The equipoise of perioperative anticoagulation management: a Canadian cross-sectional survey

Warfarin anticoagulation is indicated for the treatment of venous thromboembolism (VTE). Anticoagulation management around the time of surgery is uncertain and while perioperative anticoagulation guidelines exist, there is little evidence to support an optimal management strategy in patients with VTE [1]. Furthermore, rivaroxaban, an oral direct factor Xa inhibitor, is increasingly being prescribed for VTE treatment [2]. The only guide for perioperative rivaroxaban management are expert opinion reviews largely based on drug pharmacokinetic profiles [3, 4]. Given the lack of evidence for perioperative strategies, we sought out to assess general practices among Canadian specialists who manage perioperative anticoagulation. In January 2013, we completed a cross-sectional Canadian survey among hematologists and general internal medicine (GIM) specialists. The survey was distributed to 480 individuals on-line using SurveyMonkey , with an invitation to the survey hyperlink distributed via e-mail. Specifically, we contacted the members of the Thrombosis Interest Group of Canada (TIGC), a group of 72 healthcare professionals with an interest in venous and arterial thromboembolic disease. Without the availability of a centralized database for GIM physicians, we contacted GIM division directors at Canadian academic centers, who then distributed the survey to general internists regularly involved in perioperative care. A second reminder e-mail to complete the survey was sent. The survey assessed perioperative warfarin management using four hypothetical scenarios involving a 70-year old man with a recurrent idiopathic DVT/PE diagnosed 5 months ago, undergoing a (1) outpatient prostate biopsy, (2) laparoscopic cholecystectomy (overnight stay), (3) inpatient colostomy reversal for colon cancer, and (4) inpatient right knee replacement. The management options included a temporary cessation of warfarin 5 days before the procedure with the option to (a) resume warfarin postoperatively with no low-molecular-weight heparin (LMWH) use, (b) prophylactic-dose LMWH given before and after the procedure, (c) prophylactic-dose LMWH only after the procedure, (d) therapeutic-dose LMWH before and after the procedure, or (e) therapeutic-dose LMWH only after the procedure. We included a sixth open response option so participants could describe other management strategies. There were two questions that assessed the perioperative management of rivaroxaban. The survey was pre-tested (M.K. and A.L.L.). The data was collected online using SurveyMonkey and entered into a database for analysis. 95 % confidence intervals for proportions were calculated using the Wilson’s score method (OpenEpi Version 3) [5]. Proportions were calculated using the total number of respondents for each question. Of the 480 surveys that were distributed, 76 individuals responded (16 %). There were 52 general internists (68.4 %), 19 hematologists (26.3 %), and 5 respondents who classified themselves as ‘other’ (identified as: 1 thrombosis physician, 2 cardiologists with a thrombosis interest and 2 anticoagulation clinic pharmacists). The responses to four clinical scenarios involving perioperative warfarin management are summarized in Table 1. L. Skeith A. Lazo-Langner M. J. Kovacs (&) Division of Hematology, Department of Medicine, London Health Sciences Centre, 800 Commissioners Rd E, London, ON N6A 5W9, Canada e-mail: michael.kovacs@lhsc.on.ca