyroid controls were identified and followed over a mean period of 6 years (range 1-13). Additionally, we included 385 same-sex twin pairs discordant for hypothyroidism. Diagnoses of psychiatric disorders as well as treatment with antidepressants, antipsychotics, and anxiolytics were recorded. Logistic and cox regression models were used to assess the risk of psychiatric morbidity before and after the diagnosis of hypothyroidism, respectively.

RESULTS

Before the diagnosis of hypothyroidism, such individuals had an increased prevalence of diagnoses with psychiatric disorders (odds ratio, OR, 1.51; 95% confidence interval [CI 1.12-2.04]) and increased prevalence of treatment with antipsychotics (OR 1.49 [CI 1.29-1.73]), antidepressants (OR 1.50 [CI 1.35-1.67]), and anxiolytics (OR 1.28 [CI 1.16-1.41]). After the diagnosis of hypothyroidism, patients had a higher risk of being diagnosed with a psychiatric disorder (hazard ratio, HR, 2.40 [CI 1.81-3.18]), and an increased risk of being treated with antidepressants (HR 1.30 [CI 1.15-1.47]) and anxiolytics (HR 1.27 [CI 1.10-1.47]), but not antipsychotics (HR 1.13 [CI 0.91-1.41]). On the basis of the twin data, we could not demonstrate genetic confounding.

CONCLUSIONS

Subjects with hypothyroidism have an increased risk of being diagnosed with a psychiatric disorder as well as being treated with antidepressants, antipsychotics, and anxiolytics both before and after the diagnosis of hypothyroidism.

The chronic autoimmune thyroiditis quality of life selenium trial (CATALYST): study protocol for a randomized controlled trial

BACKGROUND

Patients with chronic autoimmune thyroiditis have impaired health-related quality of life. The thyroid gland has a high selenium concentration, and specific selenoprotein enzyme families are crucial to immune function, and catalyze thyroid hormone metabolism and redox processes in thyroid cells. Previous randomized controlled trials have found that selenium supplementation decreases thyroid-disease-specific antibody levels. We hypothesize that selenium might be beneficial in the treatment of chronic autoimmune thyroiditis.

METHODS/DESIGN

The CATALYST trial is an investigator-initiated randomized, blinded, multicentre clinical trial of selenium supplementation versus placebo in patients with chronic autoimmune thyroiditis.

INCLUSION CRITERIA

age ≥18 years; serum thyroid peroxidase antibody level ≥100 IU/ml within the previous 12 months; treatment with levothyroxine and written informed consent.

EXCLUSION CRITERIA

previous diagnosis of toxic nodular goitre, Graves' hyperthyroidism, postpartum thyroiditis, Graves' orbitopathy; previous antithyroid drug treatment, radioiodine therapy or thyroid surgery; immune-modulatory or other medication affecting thyroid function; pregnancy, planned pregnancy or breastfeeding; allergy towards any intervention or placebo component; intake of selenium supplementation >55 μg/day; inability to read or understand Danish or lack of informed consent. The trial will include 2 × 236 participants. The experimental intervention and control groups will receive 200 μg selenium-enriched yeast or matching placebo tablets daily for 12 months. The experimental supplement will be SelenoPrecise®. The primary outcome is thyroid-related quality of life assessed by the Thyroid Patient-Reported Outcome (ThyPRO) questionnaire. Secondary outcomes include serum thyroid peroxidase antibody concentration; serum triiodothyronine/thyroxine ratio; levothyroxine dosage; adverse reactions and serious adverse reactions and events.

DISCUSSION

In this pragmatic trial, participating patients follow their usual treatment at their usual hospitals. In order to collect high-quality data on the clinical course and quality of life, and to minimize missing data, an elaborate trial management system has been designed. 12 months intervention duration was selected in consideration of the primary outcome, thyroid-related quality of life.

TRIAL REGISTRATION

ClinicalTrials.gov ID: NCT02013479.

Hyperthyroidism and psychiatric morbidity: evidence from a Danish nationwide register study

OBJECTIVE

Thyroid hormones are essential for the normal development of the fetal brain, while hyperthyroidism in adults is associated with mood symptoms and reduced quality of life. In this study, we aimed to investigate the association and temporal relationship between hyperthyroidism and psychiatric morbidity.

DESIGN

Register-based nationwide cohort study.

METHOD

Data on hyperthyroidism and psychiatric morbidity were obtained by record linkage of the Danish National Patient Registry and the Danish National Prescription Registry. A total of 2631 hyperthyroid individuals were identified and matched 1:4 with non-hyperthyroid controls and followed for a mean duration of 6 years (range 0-13). Logistic and Cox regression models were used to assess the risk of psychiatric morbidity before and after the diagnosis of hyperthyroidism respectively.

RESULTS

BEFORE THE DIAGNOSIS OF HYPERTHYROIDISM, SUCH INDIVIDUALS HAD AN INCREASED RISK OF BEING HOSPITALIZED WITH PSYCHIATRIC DIAGNOSES (ODDS RATIO (OR): 1.33; 95% CI: 0.98-1.80) and an increased risk of being treated with antipsychotics (OR: 1.17; 95% CI: 1.00-1.38), antidepressants (OR: 1.13; 95% CI: 1.01-1.27), or anxiolytics (OR: 1.28; 95% CI: 1.16-1.42). After the diagnosis of hyperthyroidism, there was a higher risk of being hospitalized with psychiatric diagnoses (hazard ratio (HR): 1.51; 95% CI: 1.11-2.05) and an increased risk of being treated with antipsychotics (HR: 1.46; 95% CI: 1.20-1.79), antidepressants (HR: 1.54; 95% CI: 1.36-1.74), or anxiolytics (HR: 1.47; 95% CI: 1.27-1.69).

CONCLUSIONS

Hyperthyroid individuals have an increased risk of being hospitalized with psychiatric diagnoses and being treated with antipsychotics, antidepressants, and anxiolytics, both before and after the diagnosis of hyperthyroidism.