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DOACs use in extreme body-weighted patients: results from the prospective START-register

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Direct oral anticoagulants (DOACs) are widely used for the treatment of venous thromboembolism (VTE) and for stroke prevention in atrial fibrillation (AF). However, evidence in obese and underweight patients is limited. We assessed the safety and effectiveness of DOACs and vitamin K antagonists (VKAs) in patients  ≥ 120 kg or ≤ 50 kg enrolled in an observational prospective cohort study, the START-Register.


Adult patients started on anticoagulant therapy were followed up for a median of 1.5 years (IQR 0.6–2.8). Primary efficacy outcome was the occurrence of VTE recurrence, stroke and systemic embolism. Primary safety outcome was major bleeding (MB).


10,080 AF and VTE patients were enrolled between March 2011 and June 2021, 295 patients weighted  ≤ 50 kg and 82 patients ≥ 120 kg. Obese patients were significantly younger than underweight patients. Rates of thrombotic events were low and similar between DOACs and VKAs in underweight patients (1 event on DOACs therapy [0.9% 95% CI 0.11–5.39] and 2 on VKAs [1.1% 95% CI 0.01–47.68]) and in overweight patients (0 events on DOACs, 1 on VKAs [1.6%, 95% CI 0.11–5.79]. Two MB events occurred on DOACs (1.9%, 95% CI 0.38–6.00) and 3 on VKAs (1.6%, 95% CI 0.04–22.06) in the underweight group; 1 MB on DOACs (5.3% 95% CI 0.33–16.68) and 2 on VKAs (3.3%, 95% CI 0.02–130.77) in the overweight group.


DOACs seem to be effective and safe also for the treatment of patients with extreme body weights, both underweight and overweight. Further prospective studies are needed to support these findings.

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The following Investigators and Centers participated to the START2-Register: Benilde Cosmi, UO Angiologia e Malattie della Coagulazione, Azienda Ospedaliero Universitaria. S. Orsola—Malpighi, Bologna. Walter Ageno, Giovanna Colombo, Dipartimento di Emergenza e Accettazione, Centro Trombosi. ed Emostasi, Ospedale di Circolo, Università dell’Insubria, Varese. Doris Barcellona, Struttura Dipartimentale di Emostasi e Trombosi, AOU di Cagliari, Dipartimento di Scienze Mediche e Sanità Pubblica, Università di Cagliari, Cagliari. Barbara Bresciani, Cardiologia, Ospedale di Bentivoglio ASL Bologna, Bologna. Eugenio Bucherini, Struttura Semplice Dipartimentale, Medicina Vascolare-Angiologia, Ospedale Civile Faenza, Faenza (RA). Paola Casasco, Centro diagnosi trombosi e sorveglianza terapia anticoagulanti, Immunoematologia Trasfusionale, Ospedale SS. Antonio e Margherita, Tortona (AL). Paolo Chiarugi, Ambulatorio Antitrombosi per la sorveglianza dei pazienti in terapia anticoagulante. orale, U.O. Analisi Chimico-Cliniche, Azienda Ospedaliero Universitaria Pisana, Pisa. Antonio Chistolini, Alessandra Serrao, Sezione Ematologia, Dipartimento di Biotecnologie. Cellulari ed Ematologia, Azienda Ospedaliero Universitaria Policlinico Umberto I, Roma. Valeria De Micheli, Centro Emostasi e Trombosi, Ospedale di Lecco, Lecco. Marcello Di Nisio, Medicina Vascolare e Malattie Trombemboliche, Ospedale Annunziata, Pescara. Anna Falanga, Teresa Lerede, Luca Barcella, USC SIMT, Centro Emostasi e Trombosi, Ospedale Papa Giovanni XXIII, Bergamo. Vittorio Fregoni UOC Medicina Generale ASST Val Lario, Sondalo (Sondrio). Elvira Grandone, Donatella Colaizzo, Centro Trombosi Casa del Sollievo e della Sofferenza, S. Giovanni Rotondo (Foggia). Antonio Insana, Laboratorio Analisi, Ospedale Mauriziano, Torino. Giuseppe Malcangi, Centro Emofilia e Trombosi, Policlinico di Bari, Bari. Catello Mangione, Trasfusionale, Ospedale di Galatina, Galatina (LE). Giuliana Martini, Centro Emostasi, Spedali Civili Di Brescia, Brescia. Lucilla Masciocco, Pasquale Saracino, Centro Controllo Coagulazione, Dipartimento di Medicina-Geriatria-Lungodegenza, Ospedali Riuniti Riuniti-Foggia, Presidio Ospedaliero Lastaria, Lucera (Foggia). Daniela Mastroiacovo, Dipartimento di Angiologia, Ospedale SS. Filippo e Nicola, Avezzano (L’Aquila). Marco Marzolo, UOC Medicina Interna, Ospedale di Rovigo, Rovigo. Vincenzo Oriana, Centro Emofilia, Servizio Emostasi e Trombosi, Azienda Bianchi Melacrino. Morelli, Reggio Calabria. Carmelo Paparo, Patologia Clinica, Ospedale Maggiore, Chieri (Torino). Simona Pedrini, Federica Bertola, Servizio di Laboratorio, Istituto Ospedaliero Fondazione. Poliambulanza Brescia, Brescia. Vittorio Pengo, Gentian Denas, Elisa Bison, Dipartimento di Scienze Cardio-Toraco-Vascolari, Centro Trombosi, AOU Padova, Padova. Antonietta Piana, Francesco Cibecchini, Centro Prevenzione e Cura Malattie Tromboemboliche. Azienda Ospedaliera Universitaria San Martino IST, Genova. Pasquale Pignatelli, Daniele Pastori, Centro Trombosi, Clinica Medica Policlinico Umberto I°, Roma. Gian Marco Podda, Simone Birocchi, Medicina Interna ASST Santi Paolo e Carlo, Milano. Daniela Poli, Rossella Marcucci, Niccolò Maggini, SOD Malattie Aterotrombotiche, Azienda. Ospedaliero Universitaria-Careggi, Firenze. Angelo Porfidia, UOC Medicina Generale, Policlinico Universitario Gemelli, Roma. Serena Rupoli, Clinica Ematologica, Ospedali Riuniti Ancona, Ancona. Domizio Serra, Centro Trombosi, Ospedale Evangelico Internazionale, Genova. Sophie Testa, Oriana Paoletti, Centro Emostasi e Trombosi, Laboratorio Analisi chimico-cliniche. e microbiologiche, Azienda Socio Sanitaria Territoriale di Cremona, Cremona. Andrea Toma, Pietro Barbera, UOC di Patologia Clinica, Ambulatorio Terapia Anticoagulante. Orale, O.C. “L.Cazzavillan”, Arzignano (Vicenza). Alberto Tosetto, Divisione di Ematologia, Ospedale San Bortolo, Vicenza. Claudio Vasselli, Laboratorio Patologia Clinica, Policlinico Casilino, Roma. Adriana Visonà, Beniamino Zalunardo UOC Angiologia, Ospedale San Giacomo Apostolo, Castelfranco Veneto (Treviso). Maddalena Loredana Zighetti, SIMT- AO San Paolo, Milano.

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Guarascio, M., Bertù, L., Donadini, M.P. et al. DOACs use in extreme body-weighted patients: results from the prospective START-register. Intern Emerg Med 18, 1681–1687 (2023).

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