OBJECTIVE: The aim of this study was to evaluate the prevalence of venous thromboembolism (VTE) in patients included in the European Registry on Cushing's syndrome (ERCUSYN), compare their clinical characteristics with those who did not develop VTE and identify risk factors for VTE. DESIGN: A retrospective observational cohort study. METHODS: Data extraction from the registry was taken on February, 7, 2022. At the time there were 2174 patients diagnosed with Cushing's syndrome (CS) and 95 VTEs were reported in the database. RESULTS: Of 95 VTE events 70 (74%) were in pituitary-dependent CS patients, 12 (12.5%) in adrenal-dependant CS, 10 (10.5%) in ectopic CS, and 3 (3%) in CS due to other causes. Sex, 24-hour urinary free cortisol (UFC) value at diagnosis, as well as the number of operations remained statistically significant predictors of VTE. Of patients who were treated with at least one surgery, 12 (13%) VTE occurred before and 80 (87%) after the surgery. Nearly half of these VTEs occurred within six months since the operation (36; 45%). Over half of the centers that reported VTE did not routinely anticoagulate CS patients. Anticoagulation schemes varied widely. CONCLUSION: Patients with CS have an elevated risk of developing VTE for an extended period of time. From ERCUSYN cohort patients have higher risk for VTE if they need multiple surgeries to treat CS, are males and have high UFC values at the diagnosis of CS. Since there is no agreement on thromboprohpylaxis, a protocol for VTE prevention that is widely adopted appears to be necessary for patients with CS.

3rd Department of Internal Medicine 1st Faculty of Medicine Charles University General University Hospital 12808 Prague Czech Republic

Aix Marseille Univ APHM INSERM MMG Department of Endocrinology Hospital La Conception MarMaRa Institute 13305 Marseille France

Centro de Investigación Biomédica en Red de Enfermedades Raras Barcelona Spain

Clinical Endocrinology Charite Universitätsmedizin Campus Mitte 10117 Berlin Germany

Department of Clinical Epidemiology and Public Health Hospital de la Santa Creu i Sant Pau 08025 Barcelona Spain

Department of Endocrinology and Metabolism Amsterdam University Medical Center and University of Amsterdam 1081 Amsterdam Netherlands

Department of Internal Medicine and Oncology Semmelweis University 1083 Budapest Hungary

Department of Internal Medicine Section of Endocrinology ENETS Center of Excellence Erasmus MC and Erasmus Cancer Institute 3015 Rotterdam The Netherlands

Division of Endocrinology and Diabetes Department of Internal Medicine 1 University Hospital University of Würzburg 97080 Würzburg Germany

Endocrinology and Nutrition Department Germans Trias i Pujol Hospital and Research Institute Badalona 08916 Spain

Health Care Consulting GmbH Lohmann and Birkner Health Care Consulting GmbH 13407 Berlin Germany

IIB Sant Pau and Department of Endocrinology Hospital Sant Pau Dept Medicine UAB and Centro de Investigación Biomédica en Red de Enfermedades Raras ISCIII 08025 Barcelona Spain

Institute of Biomedicine and Translational Medicine University of Tartu Ülikooli 18 50090 Tartu Estonia

Medizinische Klinik und Poliklinik 4 Campus Innenstadt Klinikum der Universität München Ludwig Maximilians Universität München 80336 Munich Germany

Oxford Centre for Diabetes Endocrinology and Metabolism Oxford University Hospitals OX37LE Oxford United Kingdom

University Grenoble Alpes UMR 1292 INSERM CEA UGA Endocrinologie CHU Grenoble Alpes F 38000 Grenoble France

Zentrum für Endokrinologie Diabetologie Rheumatologie Dr Demtröder and Kollegen 44137 Dortmund Germany

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