INTRODUCTION: Thyroid specialists influence how hypothyroid patients are treated, including patients managed in primary care. Given that physician characteristics influence patient care, this study aimed to explore thyroid specialist profiles and associations with geo-economic factors. METHODS: Thyroid specialists from 28 countries were invited to respond to a questionnaire, Treatment of Hypothyroidism in Europe by Specialists: an International Survey (THESIS). Geographic regions were defined according to the United Nations Statistics Division. The national economic status was estimated using World Bank data on the gross national income per capita (GNI per capita). RESULTS: 5,695 valid responses were received (response rate 33·0%). The mean age was 49 years, and 65·0% were female. The proportion of female respondents was lowest in Northern (45·6%) and highest in Eastern Europe (77·2%) (p <0·001). Respondent work volume, university affiliation and private practice differed significantly between countries (p<0·001). Age and GNI per capita were correlated inversely with the proportion of female respondents (p<0·01). GNI per capita was inversely related to the proportion of respondents working exclusively in private practice (p<0·011) and the proportion of respondents who treated >100 patients annually (p<0·01). DISCUSSION: THESIS has demonstrated differences in characteristics of thyroid specialists at national and regional levels, strongly associated with GNI per capita. Hypothyroid patients in middle-income countries are more likely to encounter female thyroid specialists working in private practice, with a high workload, compared to high-income countries. Whether these differences influence the quality of care and patient satisfaction is unknown, but merits further study.

3rd Department of Medicine 1st Faculty of Medicine Charles University General University Hospital Prague Czechia

5th Department of Internal Medicine Medical Faculty of Commenius University and University Hospital Bratislava Slovakia

5th Medical Department Division of Endocrinology and Diabetes Medical Faculty Mannheim Heidelberg University Mannheim Germany

Associazione Medici Endocrinologi Scientific Committee Milan Italy

Cabinet Médical 2 Rue Bellefontaine Lausanne Switzerland

Clinic of Endocrinology Diabetes and Diseases of Metabolism Thyroid Department Belgrade Serbia

Department of Endocrinology and Diabetes Centre Hellenic Red Cross Hospital Athens Greece

Department of Endocrinology and Metabolism Amsterdam UMC University of Amsterdam Amsterdam Netherlands

Department of Endocrinology and Metabolism Koru Ankara Hospital Ankara Türkiye

Department of Endocrinology and Metabolism Regina Apostolorum Hospital Albano Laziale Roma Italy

Department of Endocrinology and Nutrition Cliniques Universitaires St Luc Université Catholique De Louvain Brussels Belgium

Department of Endocrinology Belarusian State Medical University Minsk Belarus

Department of Endocrinology Carol Davila University of Medicine and Pharmacy Bucharest Romania

Department of Endocrinology Diabetes and Metabolic Diseases Mladen Sekso University Hospital Center Sisters of Mercy Zagreb Croatia

Department of Endocrinology Diabetes and Metabolism Medical Faculty University of Coimbra Coimbra Portugal

Department of Endocrinology Hospital Universitario Puerta De Hierro Majadahonda Madrid Spain

Department of Endocrinology Metabolism and Internal Medicine Poznan University of Medical Sciences Poznan Poland

Department of Endocrinology No 1 N 5 Sklifosovsky Institute of Clinical Medicine 1 M Sechenov 1st Moscow State Medical University Moscow Russia

Department of Endocrinology Odense University Hospital Odense Denmark

Department of Endocrinology Skåne University Hospital Malmö Sweden

Department of Internal Medicine and Endocrinology Medical University of Warsaw Warsaw Poland

Department of Internal Medicine Division of Endocrinology Faculty of Medicine Gaziantep University Gaziantep Türkiye

Department of Internal Medicine Endocrine Unit UZ Brussel Vrije Universiteit Brussel Brussel Belgium

Department of Internal Medicine Tampere University Hospital Tampere Finland

Department of Medicine 1 Klinikum Vest GmbH Knappschaftskrankenhaus Recklinghausen Recklinghausen Germany

Department of Medicine 3 Division of Endocrinology Medical University of Vienna Vienna Austria

Department of Medicine Universidad Autónoma De Madrid Madrid Spain

Department of Reproductive Endocrinogy Institute of Endocrinology and Metabolism named after 5 P Komissarenko National Academy of Medical Science of Ukraine Kyiv Ukraine

Department of Surgery Tampere University Hospital Tampere Finland

Departmento De Endocrinologia e Nutrición Clínica Universidad De Navarra Pamplona Spain

Diabetes and Endocrinology Section Beacon Hospital Dublin Ireland

Division of Endocrinology Department of Medicine Faculty of Medicine University of Debrecen Debrecen Hungary

Division of Endocrinology Diabetology and Metabolism University of Lausanne Lausanne Switzerland

East Surrey Hospital Surrey and Sussex Healthcare NHS Trust Redhill Surrey United Kingdom

Endocrine Unit and Diabetes Centre Department of Clinical Therapeutics Alexandra Hospital National and Kapodistrian University of Athens Faculty of Medicine Athens Greece

Endocrinology Diabetes and Metabolism Service Porto Hospital and University Centre Porto Portugal

Endocrinology Institute Rabin Medical Center Tel Aviv University Sackler Faculty of Medicine Tel Aviv Israel

GRC n 16 GRC Thyroid Tumors Thyroid Disease and Endocrine Tumor Department AP HP Hôpital Pitié Salpêtrière Sorbonne University Paris France

Hopital Pitie Salpetriere Thyroid and Endocrine Tumors Unit Institut of Endocrinology Sorbonne University Paris France

Institute of Endocrinology and Metabolism named after 5 P Komissarenko National Academy of Medical Science of Ukraine Kyiv Ukraine

Institute of Translational and Clinical Research Newcastle University Newcastle Upon Tyne United Kingdom

Instituto De Investigación Sanitaria Puerta De Hierro Segovia De Arana Majadahonda Madrid Spain

Minsk Endocrinology Medical Center Minsk Belarus

Ospedale Vito Fazzi Department of Endocrinology Lecce Italy

P J Šafárik University Košice 1st Department of Internal Medicine of the Medical Faculty Košice Slovakia

Rabin Medical Center Tel Aviv University Tel Aviv Israel

Robert Graves Institute Tallaght University Hospital Dublin Ireland

Rotterdam Thyroid Center Department of Internal Medicine Erasmus MC Rotterdam Netherlands

School of Medicine University College Dublin Dublin Ireland

Sofia University Saint Kliment Ohridski Medical Faculty Clinic of Endocrinology and Metabolism University Hospital Sofiamed Sofia Bulgaria

Thyroid Endocrinology Osteoporosis Institute Dobnig Graz Austria

University Hospital Alexandrovska Clinic of Endocrinology and Metabolism Medical University Sofia Internal Medicine Sofia Bulgaria

University Hospital Essen Department of Endocrinology Diabetes and Metabolism University Duisburg Essen Essen Germany

University of Belgrade Faculty of Medicine Internal Medicine Belgrade Serbia

University of Surrey Faculty of Health and Medical Sciences Section of Clinical Medicine Prague United Kingdom

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