Standard of Care Evaluation of Venous Thromboembolism Prophylaxis in Selected Solid Tumour Patients at a Tertiary Cancer Care Teaching Hospital.
Authors: Donck Colleen , Huh Jin , Seki Jack , Chen Eric , Yeo Erik 
Published: April 2020

Abstract
Contemporary evidence suggests thromboprophylaxis in medical oncology patients may be effective, however, according to global surveys, is greatly underutilized despite the substantial risk of venous thromboembolism (VTE). To date, routine thromboprophylaxis of medical oncology inpatients has not been evaluated at a cancer care institution. Not equally common in all types of cancer, VTE is thought to present a higher risk in selected solid tumours of the CNS, lung, gastrointestinal and genitourinary tracts. Recommendations from the Sixth ACCP Consensus Conference on Antithrombotic Therapy include implementing institution-specific VTE prophylaxis guidelines for high-risk patients. The objectives of this study are to develop and implement targeted VTE prophylaxis guidelines for high-risk solid tumour inpatients during admission to a medical oncology ward and to evaluate the impact on prescribing practice. The study is a prospective, observational, before and after chart review with retrospective validation. VTE prophylaxis guidelines were developed through literature review and expert consensus. The results presented are the baseline pre-phase data over 14 weeks. Of nearly 240 charts assessed for eligibility criteria, 92 (39%) were stratified as high-risk according to the developed guidelines based on tumour site. Seventy-two of those patients identified as high-risk were followed prospectively to determine the baseline rates of thromboprophylaxis and venographically confirmed symptomatic VTE. Retrospective validation of results was performed in all 237 patients. Current results of the pre-phase revealed appropriate VTE prophylaxis with a low-molecular weight heparin based on the proposed guidelines in three eligible patients (5.3%). A total of 13 eligible patients (19%) received any form of pharmacological or non-pharmacological prophylaxis. The rate of symptomatic VTE was 11% (n = 10) among high-risk patients of which five patients developed pulmonary embolus (PE), four patients presented with deep vein thrombosis (DVT) and one patient developed portal vein thrombosis. Among non high-risk patients, the rate of symptomatic VTE was significantly lower at 3% (n = 5), among which three patients presented with PE and two patients developed DVT. In both groups, pulmonary embolus was the most common manifestation of VTE. No clinically significant bleeding occurred during prophylaxis. The rate of symptomatic VTE among the highly selected at-risk medical oncology population at this institution was substantially different than the non high-risk population and is in accordance with the literature. This study presents new data on the rates of symptomatic VTE and thromboprophylaxis for medical oncology patients in a hospital setting. The rate of VTE prophylaxis of 5.3% seen in the pre-phase appears unacceptably low given that appropriate pharmacological intervention may potentially reduce the VTE rate by as much as 50% as suggested by relevant literature. As such, implementation of VTE prophylaxis guidelines at this cancer care center is ongoing.