Shifting Paradigm In Physician Practice Patterns In The Application Of Thromboprophylaxis Guidelines: An Updated Analysis Of Venous Thromboembolism Prevention At a University-Affiliated Tertiary Care Center
Authors: Ma Kim A. , Eva Cohen , Kahn Susan R. 
Published: October 2019

Abstract

Background
Venous thromboembolism (VTE) is an important cause of morbidity and mortality in hospitalized patients. Prophylactic antithrombotic therapy has been shown to be the most effective method to reduce the health and economic burden of an often silent disease. The American College of Chest Physicians (ACCP) has been instrumental in developing guidelines for the use of prophylactic antithrombotic therapy. However, several studies have consistently demonstrated underuse of these guidelines. One such study, conducted in 2001 at our university- affiliated hospital (Jewish General Hospital, Montreal, Canada), showed that 17.4% of all VTE cases in hospitalized patients were potentially avoidable (Arnold DM, Kahn SR, et al. Chest2001) and that this represented 2/3 of all VTE cases for which thromboprophylaxis had been indicated. Consequently, in 2005, we implemented an institution-wide thromboprophylaxis policy with the aim of improving VTE prevention. Five years after this change, we reassessed physician practice patterns at our institution with regards to application of thromboprophylaxis guidelines, and determined the avoidability of each case of VTE.

Objective
To identify and characterize cases of potentially avoidable VTE: cases for which thromboprophylaxis was indicated according to ACCP consensus guidelines for VTE prevention, yet was administered inadequately.

Methods
We conducted a retrospective cohort study, which included all patients with objectively diagnosed VTE who were admitted in 2010 to the Jewish General Hospital, a university-affiliated tertiary care institution. A standardized case-report form was used to obtain data from patient charts on patient characteristics, risk factors for VTE, risk factors for bleeding, presence of indications for thromboprophylaxis as per ACCP guidelines (e.g. surgery in last 3 months, hospitalization for pneumonia), and thromboprophylaxis regimen received. Each case was classified as avoidable (a case in which thromboprophylaxis was indicated but inadequately administered), non-avoidable (a case in which thromboprophylaxis was indicated and was correctly administered), spontaneous (a case in which a VTE occurred with no evident indications for thromboprophylaxis), and ineligible (a case in which there was either contraindication to thromboprophylaxis, or which occurred at another institution). The proportions with avoidable, non-avoidable and spontaneous VTE were compared to the results we obtained in our 2001 study.

Results
Of the 230 cases of VTE diagnosed in 219 patients, 55 cases were classified as avoidable (23.9%), 87 were non-avoidable (37.8%), and 74 were spontaneous (32.2%). Therefore, of the 142 (i.e. 55+87) cases for which thromboprophylaxis was indicated, 38.7% were potentially avoidable. Of the avoidable VTE cases, the majority (51.0%) were due to omission of thromboprophylaxis, with another 40.0% due to delay in initiation of thromboprophylaxis. The majority (75%) of avoidable cases occurred during general medical admissions, with a minority occurring in the context of orthopedic surgery. Common additional VTE risk factors in avoidable cases were cancer, obesity and prolonged immobility.

Conclusions
1 in 4 cases of all VTE, and 1 in 2.5 cases of VTE for which thromboprophylaxis was indicated could potentially have been avoided had thromboprophylaxis been administered according to ACCP guidelines. The ratio of avoidable to non-avoidable cases (38.7%; 1 in 2.5) has significantly improved since 2001(67.7%; 2 in 3). Physician education and the adoption of an institution-wide protocolized approach to thromboprophylaxis may be largely responsible for this favorable shift. However, there has also been a significant decrease in the number of VTE cases deemed “spontaneous” from 2001 to 2010 (70.8% to 32.2%). During this time period, there were no major guideline changes in indications for VTE prophylaxis that might have led to fewer VTE being labeled spontaneous and more VTE being labeled provoked. The decrease in spontaneous cases of VTE might be ascribable to a change in patient population (e.g. increased numbers of hospitalizations for malignancy-related complications), as well as a shift towards having a lower threshold to identify patients as having risk factors for VTE (e.g. patients with pneumonia, non-fracture injuries).

Disclosures:
No relevant conflicts of interest to declare.