Duplex ultrasonography for the detection of deep vein thrombi after total hip or knee arthroplasty

The rate of missed diagnosis of lower-limb DVT by ultrasound amounts to 50% or so in patients without symptoms of DVT: A meta-analysis

BACKGROUND

To assess whether the ultrasound (US) is a reliable approach in detecting lower-limb deep-vein thrombosis (DVT) in patients without symptoms of DVT.

METHODS

The research team performed a systematic search in PubMed, Ovid, Cochrane, and Web of Science without language or date restrictions. Full-text reports on prospective diagnostic studies involve the detection of lower-limb proximal and distal DVT in patients without symptoms of DVT using US and venography. A meta-analysis was performed using Meta-DiSc (version 1.4), providing the pooled sensitivity, specificity, positive (LR+) and negative (LR-) likelihood ratios of the detection accuracy of US. There were 4 different classes of subgroup analysis-the class of patients stratified by location of US exam (proximal, distal, whole leg), the class stratified by technique (color/doppler, compression, both modalities), the class stratified by kind of surgery (orthopedic, otherwise hospitalized) and the class stratified by era of publishing (1980s, 1990s, 2000s). The study quality and the risk of bias were evaluated using QUADAS-2, with heterogeneity was assessed and quantified by the Q score and I statistics, respectively.

RESULTS

The meta-analysis included 26 articles containing 41 individual studies with a total of 3951 patients without symptoms of DVT. Using venography as the gold standard, US for proximal DVT had a pooled sensitivity of 59% (95% confidence interval (CI) = 51%-66%) and a pooled specificity of 98% (95% CI = 97%-98%), US for distal DVT had a poor sensitivity of 43% (95% CI = 38%-48%) and a pooled specificity of 95% (95% CI = 94%-96%), US for whole-leg DVT had a pooled sensitivity of 59% (95% CI = 54%-64%) and a pooled specificity of 95% (95% CI = 94%-96%), US for post-major orthopedic surgery patients had a pooled sensitivity of 52% (95% CI = 49%-55%), and US for other types of patients had a pooled sensitivity of 58% (95% CI = 43%-72%). Pure compression technique for DVT had a poor sensitivity of 43% (95% CI = 39%-48%), pure color/doppler technique for DVT had a pooled sensitivity of 58% (95% CI = 53%-63%), compression and color/doppler technique for DVT had a pooled sensitivity of 61% (95% CI = 48%-74%).

CONCLUSION

US could be a useful tool for diagnosing DVT, but it has a lower positive rate and a higher false negative rate. The rate of missed diagnosis of lower-limb DVT by US amounts to 50% or so in the patients without symptoms of DVT. The negative results do not preclude the possibility of DVT and if appropriate heightened surveillance and continued monitoring or try a more accurate inspection method is warranted. The whole leg evaluation and color/doppler technique should be the preferred approach.

Outcome of Direct Oral Anticoagulant Treatment for Acute Lower Limb Deep Venous Thrombosis After Total Knee Arthroplasty Or Total Hip Arthroplasty

Objective: The aim of this study was to examine the treatment outcomes of edoxaban and apixaban on deep venous thrombosis (DVT) in Japanese patients undergoing total knee arthroplasty (TKA) or total hip arthroplasty (THA). Methods: We examined 100 patients receiving edoxaban or apixaban to treat lower limb DVT. The primary efficacy outcome was defined as the disappearance of DVT at three months post-treatment. The primary safety outcome was the change in hemoglobin (Hb) value after two and seven days of treatment compared with baseline, which was the start of treatment with edoxaban or apixaban. Results: The primary efficacy outcome occurred in 61 of the 70 patients (87.1%) in the edoxaban group and in 28 of the 30 patients (93.3%) in the apixaban group. There was no significant difference between the edoxaban and apixaban groups in the disappearance of DVT at three months (p = .497). The change in Hb value from baseline to two days post-treatment was -0.53 ± 0.98 in the edoxaban group and -0.06 ± 0.75 in the apixaban group (p = .010). At seven days post-treatment, the changes in Hb were -0.03 ± 1.60 and 0.30 ± 0.68 (p = .007) in the edoxaban and apixaban groups, respectively. Conclusion: Edoxaban and apixaban were equivalent in efficacy. However, apixaban was superior to edoxaban in terms of the change in Hb value. In cases of major bleeding, both edoxaban and apixaban need to be used carefully when treating DVT.

Early Experience with the Sydney and EVT Prostheses for Endoluminal Treatment of Abdominal Aortic Aneurysms

Purpose:

The aim of this study was to report early experiences with the Sydney and Endovascular Technologies (EVT) prostheses for the treatment of abdominal aortic aneurysms (AAA) deemed suitable for endoluminal tube graft repair.

Methods:

Consecutive endoluminal tube graft repairs were analyzed over the first 12 months in which the Sydney and EVT prostheses were used. Patients eligible for the EVT prosthesis had type I AAAs: a proximal neck length ≥ 2 cm, a distal cuff length ≥ 1.5 cm, and nontortuous iliac arteries ≥ 8 mm. Selection criteria for the Sydney device were more liberal and included AAAs that had distal cuffs < 1.5 cm. During the study period, 28 of 91 patients evaluated for AAA repair were thus selected for endoluminal grafting: 18 patients received the Sydney endograft and 10 the EVT device. Medical comorbidities were present in slightly less than one third of patients in both groups. Contrast-enhanced computerized tomography (CT) was performed preoperatively, within 10 days of operation, and at 6 and 12 months postprocedure.

Results:

All endografts were successfully deployed in both groups. Postprocedural CT scans revealed incomplete aneurysm exclusion in four patients with the Sydney endograft. Subsequent deployment of a second endograft sealed these “leaks” in two cases; the other two were converted to open repair (89% clinical success). No leaks were seen with the EVT device. Local/vascular complications occurred in 33% of the Sydney group compared with 20% for the EVT device (p = 0.001); systemic sequelae were more common in the EVT group (30% versus 17% in the Sydney cohort, p = 0.002). There were no deaths within 30 days; three late deaths were not procedure related.

Conclusion:

AAAs that are suitable for endoluminal tube graft repair may be treated with a high rate of initial success with either the Sydney or EVT prostheses. More liberal selection criteria may increase the likelihood of local/vascular complications.

Endoluminal Grafting of Abdominal Aortic Aneurysms: Causes of Failure and Their Prevention

Purpose:

The aim of this study was to analyze the causes of failure of endoluminal grafting for abdominal aortic aneurysms (AAA) and to put forward proposals for preventing these failures.

Methods:

Since May 1992, endoluminal repair of aneurysms was undertaken in 47 patients. Forty-three of these patients had AAAs and are the basis of this study. All procedures were nonurgent and were performed in the operating room with the patient draped for an open repair in the event of failed endoluminal repair. Radiographic guidance was used to pass the endografts into the aorta via a delivery sheath introduced through the femoral or iliac arteries. The configuration of the endografts was tubular (n = 28), tapered aortoiliac/aorto-femoral (n = 11), and bifurcated (n = 4).

Results:

Successful endoluminal repair was achieved in 34 of 43 (79%) patients. The remaining nine were terminated in favor of an open repair. The causes of failure were problems with access (2), balloon malfunction (1), stent dislodgment (3), graft thrombosis (1), and inability to deploy the contralateral limb of a bifurcated graft (2). All failed endoluminal repairs proceeded to successful open repair. There was no perioperative mortality in patients undergoing endoluminal repair or in those whose endoluminal repair was converted to open operation.

Conclusions:

The failures of endoluminal grafting have been analyzed. Methods of avoiding access problems, balloon malfunction, and stent dislodgment have been defined and recommendations made.

Deep vein thrombosis after total hip arthroplasty in Korean patients and D-dimer as a screening tool

INTRODUCTION

This prospective study was designed to confirm risk factors and to assess the incidence of deep vein thrombosis after total hip and surface replacement arthroplasty in Korean patients not receiving anticoagulation prophylaxis and to determine efficacy of plasma D-dimer levels as a screening test.

MATERIALS AND METHODS

From May 2003 to August 2004, 221 consecutive patients undergoing unilateral total hip arthroplasty and hip resurfacing were evaluated. All patients underwent ultrasonography preoperatively and venography and/or ultrasonography on postoperative day 7. Plasma D-dimer levels were estimated by latex immuno-assay preoperatively and on days 3 and 7 postoperatively.

RESULTS

Of the 221 patients in our cohort, 23 developed deep vein thrombosis (10.4%). Age (r = 0.245, P < 0.001) and gender (r = 0.155, P = 0.021) significantly correlated with deep vein thrombosis. Rise in incidence paralleled increase in age (X(2) = 32.860, P < 0.001). D-dimer levels on postoperative days 3 (gamma = 0.364, P < 0.001) and 7 (gamma = 0.470, P < 0.001) were significantly correlated to the development of DVT.

CONCLUSION

While incidence of deep vein thrombosis in Korean population after THA was lower than that in the West; it increased with age, and in female gender. Significant correlation was found between D-dimer levels and the development of deep vein thrombosis.

Evaluation of deep vein thrombosis with multidetector row CT after orthopedic arthroplasty: a prospective study for comparison with Doppler sonography

Objective

This prospective study evaluated the ability of indirect 16-row multidetector CT venography, in comparison with Doppler sonography, to detect deep vein thrombosis after total hip or knee replacement.

Materials and Methods

Sixty-two patients had undergone orthopedic replacement surgery on a total of 30 hip joints and 54 knee joints. The CT venography (scan delay time: 180 seconds; slice thickness/increment: 2/1.5 mm) and Doppler sonography were performed 8 to 40 days after surgery. We measured the z-axis length of the beam hardening artifact that degraded the image quality so that the presence of deep vein thrombosis couldn't be evaluated on the axial CT images. The incidence and location of deep vein thrombosis was analyzed. The diagnostic performance of the CT venograms was evaluated and compared with that of Doppler sonography as a standard of reference.

Results

The z-axis length (mean±standard deviation) of the beam hardening artifact was 4.5 ± 0.8 cm in the arthroplastic knees and 3.9 ± 2.9 cm in the arthroplastic hips. Deep vein thrombosis (DVT) was found in the popliteal or calf veins on Doppler sonography in 30 (48%) of the 62 patients. The CT venography has a sensitivity, specificity, positive predictive value, negative predictive value and accuracy of 90%, 97%, 96%, 91% and 94%, respectively.

Conclusion

The ability of CT venography to detect DVT was comparable to that of Doppler sonography despite of beam hardening artifact. Therefore, CT venography is feasible to use as an alternative modality for evaluating postarthroplasty patients.

The Effect of a Computerized Reminder System on the Prevention of Postoperative Venous Thromboembolism

STUDY OBJECTIVE

To measure the effect of an altered process of care, directed by a computerized reminder system, on rates of symptomatic postoperative venous thromboembolism.

DESIGN

Comparisons of preintervention and postintervention measurements.

SETTING

A university-affiliated community hospital in Utah.

PATIENTS

Two-thousand seventy-seven consecutive patients who underwent major operations in four surgical divisions between January 1, 1997, and October 31, 1997 (preintervention), and 2,093 consecutive patients who underwent the same procedures between January 1, 1998, and October 31,1998 (postintervention).

INTERVENTION

A program to prevent venous thromboembolism developed from American College of Chest Physicians guidelines, and an altered work process directed by a computerized reminder system.

MEASUREMENTS

Rates of symptomatic, objectively confirmed deep vein thrombosis (DVT), pulmonary embolism (PE), and death attributable to venous thromboembolism occurring within 90 days of the date of surgery.

RESULTS

The preintervention and postintervention cohorts did not differ with respect to age, severity of illness, number of risk factors for venous thromboembolism, or individual risk factors for venous thromboembolism. The overall prophylaxis rate increased from 89.9% before implementation of the computerized reminder system to 95.0% after implementation (p < 0.0001). The combined 90-day rate of symptomatic DVT, PE, and death attributable to PE remained the same (preintervention, 1.0%; postintervention, 1.2%; odds ratio, 1.21; 95% confidence interval, 0.67 to 2.20). Forty of 46 venous thromboembolic complications (87%) occurred despite the delivery of American College of Chest Physicians-recommended measures to prevent venous thromboembolism.

CONCLUSIONS

Computerized reminder systems combined with altered care procedures increase the rate of prophylaxis against venous thromboembolism without decreasing the rate of symptomatic venous thromboembolism when the baseline rate of prophylaxis is high. A population of surgical patients exists who are resistant to American College of Chest Physicians-recommended prophylactic measures against venous thromboembolism. New strategies are needed to address prophylaxis-resistant venous thromboembolism.

Extended Lower Limb Venous Ultrasound for the Diagnosis of Proximal and Distal Vein Thrombosis in Asymptomatic Patients after Total Hip Replacement

OBJECTIVE

To assess the performance of extended lower limb venous ultrasound (US) for the diagnosis of asymptomatic deep vein thrombosis (DVT) and to estimate a 3-month DVT incidence on repeated US after total hip replacement.

DESIGN

Diagnostic performance study and prospective cohort study.

MATERIALS AND METHODS

US was compared to phlebography in 70 consecutive patients and interobserver agreement was assessed in the last 48 patients at day 8. US was repeated in these 48 patients at day 13 and day 90.

RESULTS

Phlebography demonstrated a DVT in 18/70 (26%) patients, with five proximal and 13 distal and US in 23/70 (33%) patients, with eight proximal and 15 distal. Sensitivity and specificity of US with 95% CI were 94% (73-100) and 89% (76-96), respectively. Sensitivity in isolated distal vein thrombosis was 92% (67-99). The Kappa coefficient for agreement between observers was 0.84 (0.66-1.00). Follow-up showed a DVT in 15/48 (31%) patients on day 8, in 20/48 patients (42%) on day 13. DVT recurred in two patients during follow-up.

CONCLUSIONS

The incidence of asymptomatic DVT is still significant despite prophylaxis but most DVTs remain distal and occur in the first 2 weeks. Extended US could replace phlebography for systematic screening in clinical trials using surrogate endpoints in view of its high accuracy and reliability.

A systematic review of the accuracy of ultrasound in the diagnosis of deep venous thrombosis in asymptomatic patients

Evaluation of the accuracy of ultrasound has yielded heterogeneous results. Our objective was to summarize the evidence on the accuracy of ultrasound compared to venography in asymptomatic patients, taking into account the variation due to threshold differences. Searches of journal table of contents, computer databases (Medline, Embase, Biomed, Cochrane) and conference proceedings were performed. A study was eligible if it prospectively compared ultrasound to venography for the diagnosis of DVT in asymptomatic patients. Data of studies selected for inclusion were extracted independently by two authors. High quality studies with consecutive patient enrollment, blind evaluation of the two techniques, and absence of verification bias are summarized as Level 1, while those not fulfilling one or more of these criteria are considered Level 2. Original study authors were contacted to confirm accuracy and to provide missing data. A pooled estimate of the accuracy of ultrasound was obtained according to the method of Moses and coworkers. This method gives a summary diagnostic odds ratio (DOR). The DOR is a single indicator of test performance. It varies between 0 and infinity and exceeds 1, only when ultrasound is more often positive in patients with DVT relative to those without DVT. Higher DOR indicates better discriminatory test performance. Thirty one studies were rated as potentially unbiased and graded as Level 1. The mean prevalence of DVT as determined by venography was 22%. In Level 1 studies, the odds of positive ultrasound in proximal veins was 379 times higher (95% confidence limits 65, 2,200) and in distal veins 32 times higher (7.5, 135) among patients with DVT than those without. Our results suggest that, particularly for proximal veins, ultrasound is accurate for the diagnosis of DVT in asymptomatic postoperative orthopedic patients. More research is needed in other clinical settings.

Surveillance for venous thromboembolic disease after total knee arthroplasty

The value of deep venous thrombosis screening after total knee arthroplasty is controversial. The purpose of the current study was to examine the value of routine surveillance for venous thrombosis after total knee arthroplasty done with modern operative and perioperative treatment. Computerized search engines were used to identify papers published between 1985 and July 2000 relevant to the purpose of the study. Papers that met the inclusion criteria for review were categorized as follows: the frequency of deep venous thrombosis; the natural history of deep venous thrombosis; the accuracy of screening methods for venous thrombosis; and efficacy of screening in reducing morbidity attributable to venous thromboembolism after total knee arthroplasty. Several studies have shown a low complication rate related to venous thromboembolic disease when compression ultrasound is used for screening as part of a clinical algorithm after knee arthroplasty. However, the only large prospective randomized trial evaluating ultrasound screening failed to show a reduction in morbidity with a surveillance protocol. The benefits of surveillance depend on factors specific to each surgeon's practice including the type and duration of venous prophylaxis, the rate of symptomatic and asymptomatic thromboembolic disease associated with that protocol, and the accuracy of screening tests used for surveillance.

Does venous microemboli detection add to the interpretation of D-dimer values following orthopedic surgery?

The identification of risk factors for deep venous thrombosis (DVT) following orthopedic surgery remains unclear. We have investigated the relationship between plasma levels of D-dimer (DD), the presence or absence of microemboli 1 day after surgery, and the occurrence of DVT 7 days after total hip or knee replacement. The prevalence of DVT was 25 (13.3%) among 188 patients and was lower in 112 patients with DD < 2808 ng mL(-1) than in the 56 patients with higher DD levels: respectively, 8.0% vs. 21.4% (p < 0.05). D-dimer is not suitable for individual estimation of DVT risk. Microemboli were found in 112 (60%) of 186 subjects. The presence/absence or the frequency of the microemboli showed no relationship with the occurrence of DVT. Last, when evaluating the risk of DVT in orthopedic surgery, microemboli detection does not add to the interpretation of DD concentration.

Diagnostic management of venous thromboembolism

The accuracy of diagnostic methods for the diagnosis of deep vein thrombosis and pulmonary embolism in symptomatic patients is critically reviewed. In addition, the safety of withholding anticoagulant therapy from patients with suspected deep vein thrombosis or pulmonary embolism in whom the qualified diagnostic strategy was normal is evaluated by determining the frequency of venous thromboembolic complications during 3 months of follow-up. It is shown that the currently used available diagnostic techniques for deep vein thrombosis are all able to identify the majority of patients who indeed have venous thrombosis. However, as result of its accuracy and practical advantages, compression ultrasound is the test of choice in the evaluation of symptomatic patients. Patients with a normal test outcome should be re-tested to detect the small proportion of patients with proximally extending calf vein thrombosis. In the strategy of repeated diagnostic testing, impedance plethysmography could be used as an alternative to ultrasonography. To obtain a reduction in repeat tests various diagnostic strategies have been evaluated and it was shown that these strategies, using non-invasive tests, can be as accurate and safe as the invasive reference strategy. The safeties of the various strategies were very similar; however, important differences were observed with respect to the practical implementation of the various diagnostic strategies. Simplification of the repeated testing strategy by using a D-dimer assay and/or a clinical decision rule seems to be promising. The reference standard for the diagnosis of pulmonary embolism remains pulmonary angiography. Several strategies based on non-invasive diagnostic methods have been evaluated for their safety and complexability. Perfusion-ventilation lung scanning is the most thoroughly evaluated non-invasive technique so far. It seems safe to withhold anticoagulant therapy in patients suspected of pulmonary embolism with a normal perfusion lung scan result; however, further testing is needed in the case of a non-diagnostic perfusion-ventilation lung scan result. At this moment angiography is the method of choice in this category of patients. D-dimer assays, clinical decision rules and ultrasound examinations of the legs seem to have a high potential to limit the need for angiography. Also, spiral computerized tomography and magnetic resonance imaging are promising techniques, but their role in the diagnostic management of pulmonary embolism is still uncertain.

Ultrasound surveillance for asymptomatic deep venous thrombosis after total joint replacement

Prospective data on 202 consecutive patients who had a total of 123 total hip and ninety-four total knee arthroplasties were collected from two university medical centers. The findings of routine surveillance for deep venous thrombosis performed with ascending contrast venography were compared with those of surveillance with duplex ultrasonography complemented with color-flow Doppler imaging. All of the studies were performed between the third and seventh postoperative days. Of the 202 patients (342 extremities) who were examined, fifty-five (27 per cent) were found to have deep venous thrombosis; fifty-two (95 per cent) of the thrombi were in the calf and three (5 per cent) were in the proximal veins. All of the thrombi were clinically asymptomatic and all were nonocclusive, allowing passage of contrast medium around an intraluminal filling defect. Duplex ultrasonography with color-flow Doppler imaging correctly identified two of the three proximal thrombi and five of the fifty-two thrombi in the calf (sensitivity, 10 per cent). The sensitivity for the detection of thrombi in the calf was zero of sixteen at one of the institutions involved in the study and 14 per cent (five of thirty-six) at the other. There were two false-positive findings on ultrasonographic examination; one involved a proximal thrombus and one, a distal thrombus. We believe that the interinstitutional variability and insensitivity of duplex ultrasonography with color-flow Doppler imaging for the detection of asymptomatic deep venous thrombi in the calf after total joint replacement make it unreliable as a routine surveillance tool after total hip or knee arthroplasty.

Intercondylar distal femoral fracture. An unreported complication of posterior-stabilized total knee arthroplasty

In an attempt to study the incidence of intraoperative femoral intercondylar fractures, two large series of posterior-stabilized total knee arthroplasty (TKA) systems were reviewed. Eight hundred ninety-eight nonconsecutive primary posterior-stabilized TKAs were compared with a second nonconsecutive series of 532 posterior-stabilized TKAs. Unique to the secondary TKA system is an intercondylar sizing guide to aid in verification of the intercondylar resection size. In the initial series, 40 distal femoral intercondylar fractures were noted (rate = 1:22; nondisplaced, 35; displaced, 5). In the secondary series, one displaced distal femoral intercondylar fracture occurred (rate = 1;532). The difference in the rate of fracture between the two populations was statistically significant (P<.001). Intraoperative distal femoral intercondylar fracture represents a potential complication of TKA and can be avoided with careful resection technique and size verification. No change in the postoperative rehabilitation program is required, however, for those patients identified with nondisplaced and intraoperative-stabilized displaced distal femoral intercondylar fractures.

Utility of leg ultrasonography in suspected symptomatic isolated calf deep venous thrombosis

PURPOSE

To evaluate the utility of duplex ultrasonography in patients with suspected symptomatic, isolated calf deep venous thrombosis.

PATIENTS AND METHODS

Thirty patients with clinically suspected isolated calf deep venous thrombosis were examined with both duplex ultrasonography and contrast venography and the results were compared.

RESULTS

Venography detected 7 cases of isolated calf deep venous thrombosis, all of which were also detected by ultrasonography. Ultrasound identified an additional 3 cases of soleal vein thrombosis, but venography did not visualize these veins. Of the 20 negative ultrasound studies, 11 were technically inadequate; however, no false-negative ultrasound studies were noted.

CONCLUSIONS

Compression ultrasonography may be reliable for the evaluation of patients with suspected symptomatic infrapopliteal deep venous thrombosis. Its apparent superiority to contrast venography in visualizing muscular calf veins warrants further study; however, the high rate of technical inadequacy in ultrasound studies observed here, if confirmed in larger studies, may limit the usefulness of ultrasound in this setting.

A prospective study of venous thromboembolism after major trauma

BACKGROUND

Although deep-vein thrombosis and pulmonary embolism are considered common complications after major trauma, their frequency and the associated risk factors have not been carefully quantified.

METHODS

We performed serial impedance plethysmography and lower-extremity contrast venography to detect deep-vein thrombosis in a cohort of 716 patients admitted to a regional trauma unit. Prophylaxis against thromboembolism was not used.

RESULTS

Deep-vein thrombosis in the lower extremities was found in 201 of the 349 patients (58 percent) with adequate venographic studies, and proximal-vein thrombosis was found in 63 (18 percent). Three patients died of massive pulmonary embolism before venography could be performed. Before venography, only three of the patients with deep-vein thrombosis had clinical features suggestive of the condition. Deep-vein thrombosis was found in 65 of the 129 patients with major injuries involving the face, chest, or abdomen (50 percent); in 49 of the 91 patients with major head injuries (53.8 percent); in 41 of the 66 with spinal injuries (62 percent); and in 126 of the 182 with lower-extremity orthopedic injuries (69 percent). Thrombi were detected in 61 of the 100 patients with pelvic fractures (61 percent), in 59 of the 74 with femoral fractures (80 percent), and in 66 of the 86 with tibial fractures (77 percent). A multivariate analysis identified five independent risk factors for deep-vein thrombosis: older age (odds ratio, 1.05 per year of age; 95 percent confidence interval, 1.03 to 1.06), blood transfusion (odds ratio, 1.74; 95 percent confidence interval, 1.03 to 2.93), surgery (odds ratio, 2.30; 95 percent confidence interval, 1.08 to 4.89), fracture of the femur or tibia (odds ratio, 4.82; 95 percent confidence interval, 2.79 to 8.33), and spinal cord injury (odds ratio, 8.59; 95 percent confidence interval, 2.92 to 25.28).

CONCLUSIONS

Venous thromboembolism is a common complication in patients with major trauma, and effective, safe prophylactic regimens are needed.

RD heparin compared with warfarin for prevention of venous thromboembolic disease following total hip or knee arthroplasty. RD Heparin Arthroplasty Group

The efficacy and safety of RD heparin, a low-molecular-weight heparin, for the prevention of venous thromboembolic disease among patients managed with an elective total hip or total knee arthroplasty were compared with the efficacy and safety of warfarin in an open-label prospective, multicenter trial. Patients were randomized to receive either a fixed dose of fifty anti-factor-Xa units of RD heparin per kilogram of body weight, administered subcutaneously twice daily, beginning postoperatively; a fixed dose of ninety anti-factor-Xa units of RD heparin per kilogram of body weight, administered subcutaneously once daily, beginning postoperatively; or five milligrams of warfarin, administered orally preoperatively, followed by a daily adjusted dose of warfarin to prolong the prothrombin time ratio to 1.2 to 1.5. The primary measure of efficacy was contrast venography of the treated limb, performed by local radiologists blinded to the type of treatment that had been assigned. Nine hundred and sixty-nine patients had a complete assessment for the presence of deep-vein thrombosis. The over-all rates of venous thromboembolic disease were 16 percent (95 pecent confidence interval, 13 to 21 percent) (fifty-three) for the 328 patients who received RD heparin twice daily, 21 percent (95 percent confidence interval, 17 to 26 percent) (sixty-eight) for the 320 patients who received RD heparin once daily, and 27 percent (95 percent confidence interval, 22 to 32 percent) (eighty-seven) for the 321 patients who received warfarin (p < 0.001 for RD heparin administered twice daily compared with warfarin; p = 0.13 for RD heparin administered once daily compared with warfarin). Compared with warfarin, RD heparin administered twice daily and RD heparin administered once daily reduced the risk of venous thromboembolic disease by 41 percent (95 percent confidence interval, 20 to 56 percent) and 18 percent (95 percent confidence interval, -6 to 37 percent), respectively. The rates of venous thromboembolic disease after 523 total hip arthroplasties were 8, 14, and 14 percent for the patients who received RD heparin twice daily, those who received it once daily, and those who received warfarin (p = 0.07 for RD heparin administered twice daily compared with warfarin; p = 0.82 for RD heparin administered once daily compared with warfarin).(ABSTRACT TRUNCATED AT 400 WORDS)