Abstract
Context: Guidelines on the use of prophylaxis in venous thromboembolism (VTE) are poorly implemented in clinical practice.
Objective: To evaluate the extent to which the American College of Chest Physicians (ACCP) 2001 guidelines on VTE prophylaxis are adhered to in clinical practice by determining whether patients admitted to a medical center with an objective diagnosis of VTE had received adequate prophylaxis.
Methods: The medical records of medical and surgery patients with an objective diagnosis of VTE were reviewed. Patients were classified as having either preventable or nonpreventable VTE according to indication for prophylaxis, VTE risk, and adequacy of prophylaxis if administered. Adequacy was determined by adherence to the ACCP 2001 guidelines.
Results: Of 44 patients, 17 (38.6%) had not received adequate prophylaxis and were classified as having potentially preventable VTE. Venous thromboembolism developed in the remaining 27 (61.4%) patients despite adequate prophylaxis. In general, adequate prophylaxis rates were lower among surgery patients compared with medical patients. Four (80%) of the very-high-risk surgery patients received inadequate prophylaxis. The most common VTE risk factor in both categories was immobility.
Conclusions: Adherence to the ACCP guidelines is suboptimal, with a substantial proportion of patients with VTE receiving inadequate prophylaxis. The additional finding that the incidence of VTE is high despite adequate prophylaxis indicates that the guidelines may need to be reevaluated.
Venous thromboembolism (VTE), which encompasses both deep vein thrombosis (DVT) and pulmonary embolism (PE), is a major cause of morbidity and mortality in hospitalized patients.
1 It has been estimated that more than 450,000 patients are hospitalized annually in the United States for VTE.
1 Furthermore, because only one in every three cases of VTE is detected, the actual incidence in the United States may be about 1,350,000 annually.
1 An analysis of data from the International Cooperative Pulmonary Embolism Registry revealed a crude 3-month mortality rate from VTE as high as 17.5%.
2 Venous thromboembolism has few specific symptoms and is clinically “silent” in most patients, making diagnosis difficult and unreliable.
1 For this reason, prophylactic treatment methods are recommended for patients at risk for VTE.
3
In general, the translation of clinical trial data to routine clinical practice is a gradual process involving the creation of evidence-based guidelines that are updated regularly. The Sixth American College of Chest Physicians (ACCP) Consensus Conference on Antithrombotic Therapy (2001) published evidence-based guidelines concerning the use of VTE prophylaxis, which were subsequently updated in 2004.
3,4 The ACCP guidelines recommend mechanical and pharmacologic methods of prophylaxis based on specific VTE risk factors, such as prolonged immobility, cancer, or major surgery.
3 Mechanical prophylaxes include thromboembolic deterrent stockings, intermittent pneumatic compression, and inferior vena cava filters. Anticoagulation therapy with low–molecular weight heparin is a common pharmacologic prophylaxis.
Studies have shown that the implementation of these and other guidelines for VTE prophylaxis is inadequate or inconsistent.
5–9 For example, Arnold et al
7 analyzed 253 VTE cases diagnosed at a Montreal general hospital and showed that 68% of patients with an indication for VTE prophylaxis had not received prophylaxis in accordance with the ACCP 1995 guidelines. Of these patients, 48% had not received prophylaxis at all.
7
Physicians' nonadherence to the guidelines may be due to factors such as lack of awareness or knowledge of the guidelines, a perception that VTE prophylaxis is ineffective, or the view that VTE is not a significant problem.
10–12 Swan and Spigelman
11 found that surgeons may underestimate the post-surgical risk of VTE because of a lack of awareness regarding patient readmissions with VTE. Consequently, VTE is believed to be a rare occurrence.
11
Hospital and clinical practice audits as well as educational programs have increased the adoption of new guidelines in some instances.
13–15 New protocols and audit procedures in the Scottish Intercollegiate Guidelines Network on the prevention of VTE was shown to increase the number of at-risk patients who were prescribed the correct prophylaxis, from 55% to 96%.
14 Similarly, a pharmacy-based educational program designed to promote VTE prophylaxis guidelines significantly increased the level of appropriate prophylaxis from 59% to 70% of patients.
15
The objective of this study was to evaluate the extent to which the ACCP 2001 guidelines on VTE prophylaxis are adhered to in clinical practice by determining whether patients admitted to a medical center with an objective diagnosis of VTE had received adequate VTE prophylaxis. Adequate prophylaxis was determined by comparing the prophylaxis regimens used with those recommended by the ACCP 2001 guidelines for specific indications and risk groups.
This retrospective study was designed to assess whether patients with a diagnosis of VTE had received adequate prophylaxis according to the ACCP 2001 guidelines. Medical records of patients with a confirmed diagnosis of VTE admitted to a medical center from June 2002 to May 2003 were reviewed to determine indications for and adequacy of prophylaxis. The study period was chosen to allow sufficient time for the ACCP 2001 guidelines on VTE prophylaxis to have been widely implemented in clinical practice.
Data were collected for each patient on risk factors for VTE, indications for VTE prophylaxis according to the ACCP guidelines, and the VTE prophylaxis used. Based on these data, each patient was classified as having either preventable or nonpreventable VTE. Patients were objectively diagnosed using Doppler ultrasonography, a ventilation-perfusion scan, or a computerized tomographic angiogram.
The patients' medical records were examined for any risk factors for VTE, including a history of VTE, cancer, central venous catheter lines, cerebrovascular accident, congestive heart failure, hypercoagulation, immobility, myocardial infarction, obesity, oral contraceptive use, pneumonia, and recent lower extremity fracture.
Patients were first grouped according to the ACCP guidelines into those with surgical (surgery patients) and those with medical (medical patients) indications. Surgical indications outlined in the guidelines include general surgery (ie, cardiac, gynecologic, laparoscopic, neurologic, urologic, and vascular); multiple trauma procedures; and orthopedic surgery, including hip and knee arthroplasty, hip repair surgery, and elective spine surgery. Medical indications include cerebrovascular accident and spinal cord injuries with paralysis, chest infections and pneumonia, congestive heart failure, and hospital admission secondary to myocardial infarction or stroke. Surgery patients were further stratified according to VTE risk into one of the following risk groups as detailed in the ACCP 2001 guidelines:
The ACCP 2001 guidelines outline recommendations for VTE prophylaxis, including type of prophylaxis and dosing regimen, according to the indication and the patient's risk group. To determine the adequacy of prophylaxis in this patient population, the prophylaxis used for each patient was compared with the ACCP 2001 guidelines. Each VTE case was classified as either preventable or nonpreventable based on the adequacy of the prophylaxis received. Patients with preventable VTE were those in whom adequate prophylaxis would have prevented VTE. Patients with nonpreventable VTE were those in whom adequate prophylaxis would not have prevented VTE.
Between June 2002 and May 2003, 44 patients at the Nassau University Medical Center (East Meadow, NY) received an objective diagnosis of VTE. The study group comprised 25 (56.8%) medical and 19 (43.1%) surgery patients. There were 29 (65.9%) patients with DVT, 17 (38.6%) patients with PE, and 2 (10.5%) patients with both forms of VTE. Most surgery patients were in the high-risk group (12 [63.2%]). There were no surgery patients in the low-risk group. Most patients (35 [79.5]) had three or fewer risk factors for VTE (
Table 1).
Of the 44 patients with VTE, 17 (38.6%) received inadequate prophylaxis (no prophylaxis at all, inadequate anticoagulation, or incorrect treatment with subcutaneous heparin but no mechanical device) according to the recommendations of the ACCP 2001 guidelines, and were therefore classified as having potentially preventable VTE. Twenty-seven (61.4%) patients were classified as having nonpreventable VTE after receiving prophylaxis in accordance with the ACCP 2001 guidelines. The incidents of VTE and the adequacy of prophylaxis received are summarized in
Table 2 by risk group. Most patients with VTE in the very-high-risk surgery group had not received adequate prophylaxis and, therefore, had potentially preventable VTE (4 of 5 patients; >αγϵδ 40 y with multiple VTE risk factors). In general, adequate VTE prophylaxis rates were lower among surgery patients compared with medical patients (52.6% vs 68%, respectively).
Table 3 presents the details of VTE cases in which VTE prophylaxis was considered inadequate. Six (14%) patients received no prophylaxis, 7 (16%) patients were ordered sequential thromboembolic deterrent stockings but received no anticoagulation therapy, 2 (5%) patients received inferior vena cava filters with either heparin or sequential thromboembolic deterrent stockings but did not receive adequate anticoagulation, and 2 (5%) patients received subcutaneous heparin with no mechanical device.
Patients and their VTE risk factors are further described in
Table 4. The prevalence of VTE risk factors was similar in the potentially preventable and nonpreventable categories, with the exception of surgery, which was more common in the preventable category, and central venous catheter lines, which was more common in the nonpreventable category. The most common risk factor in both categories was immobility. Other common risk factors included surgery, trauma, and cancer.
Figure 1 lists risk factors that are commonly overlooked.
The main finding of this study was that a substantial proportion of patients with risk factors for VTE and for whom VTE prophylaxis was indicated had not received prophylaxis in line with the ACCP 2001 guidelines. Had adequate prophylaxis been given, those cases of VTE might have been prevented. In most of the preventable VTE cases, inadequate prophylaxis was a result of the failure of surgeons to prescribe appropriate anticoagulation therapy. Other researchers have reported underuse of VTE prophylaxis in at-risk patients and suboptimal compliance with evidence-based guidelines on prophylaxis for VTE.
5–9,15–17 Arnold et al
7 reported that the proportion of patients with VTE who received inadequate prophylaxis despite clinical indications was as high as 68%. In a cross-sectional study of 397 patients admitted to a teaching hospital, Vallano et al
9 found that adherence to VTE prophylaxis guidelines according to patient risk factors was only 42%. Adherence to guidelines was shown to be higher in the surgical and critical care departments compared with the emergency and medical departments. In contrast, we found that VTE prophylaxis rates were generally lower among surgery patients than among medical patients (52% vs 68%). In particular, 80% of the very-high-risk surgery patients had not received adequate VTE prophylaxis.
A large number of patients (27 [61.4%]) in our study developed VTE despite receiving prophylaxis in line with the ACCP 2001 guidelines. Other studies have reported similar findings, and the incidence has been shown to vary according to the indication for prophylaxis.
18
The most common VTE risk factors in our study patients were cancer, immobility, surgery or trauma. In the study by Vallano et al,
9 the prevalence of certain VTE risk factors—namely, cancer, immobility, and obesity—was shown to be greater in the preventable VTE group compared with the nonpreventable VTE group. With the exception of surgery and central venous catheter lines, we did not see any differences in the prevalence of VTE risk factors between the two groups.
A comprehensive review of the literature has identified a number of barriers to physician adherence to clinical practice guidelines in general,
10 including a lack of awareness or agreement with the recommendations, or a lack of outcome expectancy. With regard to the ACCP 2001 guidelines, a 2002 a survey of physicians across three medical centers in Seattle demonstrated a lack of basic knowledge regarding the current treatment standards for VTE, indicating the need for further education aimed at increasing physician knowledge and awareness of the current guidelines.
12
Our study is limited by the small number of patients and the lack of statistical analysis. It should also be noted that in some preventable VTE cases, adequate prophylaxis may not have been received as a result of individual patient variables not investigated in this study. Preliminary data suggest that the implementation of the VTE prevention form (
Figure 2) created by the lead author (K.J.S.) and used at Nassau University Medical Center has contributed to a substantial decrease in the number of cases of hospital-acquired DVT and PE since its implementation in July 2005 (
Appendix).
We have found that during an 11-month period at the Nassau University Medical Center, a substantial proportion of patients with a diagnosis of VTE and with indications for VTE prophylaxis had not received prophylaxis in accordance with the ACCP 2001 guidelines. It is possible that, with adequate prophylaxis, these VTE cases would have been prevented. However, the incidence of VTE despite the use of adequate prophylaxis suggests the need for a reevaluation of the current guidelines. In addition, further efforts must be made to educate physicians about the current guidelines. Auditing of current practices may be a useful tool to assist in physician education.