The Relation Between Thyroid Function and Anemia: A Pooled Analysis of Individual Participant Data

Abstract Context Anemia and thyroid dysfunction often co-occur, and both increase with age. Human data on relationships between thyroid disease and anemia are scarce. Objective To investigate the cross-sectional and longitudinal associations between clinical thyroid status and anemia. Design Individual participant data meta-analysis. Setting Sixteen cohorts participating in the Thyroid Studies Collaboration (n = 42,162). Main Outcome Measures Primary outcome measure was anemia (hemoglobin <130 g/L in men and <120 g/L in women). Results Cross-sectionally, participants with abnormal thyroid status had an increased risk of having anemia compared with euthyroid participants [overt hypothyroidism, pooled OR 1.84 (95% CI 1.35 to 2.50), subclinical hypothyroidism 1.21 (1.02 to 1.43), subclinical hyperthyroidism 1.27 (1.03 to 1.57), and overt hyperthyroidism 1.69 (1.00 to 2.87)]. Hemoglobin levels were lower in all groups compared with participants with euthyroidism. In the longitudinal analyses (n = 25,466 from 14 cohorts), the pooled hazard ratio for the risk of development of anemia was 1.38 (95% CI 0.86 to 2.20) for overt hypothyroidism, 1.18 (1.00 to 1.38) for subclinical hypothyroidism, 1.15 (0.94 to 1.42) for subclinical hyperthyroidism, and 1.47 (0.91 to 2.38) for overt hyperthyroidism. Sensitivity analyses excluding thyroid medication or high levels of C-reactive protein yielded similar results. No differences in mean annual change in hemoglobin levels were observed between the thyroid hormone status groups. Conclusion Higher odds of having anemia were observed in participants with both hypothyroid function and hyperthyroid function. In addition, reduced thyroid function at baseline showed a trend of increased risk of developing anemia during follow-up. It remains to be assessed in a randomized controlled trial whether treatment is effective in reducing anemia.

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Association between ultrasonography echogenicity and heterogeneity and thyroid function in autoimmune diffuse thyroid diseases in children and adolescents

10.21203/rs.3.rs-557677/v1 ◽

2021 ◽

Author(s):

Ji Eun Park ◽

Sook Min Hwang ◽

Ji-Young Hwang ◽

Jin Hee Moon ◽

Ik Yang ◽

...

Keyword(s):

Thyroid Function ◽

Thyroid Dysfunction ◽

Thyroid Stimulating Hormone ◽

Thyroid Diseases ◽

Overt Hypothyroidism ◽

Thyroid Ultrasound ◽

Thyroid Status ◽

Children And Adolescent ◽

Overt Hyperthyroidism

Abstract Purpose: To evaluate the association between thyroid echogenicity and heterogeneity seen on ultrasonography (US) and thyroid function in pediatric and adolescent populations with autoimmune diffuse thyroid diseases (AITD).Methods: From 2000 to 2020, we reviewed thyroid ultrasound (US) images and thyroid function statuses in 133 children and adolescent AITD patients. Our review of the images focused on decreased echogenicity and heterogeneity, which were classified into four grades.Results: Among patients with overt hypothyroidism or overt hyperthyroidism, 94.2% (65/69) showed a US grade of 3 or 4. In patients with subclinical hyper/hypothyroidism or euthyroidism, 45.3% (29/64) showed grades 1 or 2. There were no overt hyper/hypothyroidism patients with US grade 1. When we compared US grades according to thyroid status, more severe thyroid dysfunction was significantly associated with higher US grade (p=0.047). Thyroid stimulating hormone (TSH) level differed significantly according to US grades when we evaluated hyperthyroid (p=0.035) and hypothyroid (p=0.027) states independently. 11 patients showed both US grade and thyroid function status changes on follow-up US.Conclusions: In children and adolescent AITD patients, there was an association between decreased echogenicity and heterogeneity on US and thyroid dysfunction.

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Thyroid Function in 3000 Cases of Patients With Atrial Fibrillation Treated With Catheter Ablation

Journal of the Endocrine Society ◽

10.1210/jendso/bvab048.2003 ◽

2021 ◽

Vol 5 (Supplement_1) ◽

pp. A979-A980

Author(s):

Sayaka Yamada ◽

Yasuyo Nakajima ◽

Ayaka Nishikido ◽

Masako Akuzawa ◽

Koji Sakamaki ◽

...

Keyword(s):

Atrial Fibrillation ◽

Catheter Ablation ◽

Thyroid Hormones ◽

Thyroid Function ◽

Subclinical Hypothyroidism ◽

Treated Group ◽

Control Group ◽

Subclinical Hyperthyroidism ◽

Treated Male ◽

Overt Hyperthyroidism

Abstract Objective: Thyroid hormones have various effects on cardiac and circulatory systems, leading to arrhythmias and heart failure. In Europe and the United States, it has been reported that elevated thyroid hormones within the normal range have been reported to be associated with a risk of atrial fibrillation, however, there was no report on Japanese cases, a country that differs in iodine intake and ethnicity from the West. Therefore, we evaluated the abnormality of thyroid function in a large number of cases of atrial fibrillation (AF) who received catheter ablation (RFCA) in Japan. Methods: We evaluated 2,937 cases of atrial fibrillation (2,084 males, mean age 64.1±10.7 years and 853 females, 69.0±8.5 years) who underwent RFCA at the Gunma Prefectural Cardiovascular Center between 2012 and 2018. As a control we used a total of 15,660 participants for health check-up (9,176 males, mean age 49.7±9.8 years and 6,484 females, 48.9±10.3 years) from 2006 to 2013, and we evaluated thyroid function after adjusting for gender-specific age. Results: The prevalence of overt hyperthyroidism was significantly higher in the RFCA-treated male group (0.43%) than in the control group (0.07%), even after adjusting for age (p<0.01). Similarly, the prevalence of subclinical hyperthyroidism was also significantly higher in the RFCA-treated male group (3.12%) than in the control group (0.94%) after adjusting for age (p<0.01). On the other hand, subclinical hypothyroidism was significantly lower in the RFCA-treated group after adjusting for age (2.97% in the RFCA-treated group and 3.93% in the control group, p<0.01). Females showed the same results as males. Conclusions: In an iodine rich country Japan, not only overt hyperthyroidism but also subclinical hyperthyroidism is an obvious risk factor for severe atrial fibrillation in Japan. Intriguingly, subclinical hypothyroidism might contribute to the prevention of atrial fibrillation, suggesting that slightly higher serum TSH levels might be better for elderlies.

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Isfahan Thyroid Cohort Study (ITCS)

Archives of Iranian Medicine ◽

10.34172/aim.2021.118 ◽

2021 ◽

Vol 24 (11) ◽

pp. 788-795

Author(s):

Samaneh Shahrokh Esfahani ◽

Aliye Tabatabaee ◽

Ashraf Aminorroaya ◽

Masoud Amini ◽

Awat Feizi ◽

...

Keyword(s):

Cohort Study ◽

Subclinical Hypothyroidism ◽

Epidemiological Studies ◽

Overt Hypothyroidism ◽

Cluster Sampling ◽

Thyroid Peroxidase ◽

Second Phase ◽

Thyroid Disorders ◽

Subclinical Hyperthyroidism ◽

Overt Hyperthyroidism

Background: The Isfahan Thyroid Cohort Study (ITCS) is one of the few population-based epidemiological studies in Iran that investigates the prevalence and incidence of thyroid disorders including hypothyroidism, hyperthyroidism, goiter, nodule, and iodine status. Methods: This cohort is located in Isfahan, Iran. The first phase was initiated in 2006 with 2523 participants (1275 males, 1248 females). The participants were selected using multi-stage cluster sampling from the general residents of Isfahan, Iran. The study had two phases (2006 and 2011) and its third stage is planned for 2020–2021. Results: The prevalence of thyroid function states was euthyroid (89.3%, 95% CI: 88%–90%), overt hypothyroidism (2.8%, 95% CI: 2%‒3%), subclinical hypothyroidism (5.8%, 95% CI: 4%–6%), overt hyperthyroidism (0.8%, 95% CI: 0.4%‒1%), and subclinical hyperthyroidism (0.99%, 95% CI: 0.6%–1%). Hypothyroidism and hyperthyroidism were significantly associated with goiter. The incidence of thyroid dysfunction was reported as follows: overt hypothyroidism (2.7, 95% CI: 1.6–3.7), subclinical hypothyroidism (20.6, 95% CI: 18–23), overt hyperthyroidism (1.9, 95% CI: 1–2.7) and subclinical hyperthyroidism (2.7, 95% CI: 1.6–3.7) per 1000 (person-year). Conclusion: We assessed the prevalence and incidence of thyroid disorders in Isfahan in the first and second phase, respectively. We are conducting the third phase of the ITCS in order to study the associations between thyroid peroxidase antibody (TPOAb) level and environmental factors such as infection.

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Thyroid Dysfunction States and Incident Cardiovascular Events: The Tehran Thyroid Study

Hormone and Metabolic Research ◽

10.1055/s-0043-121031 ◽

2017 ◽

Vol 50 (01) ◽

pp. 37-43 ◽

Cited By ~ 6

Author(s):

Maryam Tohidi ◽

Arash Derakhshan ◽

Samaneh Akbarpour ◽

Atieh Amouzegar ◽

Ladan Mehran ◽

...

Keyword(s):

Thyroid Function ◽

Subclinical Hypothyroidism ◽

Thyroid Dysfunction ◽

Middle Eastern ◽

Thyroid Stimulating Hormone ◽

Overt Hypothyroidism ◽

Subclinical Hyperthyroidism ◽

Significant Difference ◽

Middle Eastern Population

AbstractThe objective of the study was to investigate the relation of different thyroid function states with the incidence of cardiovascular disease (CVD)/coronary heart disease (CHD) among a Middle-Eastern population with a high incidence of CVD/CHD. A total of 3975 participants entered the study (43.6% men). According to their thyroid stimulating hormone (TSH) and free thyroxin (FT4) levels, the participants were categorized into 5 groups: euthyroid, subclinical hypothyroidism, overt hypothyroidism, subclinical hyperthyroidism, and overt hyperthyroidism. Multivariable Cox proportional hazard models were used to assess the relation of different thyroid function states with incident CVD/CHD, with euthyroid state as reference. The mean age (SD) of the participants was 46.5 (12.0) years. At baseline, no significant difference was observed in the frequency of prevalent CVD cases (n=201) between all groups. No significant interaction was found between prevalent CVD and different thyroid function states with outcomes, hence, we did not exclude participants with prevalent CVD from data analysis. A total of 400 CVD events (358 CHD cases) during a median follow-up of 11.2 years (inter-quartile range: 1.96) occurred. During the follow-up, even in the age and sex adjusted model, no association was observed between different states of thyroid dysfunction and incidence of CVD/CHD. The multivariable hazard ratios (95% CI) of subclinical hypothyroidism, hypothyroidism, subclinical hyperthyroidism, and hyperthyroidism for CVD events were 1.21 (0.77–1.88), 0.76 (0.33–1.69), 0.81 (0.46–1.41) and 1.48 (0.70–3.16), respectively. Both at baseline and during follow-up, no relation was observed between different states of thyroid function with prevalence and incidence of CVD/CHD.

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Association between Sleep Duration and Subclinical Thyroid Dysfunction Based on Nationally Representative Data

Journal of Clinical Medicine ◽

10.3390/jcm8112010 ◽

2019 ◽

Vol 8 (11) ◽

pp. 2010 ◽

Cited By ~ 1

Author(s):

Woojun Kim ◽

Jeongmin Lee ◽

Jeonghoon Ha ◽

Kwanghoon Jo ◽

Dong-Jun Lim ◽

...

Keyword(s):

Sleep Duration ◽

Thyroid Function ◽

Subclinical Hypothyroidism ◽

Thyroid Dysfunction ◽

Multiple Logistic Regression Analysis ◽

Subclinical Hyperthyroidism ◽

Free T4 ◽

Representative Data ◽

Increased Risk ◽

The Impact

Background: Sleep duration is an identified risk factor for adverse health outcomes. As the endocrine system is closely intertwined with sleep duration and quality, the association between endocrine dysfunction and sleep has been evaluated. Thyroid function, particularly that related to thyrotropin (TSH), is also known to be influenced by the sleep/awake status and circadian rhythm. Additionally, a link between sleep duration and autoimmunity, which is a common cause of thyroid dysfunction, has been suggested; however, depending on the sleep deprivation method used in studies, the effects of sleep on thyroid function vary. The relationship between subclinical thyroid dysfunction and sleep duration is poorly documented. Thus, to elucidate the impact of sleep on thyroid function, we investigated the association of subclinical thyroid dysfunction with sleep duration using representative data from the sixth Korea National Health and Nutrition Examination Survey, conducted from 2013 to 2015. Methods: In all, 4945 participants (2543 male and 2402 female) were included after excluding subjects using the following criteria: <19 years of age, free T4 level outside the normal range, history of thyroid disease, or incomplete data. The population was classified into three groups: short sleeper (<7 h/day), normal sleeper (7–8 h/day), and long sleeper (>8 h/day). The odds ratio (OR) for subclinical hypothyroidism or hyperthyroidism according to sleep duration was evaluated. Results: The short, normal, and long sleeper groups consisted of 2097, 2514, and 334 subjects, respectively. On multiple logistic regression analysis, compared to normal sleepers, short sleepers showed a significantly increased risk of subclinical hyperthyroidism (OR 1.37, 95% confidential interval (CI) 1.02–1.84, p = 0.036), while the risk of subclinical hypothyroidism in short sleepers was not elevated. Comparing long sleepers to normal sleepers, the OR for subclinical hyperthyroidism and hypothyroidism was 1.79 (95% CI 1.12–2.86, p = 0.015) and 1.91 (95% CI 1.03–3.53, p = 0.039), respectively. Conclusions: Both shorter and longer sleep durations were associated with an increase in the risk of subclinical thyroid dysfunction compared to the optimal sleep duration. This analysis of representative population data shows that sleep duration could intertwine with thyroid function resulting in increased risk of subclinical thyroid dysfunction.

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Thyroid Function Tests in the Reference Range and Fracture: Individual Participant Analysis of Prospective Cohorts

The Journal of Clinical Endocrinology & Metabolism ◽

10.1210/jc.2017-00294 ◽

2017 ◽

Vol 102 (8) ◽

pp. 2719-2728 ◽

Cited By ~ 16

Author(s):

Carole E Aubert ◽

Carmen Floriani ◽

Douglas C Bauer ◽

Bruno R da Costa ◽

Daniel Segna ◽

...

Keyword(s):

Hip Fracture ◽

Standard Deviation ◽

Fracture Risk ◽

Thyroid Function ◽

Sensitivity Analyses ◽

Thyroid Function Tests ◽

Standard Deviation Increase ◽

Function Tests ◽

Increased Risk ◽

Individual Participant

Abstract Context Hyperthyroidism is associated with increased fracture risk, but it is not clear if lower thyroid-stimulating hormone (TSH) and higher free thyroxine (FT4) in euthyroid individuals are associated with fracture risk. Objective To evaluate the association of TSH and FT4 with incident fractures in euthyroid individuals. Design Individual participant data analysis. Setting Thirteen prospective cohort studies with baseline examinations between 1981 and 2002. Participants Adults with baseline TSH 0.45 to 4.49 mIU/L. Main Outcome Measures Primary outcome was incident hip fracture. Secondary outcomes were any, nonvertebral, and vertebral fractures. Results were presented as hazard ratios (HRs) with 95% confidence interval (CI) adjusted for age and sex. For clinical relevance, we studied TSH according to five categories: 0.45 to 0.99 mIU/L; 1.00 to 1.49 mIU/L; 1.50 to 2.49 mIU/L; 2.50 to 3.49 mIU/L; and 3.50 to 4.49 mIU/L (reference). FT4 was assessed as study-specific standard deviation increase, because assays varied between cohorts. Results During 659,059 person-years, 2,565 out of 56,835 participants had hip fracture (4.5%; 12 studies with data on hip fracture). The pooled adjusted HR (95% CI) for hip fracture was 1.25 (1.05 to 1.49) for TSH 0.45 to 0.99 mIU/L, 1.19 (1.01 to 1.41) for TSH 1.00 to 1.49 mIU/L, 1.09 (0.93 to 1.28) for TSH 1.50 to 2.49 mIU/L, and 1.12 (0.94 to 1.33) for TSH 2.50 to 3.49 mIU/L (P for trend = 0.004). Hip fracture was also associated with FT4 [HR (95% CI) 1.22 (1.11 to 1.35) per one standard deviation increase in FT4]. FT4 only was associated with any and nonvertebral fractures. Results remained similar in sensitivity analyses. Conclusions Among euthyroid adults, lower TSH and higher FT4 are associated with an increased risk of hip fracture. These findings may help refine the definition of optimal ranges of thyroid function tests.

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An individual participant data analysis of prospective cohort studies on the association between subclinical thyroid dysfunction and depressive symptoms

Scientific Reports ◽

10.1038/s41598-020-75776-1 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Lea Wildisen ◽

Cinzia Del Giovane ◽

Elisavet Moutzouri ◽

Shanthi Beglinger ◽

Lamprini Syrogiannouli ◽

...

Keyword(s):

Systematic Review ◽

Depressive Symptoms ◽

Subclinical Hypothyroidism ◽

Thyroid Dysfunction ◽

Individual Participant Data ◽

Subclinical Hyperthyroidism ◽

Prospective Cohort Studies ◽

Individual Participant ◽

Prospective Cohorts

Abstract In subclinical hypothyroidism, the presence of depressive symptoms is often a reason for starting levothyroxine treatment. However, data are conflicting on the association between subclinical thyroid dysfunction and depressive symptoms. We aimed to examine the association between subclinical thyroid dysfunction and depressive symptoms in all prospective cohorts with relevant data available. We performed a systematic review of the literature from Medline, Embase, Cumulative Index to Nursing and Allied Health Literature, and the Cochrane Library from inception to 10th May 2019. We included prospective cohorts with data on thyroid status at baseline and depressive symptoms during follow-up. The primary outcome was depressive symptoms measured at first available follow-up, expressed on the Beck’s Depression Inventory (BDI) scale (range 0–63, higher values indicate more depressive symptoms, minimal clinically important difference: 5 points). We performed a two-stage individual participant data (IPD) analysis comparing participants with subclinical hypo- or hyperthyroidism versus euthyroidism, adjusting for depressive symptoms at baseline, age, sex, education, and income (PROSPERO CRD42018091627). Six cohorts met the inclusion criteria, with IPD on 23,038 participants. Their mean age was 60 years, 65% were female, 21,025 were euthyroid, 1342 had subclinical hypothyroidism and 671 subclinical hyperthyroidism. At first available follow-up [mean 8.2 (± 4.3) years], BDI scores did not differ between participants with subclinical hypothyroidism (mean difference = 0.29, 95% confidence interval = − 0.17 to 0.76, I2 = 15.6) or subclinical hyperthyroidism (− 0.10, 95% confidence interval = − 0.67 to 0.48, I2 = 3.2) compared to euthyroidism. This systematic review and IPD analysis of six prospective cohort studies found no clinically relevant association between subclinical thyroid dysfunction at baseline and depressive symptoms during follow-up. The results were robust in all sensitivity and subgroup analyses. Our results are in contrast with the traditional notion that subclinical thyroid dysfunction, and subclinical hypothyroidism in particular, is associated with depressive symptoms. Consequently, our results do not support the practice of prescribing levothyroxine in patients with subclinical hypothyroidism to reduce the risk of developing depressive symptoms.

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The Relationship Between Thyroid Function and Metabolic Syndrome and Its Components: A Cross-Sectional Study in a Chinese Population

Frontiers in Endocrinology ◽

10.3389/fendo.2021.661160 ◽

2021 ◽

Vol 12 ◽

Author(s):

Jiaji He ◽

Yaxin Lai ◽

Jing Yang ◽

Yongli Yao ◽

Yongze Li ◽

...

Keyword(s):

Metabolic Syndrome ◽

Waist Circumference ◽

Thyroid Function ◽

Subclinical Hypothyroidism ◽

Chinese Population ◽

Overt Hypothyroidism ◽

Iodine Nutrition ◽

Cross Sectional ◽

The Relationship ◽

Overt Hyperthyroidism

ObjectiveThe present study examined the relationship between thyroid function status and the prevalence of metabolic syndrome in a Chinese population.MethodsCross-sectional data were obtained from the Thyroid Disease, Iodine Nutrition and Diabetes Epidemiology (TIDE) Survey. A total of 62,408 subjects aged ≥18 years were enrolled. Differences in metabolic indicators and the prevalence of metabolic syndrome according to sex and thyroid function status were compared. Logistic regression was used to analyze the influence of thyroid function on metabolic syndrome and its components.ResultsThe prevalence of metabolic syndrome was generally higher in men than women. Overt hyperthyroidism and subclinical hypothyroidism had a significant effect on metabolism in men. Body mass index (BMI), waist circumference, and triglycerides (TGs) were significantly lower in men in the overt hyperthyroidism group, and BMI, waist circumference, systolic blood pressure (SBP) and TGs were higher in men in the subclinical hypothyroidism group than men in the normal group. Overt and subclinical hypothyroidism had significant impacts on metabolic components in women. BMI, waist circumference, TGs, SBP and DBP in the subclinical and overt hypothyroidism groups were significantly higher than the euthyroid group in women. The relative risk of abdominal obesity and hypertriglyceridemia was increased in women with hypothyroidism. Thyroid dysfunction had different effects on metabolic syndrome and its components before and after menopause.ConclusionThyroid function had important effects on the prevalence of metabolic syndrome. Women with hypothyroidism, especially post-menopausal women, had a higher risk of metabolic syndrome than men.

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Thyroid Dysfunction in Patients with Metabolic Syndrome: A Cross-Sectional, Epidemiological, Pan-India Study

International Journal of Endocrinology ◽

10.1155/2018/2930251 ◽

2018 ◽

Vol 2018 ◽

pp. 1-6 ◽

Cited By ~ 6

Author(s):

Vaishali Deshmukh ◽

Faraz Farishta ◽

Milind Bhole

Keyword(s):

Blood Pressure ◽

Metabolic Syndrome ◽

Subclinical Hypothyroidism ◽

Thyroid Dysfunction ◽

Overt Hypothyroidism ◽

Subclinical Hyperthyroidism ◽

Cross Sectional ◽

Fasting Plasma ◽

Indian Patients ◽

Overt Hyperthyroidism

Background. This study was conducted to assess the prevalence and clinical and epidemiological factors of thyroid dysfunction (TD) in Indian patients diagnosed with metabolic syndrome (MetS). Methods. In this cross-sectional study, 432 adults with an established diagnosis of MetS were enrolled across ten centers in India. Anthropometric measurements and vital signs were noted. Blood samples were tested for hemogram, coagulogram, lipid profile, and thyroid function. Fasting plasma glucose (FPG) and fasting plasma insulin were used for the calculation of homeostasis model assessment-estimated insulin resistance (HOMA-IR). Overt hypothyroidism was defined as thyroid-stimulating hormone TSH>4.50 μIU/mL with free thyroxine FT4<0.8 ng/dL and free triiodothyronine FT3<1.4 pg/mL; subclinical hypothyroidism as TSH>4.50 μIU/mL with FT4=0.8-1.8 ng/dL and FT3=1.4-4.4 pg/mL; overt hyperthyroidism as TSH<0.45 μIU/mL with FT4>1.8 ng/dL and FT3>4.4 pg/mL; and subclinical hyperthyroidism as TSH<0.45 μIU/mL with FT4=0.8-1.8 ng/dL and FT3=1.4-4.4 pg/mL. Results. About 121 out of 432 patients (28%) were diagnosed with TD (mean age±SD: 47.9±10.96 years), with women predominance (75% versus 25%). Most patients were in the >45 years of age group (men: 63%; women: 59%). TD was associated with high waist circumference (99.17%), reduced high-density lipoprotein-C (87.60%), raised HOMA-IR (86.78%), systolic blood pressure (77.69%), diastolic blood pressure (59.50%), fasting glucose (58.68%), and triglycerides (33.06%). Overt hypothyroidism was reported in 17.59% (N=76) of patients. Subclinical hypothyroidism, overt hypothyroidism, and subclinical hyperthyroidism were reported in 8.10%, 1.60%, and 0.70% patients with newly occurred TD, respectively. No case of overt hyperthyroidism was present in these patients. Conclusion. Hypothyroidism was the most common TD in Indian patients with MetS. A large proportion of TD cases diagnosed during the study highlight the need for vigilant thyroid screening in patients with MetS in a real-life setting.

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Subclinical Thyroid Function and Cardiovascular Events in patients with Atrial Fibrillation

Acta Endocrinologica ◽

10.1530/eje-20-1442 ◽

2021 ◽

Author(s):

Elisavet Moutzouri ◽

Christina Lyko ◽

Martin Feller ◽

Manuel Raphael Blum ◽

Luise Adam ◽

...

Keyword(s):

Atrial Fibrillation ◽

Subclinical Hypothyroidism ◽

Thyroid Dysfunction ◽

Total Mortality ◽

Composite Endpoint ◽

Community Dwelling ◽

Sensitivity Analyses ◽

Subclinical Hyperthyroidism ◽

Increased Risk ◽

Multivariable Adjustment

Objective: To evaluate if subclinical thyroid dysfunction is associated with cardiovascular (CV) risk in patients with atrial fibrillation (AF). Methods: Swiss-AF is a prospective cohort of community-dwelling participants aged ≥ 65 years with AF. Primary outcome was a composite endpoint of CV events (myocardial infarctions, stroke/transitory ischemic events, systemic embolism, heart failure (HF) hospitalizations, CV deaths). Secondary outcomes were component endpoints, total mortality and AF-progression. Exposures were thyroid dysfunction categories, TSH and fT4. Sensitivity analyses were performed for amiodarone use, thyroid hormones use and competing events. Results: 2415 patients were included (mean age 73.2 years; 27% women). 196 (8.4%) had subclinical hypothyroidism and 53 (2.3%) subclinical hyperthyroidism. Subclinical thyroid dysfunction was not associated with CV events, during a median follow-up of 2.1 years (max 5 years): age- and sex- adjusted hazard ratio (adjHR) of 0.99 (95% confidence interval (CI) 0.69-1.41) for subclinical hypothyroidism; and 0.55 (95%CI 0.23-1.32) for subclinical hyperthyroidism. Results remained robust following multivariable adjustment and sensitivity analyses. In euthyroid patients, fT4 levels were associated with an increased risk for the composite endpoint and HF (adjHR 1.46 95%CI 1.04- 2.05; adjHR 1.70 95%CI 1.08-2.66, respectively, for the highest quintile versus the middle quintile). Results remained similar following multivariable adjustment. Results remained significant for HF in sensitivity analyses. No association between subclinical thyroid dysfunction and total mortality or AF-progression was found. Conclusions: Subclinical hypothyroidism was not associated with increased CV risk in AF patients. Higher levels of fT4 with normal TSH were associated with higher risk for HF.

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