Retrospective Analysis of Adherence to Thromboprophylaxis after Orthopedic Surgery in a Community Hospital

Abstract

Venous thromboembolism is a well-known complication of total knee replacement, total hip replacement, and hip fracture repair. Venous thromboembolism, which includes deep vein thrombosis and pulmonary embolism, can cause significant morbidity and mortality. In addition, treatment of this condition can result in substantial costs to the health care system. Patients who have undergone orthopedic surgery are considered at high risk for these complications, with the rate of venous thromboembolism approaching 40% to 60% among patients who have not received postoperative thromboprophylaxis. Rates of venous thromboembolism have decreased significantly with the use of guideline-recommended thromboprophylaxis. Because many cases of venous thromboembolism occur after discharge from hospital, postdischarge prophylaxis is an important component of treatment. Thromboprophylaxis for patients who have undergone orthopedic surgery has been the standard of care for more than 15 years. The 2008 guidelines of the American College of Chest Physicians (ACCP) recommended the use of a low molecular-weight heparin (LMWH), fondaparinux, or a vitamin K antagonist (e.g., warfarin) for at least 10 days after total knee replacement and for an extended period of up to 28–35 days after total hip replacement or hip fracture repair. Although patients who have undergone orthopedic surgery are generally considered to be at high risk for venous thromboembolism, individual patient risk factors also influence the occurrence of this problem. Additional risk factors include immobility, cancer, previous venous thromboembolism, older age, and obesity. Risk stratification has historically been used to make decisions about thromboprophylaxis for individual patients; however, such stratification is often not done in practice because it is quite cumbersome. With the availability of LMWH, the use of warfarin has been decreasing steadily in this patient population, which avoids the need to monitor the international normalized ratio (INR) and titrate warfarin to a target INR of 2–3. However, several barriers still exist to providing appropriate thromboprophylaxis with LMWH in this patient population. Because thromboprophylaxis of at least 10 days (for total knee replacement) and of extended duration (for total hip replacement or hip fracture surgery) has been shown to reduce the risk of venous thromboembolism, it is remarkable that more patients are not receiving postdischarge therapy, especially given that a recent meta-analysis showed no significant increase in episodes of major bleeding when these agents were used for this purpose. The results of studies evaluating in-hospital adherence to available guidelines have been disappointing, with most adherence rates being suboptimal. Adherence with postdischarge thromboprophylaxis is also important, given reports that the majority of cases of thromboembolism after total hip and knee replacement are diagnosed after discharge. The primary objective of this retrospective analysis was to examine the rate of adherence to the 2008 ACCP guidelines for the appropriate duration of postoperative therapy with LMWH or warfarin among orthopedic patients in an urban community hospital. Previous studies of adherence have rarely reported postdischarge compliance, but for this study, in-hospital data were combined with community data to generate the total duration of therapy.