Real-World VTE Prophylaxis Practices in US Orthopedic Surgery Patients: An Analysis of An Integrated Healthcare Database.
Authors: Merli Geno J , Malangone Elisabetta , Lin Jay , Stern Lee 
Published: October 2019

Abstract
Abstract 1075
Poster Board I-97

Introduction:
Major orthopedic surgery patients are at high risk of venous thromboembolism (VTE), with a VTE incidence of 40-60% in patients that do not receive thromboprophylaxis. However, the incidence of VTE can be significantly reduced with the use of evidence-based thromboprophylaxis such as low-molecular-weight heparins (LMWH) and warfarin. Although prophylaxis is often provided in-hospital, there is frequently a break in the continuum of VTE prophylaxis on discharge, despite the applicability of LMWH or warfarin for outpatient prophylaxis. The purpose of this study is to describe real-world inpatient and outpatient pharmacological prophylaxis practices of patients undergoing major orthopedic surgery.

Methods:
Patients greater than 18 years of age in a large, vertically integrated Midwestern healthcare system (January 1995 to June 2008) and with a Current Procedural Terminology (CPT) code for predetermined knee and hip orthopedic surgeries were eligible for this study. Patients with atrial fibrillation or less than 18 months of continuous health plan enrollment (including a minimum of 1-year post-discharge) were excluded from the analyses. Prophylaxis therapy was assessed during the first year of follow-up and stratified by inpatient versus outpatient therapy. Characteristics of prophylaxis use, such as anticoagulation duration, prophylaxis type stratified by surgery, and mean INR were also examined.

Results:
A total of 2382 patients were included in the analysis, with 1393 (58.5%) undergoing total knee arthroplasty (TKA) and 989 (41.5%) undergoing total hip arthroplasty (THA). The average length of hospital stay was 4.7 days in TKA patients and 5.1 days in THA patients. When considering prophylaxis use, 72.7% of TKA patients received inpatient pharmacological prophylaxis alone, 12.5% received inpatient and outpatient pharmacological prophylaxis, 3.5% received only outpatient pharmacological prophylaxis and 11.3% received no pharmacological prophylaxis (Table). Similarly in THA patients, 73.2% received inpatient pharmacological prophylaxis alone, 12.4% received inpatient and outpatient pharmacological prophylaxis, 3.2% received only outpatient pharmacological prophylaxis and 10.9% received no pharmacological prophylaxis. In both TKA and THA patients, the most frequent inpatient prophylaxis therapy was low-molecular-weight heparin (90.6% and 85.6%, respectively). In those patients that received warfarin, the majority (67.9%) had a mean INR between 1 and 2 during the first 2 months.

Conclusions:
This analysis highlights the short duration of prophylaxis provided to US orthopedic surgery patients. Despite these patients having mean hospital stays of approximately 5 days and guidelines recommending a minimum of 10 days of prophylaxis for major orthopedic surgery patients, only approximately 15% of patients received outpatient prophylaxis.

Disclosures:
Merli: sanofi-aventis: Consultancy, Research Funding, Speakers Bureau, The authors received editorial/writing support in the preparation of this abstract funded by sanofi-aventis U.S., Inc.; AstraZeneca: Consultancy, Research Funding, Speakers Bureau; Boehringer Ingelheim: Research Funding; Bayer: Consultancy; Bacchus Scientific: Consultancy. Malangone:sanofi-aventis: Research Funding. Lin:sanofi-aventis: Employment. Stern:sanofi-aventis: Research Funding.