The association between anticoagulation and adverse outcomes after a positive SARS-CoV-2 test among older outpatients: A population-based cohort study

Introduction

Anticoagulation may improve outcomes in patients with COVID-19 when started early in the course of illness.

Materials and methods

This was a population-based cohort study using linked administrative datasets of outpatients aged ≥65 years old testing positive for SARS-CoV-2 between January 1 and December 31, 2020 in Ontario, Canada. The key exposure was anticoagulation with warfarin or direct oral anticoagulants before COVID-19 diagnosis. We calculated propensity scores and used matching weights (MWs) to reduce baseline differences between anticoagulated and non-anticoagulated patients. The primary outcome was a composite of death or hospitalization within 60 days of a positive SARS-CoV-2 test. We used the Kaplan-Meier method and cumulative incidence functions to estimate risk of the primary and component outcomes at 60 days.

Results

We studied 23,159 outpatients (mean age 78.5 years; 13,474 [58.2%] female), among whom 3200 (13.8%) deaths and 3183 (13.7%) hospitalizations occurred within 60 days of the SARS-CoV-2 test. After application of MWs, the 60-day risk of death or hospitalization was 29.2% (95% CI 27.4%–31.2%) for anticoagulated individuals and 32.1% (95% CI 30.7%–33.5%) without anticoagulation (absolute risk difference [ARD], −2.9%; p = 0.005). Anticoagulation was also associated with a lower risk of death: 18.6% (95% CI 17.0%–20.2%) with anticoagulation and 20.9% (95% CI 19.7%–22.2%) in non-anticoagulated patients (ARD -2.3%; p = 0.005).

Conclusions

Among outpatients aged ≥65 years, oral anticoagulation at the time of a positive SARS-CoV-2 test was associated with a lower risk of a composite of death or hospitalization within 60 days.

Guidance for Health Care Leaders During the Recovery Stage of the COVID-19 Pandemic: A Consensus Statement

IMPORTANCE

The COVID-19 pandemic is the greatest global test of health leadership of our generation. There is an urgent need to provide guidance for leaders at all levels during the unprecedented preresolution recovery stage.

OBJECTIVE

To create an evidence- and expertise-informed framework of leadership imperatives to serve as a resource to guide health and public health leaders during the postemergency stage of the pandemic.

EVIDENCE REVIEW

A literature search in PubMed, MEDLINE, and Embase revealed 10 910 articles published between 2000 and 2021 that included the terms leadership and variations of emergency, crisis, disaster, pandemic, COVID-19, or public health. Using the Standards for Quality Improvement Reporting Excellence reporting guideline for consensus statement development, this assessment adopted a 6-round modified Delphi approach involving 32 expert coauthors from 17 countries who participated in creating and validating a framework outlining essential leadership imperatives.

FINDINGS

The 10 imperatives in the framework are: (1) acknowledge staff and celebrate successes; (2) provide support for staff well-being; (3) develop a clear understanding of the current local and global context, along with informed projections; (4) prepare for future emergencies (personnel, resources, protocols, contingency plans, coalitions, and training); (5) reassess priorities explicitly and regularly and provide purpose, meaning, and direction; (6) maximize team, organizational, and system performance and discuss enhancements; (7) manage the backlog of paused services and consider improvements while avoiding burnout and moral distress; (8) sustain learning, innovations, and collaborations, and imagine future possibilities; (9) provide regular communication and engender trust; and (10) in consultation with public health and fellow leaders, provide safety information and recommendations to government, other organizations, staff, and the community to improve equitable and integrated care and emergency preparedness systemwide.

CONCLUSIONS AND RELEVANCE

Leaders who most effectively implement these imperatives are ideally positioned to address urgent needs and inequalities in health systems and to cocreate with their organizations a future that best serves stakeholders and communities.

Prevention of Deep Vein Thrombosis after Major Knee Surgery - A Randomized, Double-Blind Trial Comparing a Low Molecular Weight Heparin Fragment (Enoxaparin) to Placebo

Consecutive patients undergoing knee arthroplasty or tibial osteotomy at four participating hospitals received either enoxaparin, 30 mg subcutaneously every 12 h (n = 66) or an identicalappearing placebo (n = 65). All study medications started the morning after the operation and were continued up to a maximum of 14 days. Patients underwent surveillance with 125I-fibrinogen leg scanning and impedance plethysmography. Bilateral contrast venography was performed routinely at Day 14 or at time of discharge, if sooner. Deep vein thrombosis was detected by venography in 35 of 54 patients (65%) in the placebo group and in 8 of 41 patients in the enoxaparin group (19%), a risk reduction of 71%, P <0.0001. For the entire study group, deep vein thrombosis was detected by either venography of non-invasive tests in 37 of 64 patients (58%) in the placebo group and in 11 of 65 patients (17%) in the enoxaparin group, a risk reduction of 71%, P <0.0001. Proximal vein thrombosis was found in 19% of the placebo patients and in none of the enoxaparin patients, a risk reduction of 100%, P <0.001. Bleeding complications occurred in 5 of 65 patients (8%) in the placebo group and in 4 of 66 patients (6%) in the enoxaparin group, P = 0.71. There were no differences in the amount of blood loss, minimum hemoglobin levels and number of units of packed red cells given between the two treatment groups. We conclude that a fixed dose regimen of enoxaparin, started post-operatively, is an effective and safe regimen for reducing the frequency of deep vein thrombosis after major knee surgery.

Development and evaluation of a continuing pharmacy education (CPE) program in thrombosis management

BACKGROUND AND PURPOSE

A continuing education (CE) course in thrombosis management for pharmacists was developed through the Office of Continuing Professional Development (CPD) at the University of Toronto to address pharmacists' needs for the knowledge and skills to provide care to patients receiving anticoagulants. This article describes the development of the course as well as the evaluation designed to assess its impact on pharmacists' knowledge, attitudes, and changes in practice.

EDUCATIONAL ACTIVITY AND SETTING

A three-day course was developed. Outcomes were evaluated using a feedback questionnaire, pre- and post-session quizzes and semi-structured interviews conducted six months after course completion. Participant satisfaction, knowledge acquisition and perceived change in knowledge, skills and practice were evaluated.

FINDINGS

Thirty-seven pharmacists enrolled in the program, 21 of whom participated in a semi-structured interview. More than 90% reported that the program exceeded their expectations. Pharmacists' knowledge in thrombosis care improved significantly after each day of the course. Participants felt the greatest benefits of the program were increases in knowledge and confidence and the opportunity to network. The case-based discussions and practical tips gained from experts and peers were highly ranked. Participants strongly agreed that they were applying what they learned in the course to clinical practice, and they provided numerous examples of how their practice changed because of the program.

DISCUSSION AND SUMMARY

The development of this CE course demonstrates application of best practices in continuing education. The evaluation of the program suggests that a CE course in thrombosis improves pharmacist knowledge, confidence and ability to incorporate what was learned into practice. This course design and evaluation can serve as a model for other CE courses for pharmacists as this field continues to grow and encourages thoughtful use of theoretical principles and well-designed evaluation for continual improvement of CE.

Venous Thromboembolism Prophylaxis in Liver Surgery

BACKGROUND

At a recently concluded Americas Hepato-Pancreato-Biliary Association Annual Meeting, a Clinical Practice Guidelines Conference Series was convened with the topic focusing on Venous Thromboembolism (VTE) Prophylaxis in Liver Surgery. The symposium brought together hepatobiliary surgeons from three continents as well as medical experts in hematology and coagulation.

METHODS

The content of the discussion included literature reviews, evaluation of multi-institutional VTE outcome data, and examination of practice patterns at multiple high-volume centers.

RESULTS

Literature review demonstrated that, within gastrointestinal surgery, liver resection patients are at particularly high-risk for VTE. Recent evidence clearly indicates a direct relationship between the magnitude of hepatectomy and postoperative VTE rates, however, the PT/INR does not accurately reflect the coagulation status of the post-hepatectomy patient. Evaluation of available data and practice patterns regarding the utilization and timing of anticoagulant VTE prophylaxis led to recommendations regarding preoperative and postoperative thromboprophylaxis for liver surgery patients.

CONCLUSIONS

This conference was effective in consolidating our knowledge of coagulation abnormalities after liver resection. Based on the expert review of the available data and practice patterns, a number of recommendations were developed.

Economic evaluation of the prophylaxis for thromboembolism in critical care trial (E-PROTECT): study protocol for a randomized controlled trial

Background

Venous thromboembolism (VTE) is a common complication of critical illness with important clinical consequences. The Prophylaxis for ThromboEmbolism in Critical Care Trial (PROTECT) is a multicenter, blinded, randomized controlled trial comparing the effectiveness of the two most common pharmocoprevention strategies, unfractionated heparin (UFH) and low molecular weight heparin (LMWH) dalteparin, in medical-surgical patients in the intensive care unit (ICU). E-PROTECT is a prospective and concurrent economic evaluation of the PROTECT trial.

Methods/Design

The primary objective of E-PROTECT is to identify and quantify the total (direct and indirect, variable and fixed) costs associated with the management of critically ill patients participating in the PROTECT trial, and, to combine costs and outcome results to determine the incremental cost-effectiveness of LMWH versus UFH, from the acute healthcare system perspective, over a data-rich time horizon of ICU admission and hospital admission. We derive baseline characteristics and probabilities of in-ICU and in-hospital events from all enrolled patients. Total costs are derived from centers, proportional to the numbers of patients enrolled in each country. Direct costs include medication, physician and other personnel costs, diagnostic radiology and laboratory testing, operative and non-operative procedures, costs associated with bleeding, transfusions and treatment-related complications. Indirect costs include ICU and hospital ward overhead costs. Outcomes are the ratio of incremental costs per incremental effects of LMWH versus UFH during hospitalization; incremental cost to prevent a thrombosis at any site (primary outcome); incremental cost to prevent a pulmonary embolism, deep vein thrombosis, major bleeding event or episode of heparin-induced thrombocytopenia (secondary outcomes) and incremental cost per life-year gained (tertiary outcome). Pre-specified subgroups and sensitivity analyses will be performed and confidence intervals for the estimates of incremental cost-effectiveness will be obtained using bootstrapping.

Discussion

This economic evaluation employs a prospective costing methodology concurrent with a randomized controlled blinded clinical trial, with a pre-specified analytic plan, outcome measures, subgroup and sensitivity analyses. This economic evaluation has received only peer-reviewed funding and funders will not play a role in the generation, analysis or decision to submit the manuscripts for publication.

Trial registration

Clinicaltrials.gov Identifier: NCT00182143. Date of registration: 10 September 2005.

Electronic supplementary material

The online version of this article (doi:10.1186/1745-6215-15-502) contains supplementary material, which is available to authorized users.

Symptomatic venous thromboembolism uncommon without thromboprophylaxis after isolated lower-limb fracture: the knee-to-ankle fracture (KAF) cohort study

BACKGROUND

The prevalence of deep vein thrombosis as demonstrated by routine venography in patients with distal lower-extremity injury requiring cast immobilization or surgery is 10% to 40%. These deep vein thromboses are usually asymptomatic and distal, and the need for thromboprophylaxis in these patients is not known.

METHODS

We conducted a multicenter prospective cohort study to define the prevalence of symptomatic venous thromboembolism in patients with a tibial, fibular, or ankle fracture (treated nonoperatively) or a patellar or foot fracture (treated operatively or conservatively). Consecutive patients were enrolled at five Ontario, Canada, hospitals within ninety-six hours after injury, and they were followed with a telephone interview at two, six, and twelve weeks. Thromboprophylaxis was not allowed. Suspected venous thromboembolism was investigated in a standardized manner.

RESULTS

From August 2002 to June 2005, 1200 patients were enrolled, and a three-month follow-up was completed for 98% of them. Eighty-two percent of the patients were treated with cast or splint immobilization for an average (and standard deviation) of 42 ± 32 days. Overall, seven patients (0.6%; 95% confidence interval [CI] = 0.2% to 1.2%) had symptomatic, objectively confirmed venous thromboembolism. Two of them had proximal deep vein thrombosis; three, calf deep vein thrombosis; and two, pulmonary embolism. There were no fatal pulmonary emboli.

CONCLUSIONS

Symptomatic venous thromboembolism is an infrequent complication after fractures of the distal part of the lower limb requiring cast immobilization and managed without thromboprophylaxis. Given these estimates of symptomatic venous thromboembolism, the risk-benefit ratio and cost-effectiveness of routine anticoagulant prophylaxis are unlikely to be favorable for these patients.

LEVEL OF EVIDENCE

Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

A pilot study of computed tomography-detected asymptomatic pulmonary filling defects after hip and knee arthroplasties

We asked what the incidence of asymptomatic filling defects is on routine multidetector computed tomography (MDCT) in primary hip (total hip arthroplasty [THA]) and knee arthroplasties (TKA) patients. We prospectively performed MDCT scans on the first postoperative day for THA (n = 21)/TKA (n = 27). Patients underwent routine postoperative care, and data were collected for symptoms such as tachycardia or shortness of breath. More patients undergoing TKA had positive computed tomography scans than those undergoing THA: 11 (41%) vs 1 (5%), respectively. All patients diagnosed with a filling defect were discharged from the hospital without treatment of symptomatic pulmonary embolism. Our study demonstrates a high rate of abnormal MDCT early after lower extremity arthroplasty, the clinical importance of which may be benign.

Economic analyses of venous thromboembolism prevention strategies in hospitalized patients: a systematic review

Introduction

Despite evidence-based guidelines for venous thromboembolism prevention, substantial variability is found in practice. Many economic evaluations of new drugs for thromboembolism prevention do not occur prospectively with efficacy studies and are sponsored by the manufacturers, raising the possibility of bias. We performed a systematic review of economic analyses of venous thromboembolism prevention in hospitalized patients to inform clinicians and policy makers about cost-effectiveness and the potential influence of sponsorship.

Methods

We searched MEDLINE, EMBASE, Cochrane Databases, ACP Journal Club, and Database of Abstracts of Reviews of Effects, from 1946 to September 2011. We extracted data on study characteristics, quality, costs, and efficacy.

Results

From 5,180 identified studies, 39 met eligibility and quality criteria. Each addressed pharmacologic prevention: low-molecular-weight heparins versus placebo (five), unfractionated heparin (12), warfarin (eight), one or another agents (five); fondaparinux versus enoxaparin (11); and rivaroxaban and dabigatran versus enoxaparin (two). Low-molecular-weight heparins were most economically attractive among most medical and surgical patients, whereas fondaparinux was favored for orthopedic patients. Fondaparinux was associated with increased bleeding events. Newer agents rivaroxaban and dabigatran may offer additional value. Of all economic evaluations, 64% were supported by manufacturers of a "new" agent. The new agent had a favorable outcome in 38 (97.4%) of 39 evaluations [95% confidence interval [CI] (86.5 to 99.9)]. Among studies supported by a pharmaceutical company, the sponsored medication was economically attractive in 24 (96.0%) of 25 [95% CI, 80.0 to 99.9)]. We could not detect a consistent bias in outcome based on sponsorship; however, only a minority of studies were unsponsored.

Conclusion

Low-molecular-weight heparins and fondaparinux are the most economically attractive drugs for venous thromboembolism prevention in hospitalized patients. Approximately two thirds of evaluations were supported by the manufacturer of the new agent; such drugs were likely to be reported as economically favorable.

Comparison of the effectiveness and safety of low-molecular weight heparin versus unfractionated heparin anticoagulation after heart valve surgery

Although unfractionated heparin (UFH) is used routinely after heart valve surgery at many institutions, cardiovascular surgery patients have a particularly high risk for developing heparin-induced thrombocytopenia (HIT). The aim of this study was to compare the efficacy and safety of low-molecular-weight heparin (LMWH) or UFH after heart valve surgery by conducting a retrospective evaluation of consecutive cardiovascular surgery patients in whom the LMWH dalteparin (n = 100) was used as the postoperative anticoagulant. This group was compared to an earlier group of patients who received UFH (n = 103). The main outcomes included the efficacy of the anticoagulant regimens (determined by the incidence of valve thrombosis, arterial thromboembolic events, and venous thromboembolic events) and the safety (determined by major bleeding, HIT, thrombotic events in HIT-positive cases, and death). Overall, there were for fewer thrombotic events in the LMWH-treated group (4% vs 11%, p = 0.11). There was a higher rate of bleeding events in the UFH-treated group (10% vs 3%, p = 0.08). Six patients in the UFH-treated group developed HIT, 4 of whom had thrombotic events (HIT with thrombosis). In the LMWH-treated group, 3 patients developed HIT, 1 of whom had HIT with thrombosis. In conclusion, in this study, an LMWH regimen after heart valve surgery was effective and safe, with fewer thrombotic, bleeding, HIT, and HIT with thrombosis events.

Thrombocytopenia in medical-surgical critically ill patients: prevalence, incidence, and risk factors

OBJECTIVE

The purpose of this study is to describe the prevalence, to analyze the incidence and independent risk factors for thrombocytopenia, and to examine the impact of thrombocytopenia developing in the intensive care unit (ICU) on patient outcome in a well-defined cohort of critically ill patients in a medical-surgical ICU.

MATERIALS AND METHODS

As part of a prospective cohort study examining the frequency and clinical importance of venous thromboembolism in the ICU, we enrolled consecutive patients older than 18 years expected to be in the ICU for more than 72 hours. Exclusion criteria were an admitting diagnosis of trauma, orthopedic surgery or cardiac surgery, pregnancy, and life support withdrawal. Patients had platelet counts performed as directed by clinical need. We defined thrombocytopenia as a platelet count of less than 150 x 10(9)/L and severe thrombocytopenia as a platelet count of less than 50 x 10(9)/L. Protocol-directed care included routine thromboprophylaxis and twice weekly screening ultrasonography of the legs. Patients were followed to hospital discharge.

RESULTS

Of the 261 enrolled patients, 121 (46%, 95% confidence interval [CI], 40%-53%) had thrombocytopenia (62 on ICU admission and 59 acquired during their ICU stay). Patients who developed a platelet count less than 150 x 10(9)/L during their ICU stay had higher ICU and hospital mortality (P = .03 and .005, respectively), required longer mechanical ventilation (P = .05), and were more likely to receive platelets (P < .001), fresh frozen plasma (P = .005), and red blood cell transfusions (P = .004) than patients who did not develop thrombocytopenia. The only independent risk factors for thrombocytopenia developing during the ICU stay were administration of nonsteroidal anti-inflammatory drugs before ICU admission (hazard ratio, 2.8; 95% CI, 1.3-6.0) and dialysis during the ICU stay (hazard ratio, 3.1; 95% CI, 1.2-7.8). Of the 33 patients who underwent 36 tests for heparin-induced thrombocytopenia, none tested positive.

CONCLUSIONS

We found that about 50% of the patients admitted to the ICU had at least one platelet count of less than 150 x 10(9)/L during their ICU stay. Patients who developed thrombocytopenia were more likely to die, required longer duration of mechanical ventilation, and were more likely to require blood product transfusion. Heparin-induced thrombocytopenia was frequently suspected but did not develop in these critically ill patients.

Prevention of Venous Thromboembolism in High-Risk Patients

The prevention of venous thromboembolism (VTE) in patients recovering from major trauma, spinal cord injury (SCI), or other critical illness is often challenging. These patient groups share a high risk for VTE, they often have at least a temporary high bleeding risk, and there are relatively few thromboprophylaxis trials specific to these populations. A systematic literature review has been conducted to summarize the risks and prevention of VTE in these three groups. It is concluded that routine thromboprophylaxis should be provided to major trauma, SCI and critical care patients based on an individual assessment of their thrombosis and bleeding risks. For patients at high risk for VTE, including those recovering from major trauma and SCI, prophylaxis with a low molecular weight heparin (LMWH) should commence as soon as hemostasis has been demonstrated. For critical care patients at lower thrombosis risk, either LMWH or low-dose heparin is recommended. For those with a very high risk of bleeding, mechanical prophylaxis should be instituted as early as possible and continued until pharmacologic prophylaxis can be initiated. The use of prophylactic inferior vena caval filters is strongly discouraged because their potential benefit has not been shown to outweigh the risks or substantial costs. Implementation of thromboprophylaxis in these patients requires a local commitment to this important patient safety priority as well as a highly functional delivery system, based on the use of pre-printed orders, computer prompts, regular audit and feedback, and ongoing quality improvement efforts.

Deep venous thrombosis: clinically silent in the intensive care unit

PURPOSE

The reliability of clinical signs and the physical examination in the evaluation of deep venous thrombosis (DVT) in the critically ill is unknown. The purpose of this study was to determine the diagnostic properties of clinical examination for signs of DVT in a cohort of medical-surgical intensive care unit (ICU) patients using screening compression ultrasonography as a reference standard.

MATERIALS AND METHODS

We prospectively included patients older than 18 years with an expected length of ICU stay of more than 72 hours. Patients underwent bilateral lower limb screening compression ultrasound twice weekly and structured physical examination twice weekly by 2 independent trained research coordinators blinded to the ultrasonography results. We classified patients according to 2 methods: method 1, a DVT Risk Stratification System of 3 categories and method 2, a DVT Risk Score, both of which use the history and physical examination to stratify patients for their risk of DVT.

RESULTS

We included 239 patients in our study, 32 of whom had DVT based on the results of their compression ultrasound. We excluded 7 patients with DVT on ICU admission and 2 who did not undergo any structured examinations. We matched controls with cases (9:1) based on duration of ICU stay. Cases and controls were then allocated to low, moderate, and high risk strata for DVT. Using method 1, the area under the receiver operating characteristic curve (AUC) was 0.57 (95% CI, 0.33-0.78, P = .01). Using method 2, the AUC was 0.59 (95% CI, 0.42-0.75, P = .02). An AUC of 1.0 indicates an ideal test, and AUC of 0.50 indicates a test with no diagnostic utility.

CONCLUSIONS

The history and physical examination for DVT are not useful in detecting lower limb DVT in the ICU.

Giant cell arteritis and cardiovascular disease in older adults

OBJECTIVE

To explore the association between giant cell arteritis (GCA) and subsequent cardiovascular disease in older adults.

DESIGN

Population based retrospective cohort study.

SETTING

The entire province of Ontario, Canada.

PARTICIPANTS

Patients aged 66 years and older with newly diagnosed GCA (n = 1141), osteoarthritis (n = 172,953), or neither (n = 200,000). Patients with neither were randomly selected from the general population and formed the control group.

MAIN OUTCOME MEASURES

The primary composite outcome was based on a subsequent diagnosis or surgical treatment for coronary artery disease, stroke, peripheral arterial disease, or aneurysm or dissection of the aorta.

RESULTS

The composite end point was more common in seniors with GCA (12.1/1000 person-years) than in patients with osteoarthritis (7.3/1000 person-years) or neither condition (5.3/1000 person-years). The adjusted hazard ratio for cardiovascular disease was 1.6 (95% confidence interval (CI) 1.1 to 2.2) in patients with GCA versus patients with osteoarthritis, and 2.1 (95% CI 1.5 to 3.0) in patients with GCA versus unaffected controls.

CONCLUSIONS

Older adults with GCA appear to be at increased risk for developing cardiovascular disease. Whether an aggressive approach to cardiovascular risk factor modification is particularly beneficial in these patients remains to be determined.

Anticoagulant use in patients with chronic renal impairment

Patients with renal failure have an increased risk of both thrombotic and bleeding complications. A number of antithrombotic drugs undergo renal clearance. Therefore, estimation of renal function is necessary when prescribing these drugs to patients with renal dysfunction. Pharmacokinetic and clinical data in patients with chronic renal impairment are limited for several anticoagulants, and adequate administration information is often absent. Dose adjustment of anticoagulants may be indicated when the creatinine clearance falls below 30 mL/min. Unfractionated heparin, argatroban, and vitamin K antagonists generally do not require dose adjustment with renal dysfunction. However, smaller doses of warfarin may be required to achieve a particular target international normalized ratio. Close monitoring of anticoagulation is recommended when argatroban or high doses of unfractionated heparin are administered in patients with severe chronic renal impairment. Low-molecular weight heparins, danaparoid sodium, hirudins, and bivalirudin all undergo renal clearance. Lower doses and closer anticoagulation monitoring may be advisable when these agents are used in patients with chronic renal failure. We recommend that fondaparinux sodium and ximelagatran (not yet licensed) be avoided in the presence of severe renal impairment and be used with caution in patients with moderate renal dysfunction. While acknowledging the lack of pharmacokinetic data, this review provides specific recommendations for the use of anticoagulants in patients with chronic renal impairment.

Prevention of venous thromboembolism: the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy

This article discusses the prevention of venous thromboembolism (VTE) and is part of the Seventh American College of Chest Physicians Conference on Antithrombotic and Thrombolytic Therapy: Evidence-Based Guidelines. Grade 1 recommendations are strong and indicate that the benefits do, or do not, outweigh risks, burden, and costs. Grade 2 suggests that individual patients' values may lead to different choices (for a full understanding of the grading see Guyatt et al, CHEST 2004; 126:179S-187S). Among the key recommendations in this chapter are the following. We recommend against the use of aspirin alone as thromboprophylaxis for any patient group (Grade 1A). For moderate-risk general surgery patients, we recommend prophylaxis with low-dose unfractionated heparin (LDUH) (5,000 U bid) or low-molecular-weight heparin (LMWH) [< or = 3,400 U once daily] (both Grade 1A). For higher risk general surgery patients, we recommend thromboprophylaxis with LDUH (5,000 U tid) or LMWH (> 3,400 U daily) [both Grade 1A]. For high-risk general surgery patients with multiple risk factors, we recommend combining pharmacologic methods (LDUH three times daily or LMWH, > 3,400 U daily) with the use of graduated compression stockings and/or intermittent pneumatic compression devices (Grade 1C+). We recommend that thromboprophylaxis be used in all patients undergoing major gynecologic surgery (Grade 1A) or major, open urologic procedures, and we recommend prophylaxis with LDUH two times or three times daily (Grade 1A). For patients undergoing elective total hip or knee arthroplasty, we recommend one of the following three anticoagulant agents: LMWH, fondaparinux, or adjusted-dose vitamin K antagonist (VKA) [international normalized ratio (INR) target, 2.5; range, 2.0 to 3.0] (all Grade 1A). For patients undergoing hip fracture surgery (HFS), we recommend the routine use of fondaparinux (Grade 1A), LMWH (Grade 1C+), VKA (target INR, 2.5; range, 2.0 to 3.0) [Grade 2B], or LDUH (Grade 1B). We recommend that patients undergoing hip or knee arthroplasty, or HFS receive thromboprophylaxis for at least 10 days (Grade 1A). We recommend that all trauma patients with at least one risk factor for VTE receive thromboprophylaxis (Grade 1A). In acutely ill medical patients who have been admitted to the hospital with congestive heart failure or severe respiratory disease, or who are confined to bed and have one or more additional risk factors, we recommend prophylaxis with LDUH (Grade 1A) or LMWH (Grade 1A). We recommend, on admission to the intensive care unit, all patients be assessed for their risk of VTE. Accordingly, most patients should receive thromboprophylaxis (Grade 1A).

Underlying chronic granulomatous disease in a patient with bronchocentric granulomatosis

We present a case of bronchocentric granulomatosis in a woman with no history of asthma who was colonised with Aspergillusfumigatus. A family history of chronic granulomatous disease prompted further testing that demonstrated severely depressed neutrophil oxidant production and gp91(phox) deficiency compatible with the X linked carrier state of chronic granulomatous disease. Only one report of the association of these two rare diseases has previously appeared in the literature. We postulate that an ineffective immune response led to the prolonged colonisation of Afumigatus resulting in a hypersensitivity reaction that was manifest clinically as bronchocentric granulomatosis.

Deep vein thrombosis and its prevention in critically ill adults

BACKGROUND

Our objective was to systematically review the incidence of deep vein thrombosis (DVT) and the efficacy of thromboprophylaxis in critically ill adults, including patients admitted to intensive care units and following trauma, neurosurgery, or spinal cord injury.

METHODS

Two authors independently searched MEDLINE, EMBASE, abstract databases, and the Cochrane database. Data were extracted independently in triplicate.

RESULTS

Ten percent to 30% of medical and surgical intensive care unit patients develop DVT within the first week of intensive care unit admission. The use of subcutaneous low-dose heparin reduced the rate by 50% compared with no prophylaxis. Approximately 60% of trauma patients developed DVT within the first 2 weeks of admission. Use of unfractionated heparin appears to decrease the incidence of DVT by only 20%, whereas low-molecular-weight heparin decreases the incidence by a further 30%. The estimated prevalence of DVT in neurosurgical patients not given prophylaxis is 22% to 35%. Mechanical prophylaxis is efficacious, with a pooled odds ratio in 5 randomized trials of 0.28. Use of low-molecular-weight heparin has been investigated as an adjunct to mechanical prophylaxis with a pooled odds ratio of 0.59 compared with graduated compression stockings alone. The incidence of DVT without prophylaxis in acute spinal cord injury patients is likely in excess of 50% to 80%. Studies of prophylaxis in these patients are too sparse to come to any definitive conclusion.

CONCLUSIONS

Critically ill patients commonly develop DVT, with rates that vary from 22% to almost 80%, depending on patient characteristics. Methods of prophylaxis proven in one group do not necessarily generalize to other critically ill patient groups. More potent prophylactic regimens other than unfractionated or low-molecular-weight heparins alone may be needed with higher-risk groups.

Subcutaneous heparin versus low-molecular-weight heparin as thromboprophylaxis in patients undergoing colorectal surgery: results of the canadian colorectal DVT prophylaxis trial: a randomized, double-blind trial

OBJECTIVE

To compare the effectiveness and safety of low-dose unfractionated heparin and a low-molecular-weight heparin as prophylaxis against venous thromboembolism after colorectal surgery.

METHODS

In a multicenter, double-blind trial, patients undergoing resection of part or all of the colon or rectum were randomized to receive, by subcutaneous injection, either calcium heparin 5,000 units every 8 hours or enoxaparin 40 mg once daily (plus two additional saline injections). Deep vein thrombosis was assessed by routine bilateral contrast venography performed between postoperative day 5 and 9, or earlier if clinically suspected.

RESULTS

Nine hundred thirty-six randomized patients completed the protocol and had an adequate outcome assessment. The venous thromboembolism rates were the same in both groups. There were no deaths from pulmonary embolism or bleeding complications. Although the proportion of all bleeding events in the enoxaparin group was significantly greater than in the low-dose heparin group, the rates of major bleeding and reoperation for bleeding were not significantly different.

CONCLUSIONS

Both heparin 5,000 units subcutaneously every 8 hours and enoxaparin 40 mg subcutaneously once daily provide highly effective and safe prophylaxis for patients undergoing colorectal surgery. However, given the current differences in cost, prophylaxis with low-dose heparin remains the preferred method at present.

The risk of venous thromboembolism is increased throughout the course of malignant glioma: an evidence-based review

BACKGROUND

Venous thromboembolism (VTE) frequently complicates the course of patients with cancer, and there is evidence to suggest that patients with brain tumors are at particularly high risk. The objective of this methodology-based literature review was to quantify the rate of incidence of VTE in patients with malignant glioma and to determine the factors that predict an increased risk of this complication.

METHODS

Studies meeting predefined inclusion criteria were evaluated independently on an eight-item methodology index by three raters. Authors were contacted to resolve ambiguities. The results of the studies were summarized and the incidence rate of VTE within the early postoperative phase and during extended follow-up were reported separately.

RESULTS

Within 6 weeks after surgery the incidence rate of deep venous thrombosis (DVT) ranged from 3% to 60%, varying with the prophylaxis regimen used, the method of diagnosis, and the study design. Beyond 6 weeks postoperatively, the rates of DVT ranged from 0.013 to 0.023 per patient-month of follow-up. The single study with no significant methodologic deficiencies found a 24% rate of incidence of symptomatic DVT over the 17 months of follow-up beyond the first 6 postoperative weeks. In 6 studies the presence of leg paresis, histologic diagnosis of glioblastoma multiform, age >/= 60 years, large tumor size, use of chemotherapy, and length of surgery > 4 hours were identified as possible risk factors.

CONCLUSIONS

The incidence of VTE is high throughout the course of malignant glioma. A randomized, controlled trial is needed to clarify whether the benefits of long term anticoagulant prophylaxis outweigh the risks and costs of such therapy.

Allogeneic red blood cell transfusion is an independent risk factor for the development of postoperative bacterial infection

BACKGROUND AND OBJECTIVES

Allogeneic red blood cell transfusions may exert immunomodulatory effects in recipients including an increased rate of postoperative bacterial infection. It is controversial whether allogeneic transfusion is an independent predictor for the development of postoperative bacterial infection.

METHODS

We analysed a prospectively collected database of 1,349 patients undergoing colorectal surgery in 11 centres across Canada. The primary outcome was the development of either a postoperative wound infection or intra-abdominal sepsis in transfused and nontransfused patients. The effect of allogeneic transfusion on postoperative infection was evaluated with adjustment for all the confounding factors in a multiple regression analysis.

RESULTS

The 282 patients who received a total of 832 allogeneic units had a significantly higher frequency of wound infections and intra-abdominal sepsis than the patients who were not transfused (25. 9 vs. 14.2%, p = 0.001). A significant dose-response relationship between transfusion and infection rate was demonstrated. Multiple regression analysis identified allogeneic transfusion as a statistically significant independent predictor for postoperative bacterial infection (OR 1.18, 95% CI 1.05-1.33, p = 0.007). Other independent predictors were anastomotic leak, repeat operation, patient age and preoperative haemoglobin level. The mortality rate was also significantly higher in the transfused group.

CONCLUSION

These data support the hypothesis that allogeneic red cell transfusion is an independent risk factor for the development of postoperative bacterial infection in patients undergoing colorectal surgery. This association provides further reason to minimise exposure to allogeneic transfusions in the perioperative setting.

The management of asthma: a case-scenario-based survey of family physicians and pulmonary specialists

This study assessed family physicians' and pulmonary specialists' approaches to the treatment of adult outpatient asthma using a self-administered questionnaire consisting of six asthma scenarios of varying severity levels. One hundred sixty-three randomly selected family physicians and pulmonary specialists completed the questionnaire (response rate of 80%). We observed that, regardless of asthma severity, more than 75% of physicians (regardless of specialty) would not include oral theophylline or nonsteroidal anti-inflammatory preparations in their treatment approach. Pulmonary specialists' and family physicians' approaches to mild asthma were similar (more than 90% recommended an inhaled beta2-agonist). However, considerable differences existed among and between physician groups for the remaining scenarios. For example, with an exacerbation associated with an upper respiratory tract infection, family physicians were more likely to recommend oral antibiotics (p<0.0001) and a same-day outpatient visit (p<0.0001), whereas specialists were more likely to increase the inhaled corticosteroid dosage (p<0.0001). Overall, disagreement was observed almost twice as often among family physicians than among specialists. Our results suggest that physicians vary markedly in their reported use of most interventions available to treat asthma, even when the disease severity is specified.

Venous Thromboembolism: Risk Factors and Prophylaxis

Venous thromboembolism is a common disease in the community and the most frequent preventable cause of hospital death. Acquired and inherited risk factors for thrombosis have been extensively studied over the past two decades. These factors and the clinical setting allow the stratification of most hospitalized patients into low-, moderate-, and high-risk groups. For patients in the moderate- and high-risk categories, routine thromboprophylaxis can decrease the morbidity and mortality from thromboembolic complications as well as reduce patient care expenditures. Low-dose heparin is generally the most appropriate prophylaxis for moderate-risk patients, and either low molecular weight heparin or adjusted-dose warfarin is generally the most appropriate for high-risk patients.

Physicians' approaches to providing asthma education to patients and the level of patient involvement in management decisions

The objectives of this study were to describe physicians' self-reported approaches to providing disease-specific education to adults with asthma in an outpatient setting and their opinions about the level of patient involvement in management decisions. A mailed questionnaire was completed by 163 randomly selected physicians, representing an 80% response rate. The educational actions provided most frequently included information about prescribed medications (90%-100% of physicians), general asthma information (87%-98%), and inhaler demonstration (85%-95%). Educational activities provided least frequently were action plans (7%-74%) and referral to a nonprofit community asthma organization for further information (18%-36%). The reported provision of asthma education was related to patients' asthma severity (p < 0.0001) and physician specialty (p < 0.005). Physicians indicated that their patients were less involved in asthma management decisions than they would prefer (p < 0.001). The results suggest that physicians vary markedly in their approaches to providing asthma education to patients. Future descriptive and intervention studies are needed to identify the most effective models for providing education and patient involvement.

The incidence of symptomatic venous thromboembolism during and after prophylaxis with enoxaparin: a multi-institutional cohort study of patients who underwent hip or knee arthroplasty. Canadian Collaborative Group

BACKGROUND

Despite low molecular weight heparin prophylaxis, the incidence of venographically detected, residual deep vein thrombosis after hip and knee arthroplasty remains high, at approximately 15% and 30%, respectively. Most of these thrombi are asymptomatic and of unknown clinical significance. Nevertheless, because they have the potential to grow, limiting prophylaxis to the in-hospital period may provide inadequate protection.

METHODS

We studied a cohort of 1984 consecutive patients who had hip or knee arthroplasty at 1 of 28 participating hospitals. Patients received enoxaparin prophylaxis, 30 mg subcutaneously every 12 hours for up to 14 days, and underwent predischarge compression ultrasonography. Study end points were symptomatic deep vein thrombosis or pulmonary embolism during and after prophylaxis, asymptomatic venous thrombosis detected by predischarge compression ultrasonography, and major hemorrhage. The duration of follow-up was 84 days.

RESULTS

Enoxaparin treatment was started a mean (+/- SD) of 17.9 +/- 10.4 hours after the completion of surgery and was given for a mean of 18.0 +/- 6.9 doses. Eighty-two patients (4.1%; 95% confidence interval, 3.3%-5.0%) developed venous thromboembolism. The rates of thromboembolic events during and after prophylaxis were 2.1% and 2.0%, respectively. Only 3 patients (0.15%) had abnormal predischarge compression ultrasonography. Three patients (0.15%) died of pulmonary embolism. Major hemorrhage occurred in 58 patients (2.9%; 95% confidence interval, 2.2%-3.7%).

CONCLUSIONS

Postoperative prophylaxis with enoxaparin for a mean of 9 days is associated with a clinically acceptable rate of symptomatic venous thromboembolism and major hemorrhage. Predischarge compression ultrasonography cannot be justified.

Practical management of venous thromboembolism following pelvic fractures

The management of thromboembolic complications remains one of the most controversial issues in the care of patients with pelvic and acetabular fractures. Recent studies have indicated that the incidence of proximal deep vein thrombosis is much higher than was previously believed. These patients should be managed with a formal institutional protocol that includes universal prophylaxis, supplemented in some cases by screening for deep vein thrombosis.

A comparison of low-dose heparin with low-molecular-weight heparin as prophylaxis against venous thromboembolism after major trauma

BACKGROUND

Patients who have had major trauma are at very high risk for venous thromboembolism if they do not receive thromboprophylaxis. We compared low-dose heparin and a low-molecular-weight heparin with regard to efficacy and safety in a randomized clinical trial in patients with trauma.

METHODS

Consecutive adult patients admitted to a trauma center who had Injury Severity Scores of at least 9 and no intracranial bleeding were randomly assigned to heparin (5000 units) or enoxaprin (30 mg), each given subcutaneously every 12 hours in a double-blind manner, beginning within 36 hours after the injury. The primary outcome was deep-vein thrombosis as assessed by contrast venography performed on or before day 14 after randomization.

RESULTS

Among 344 randomized patients, 136 who received low-dose heparin and 129 who received enoxaparin had venograms adequate for analysis. Sixty patients given heparin (44 percent) and 40 patients given enoxaparin (31 percent) had deep-vein thrombosis (P=0.014). The rates of proximal-vein thrombosis were 15 percent and 6 percent, respectively (P=0.012). The reductions in risk with enoxaparin as compared with heparin were 30 percent (95 percent confidence interval, 4 to 50 percent) for all deep-vein thrombosis and 58 percent (95 percent confidence interval, 12 to 87 percent) for proximal-vein thrombosis. Only six patients (1.7 percent) had major bleeding (one in the heparin group and five in the enoxaparin group, P=0.12).

CONCLUSIONS

Low-molecular-weight heparin was more effective than low-dose heparin in preventing venous thromboembolism after major trauma. Both interventions were safe.

Evaluation of an intravenous heparin nomogram in a coronary care unit

OBJECTIVE

To develop, implement and evaluate an effective and efficient heparin nomogram.

DESIGN

Retrospective and prospective data collection.

SETTING

Coronary care unit (CCU) of a university-affiliated hospital.

PATIENTS

Patients with acute coronary ischemic syndromes requiring intravenous (i.v.) heparin who were not receiving thrombolytic and/or warfarin therapy.

INTERVENTIONS

A retrospective chart review of 52 CCU patients receiving iv heparin provided the historical control group. The effectiveness of a heparin nomogram (5000 U bolus followed by an initial weight-based infusion of 15 U/kg/h with subsequent rate adjustments according to activated partial thromboplastin time [aPTT] results) was then prospectively assessed in a further 56 consecutive patients.

MAIN RESULTS

The historical control and nomogram groups did not significantly differ with respect to age, weight, duration of therapy or total number of aPTTs drawn. Approximately 79% and 84% of patients in the control and nomogram groups, respectively, achieved an aPTT within the therapeutic range (60 to 90 s, P > 0.05), whereas 89% and 100% of control and nomogram patients, respectively, surpassed the therapeutic threshold (longer than 60 s) at some point during treatment (P = 0.009). Compared with empiric dose adjustment, the nomogram more effectively avoided periods of inadequate anticoagulation. Similarly, the time to achieve the therapeutic threshold was significantly longer in the control than in the nomogram group (8.2 +/- 5.9 versus 6.7 +/- 3.7 h, P = 0.026). No adverse bleeding events were noted in either group.

CONCLUSIONS

Compared with conventional approaches, the heparin nomogram successfully achieved and maintained adequate anticoagulation in a greater proportion of patients with acute cardiovascular diseases without the need for additional aPTT measurements.

Thromboembolic complications in patients with pelvic trauma

Patients with pelvic trauma are known to be at increased risk for the development of thromboembolic complications. The incidence of deep venous thrombosis in patients with pelvic fractures is 35% to 60%. Proximal deep venous thrombosis, which is most likely to result in pulmonary embolism, occurs in 25% to 35% of these patients, and almost 1/2 of all proximal thrombi will be in the pelvic veins. The incidence of symptomatic pulmonary embolism in the pelvic trauma population is 2% to 10% whereas a greater proportion of patients will have clinically silent pulmonary embolism. Fatal pulmonary embolism occurs in 0.5% to 2% of patients with pelvic trauma. The cornerstone of effective management is prophylaxis and the most commonly used forms include low dose heparin, low molecular weight heparin, mechanical devices, and in some studies, inferior vena caval filters. Based on a critical review of the literature, in algorithm is proposed for the management of thromboprophylaxis in this trauma subgroup. This includes prophylaxis, screening, and treatment when proximal thrombosis is identified. Such a systematic approach to this potentially catastrophic problem may decrease the morbidity and mortality associated with thromboembolic complications in these patients.

Prevention of venous thromboembolism after knee arthroplasty. A randomized, double-blind trial comparing enoxaparin with warfarin

OBJECTIVE

To compare the effectiveness and safety of fixed-dose enoxaparin and adjusted dose warfarin in preventing venous thromboembolism after knee arthroplasty.

DESIGN

A randomized, double-blind controlled trial.

SETTING

8 university hospitals.

PATIENTS

670 consecutive patients who had knee arthroplasty.

INTERVENTION

Patients were randomly assigned to receive enoxaparin (30 mg subcutaneously every 12 hours) or adjusted-dose warfarin (international normalized ratio, 2.0 to 3.0). Both regimens were started after surgery.

MEASUREMENTS

The primary end point was the incidence of deep venous thrombosis in patients with adequate bilateral venograms; the secondary end point was hemorrhage.

RESULTS

Among the 417 patients with adequate venograms, 109 of 211 warfarin recipients (51.7%) had deep venous thrombosis compared with 76 of 206 enoxaparin recipients (36.9%) (P = 0.003). The absolute risk difference was 14.8% in favor of enoxaparin (95% Cl, 5.3% to 24.1%) Twenty-two warfarin recipients (10.4%) and 24 enoxaparin recipients (11.7%) had proximal venous thrombosis (P>0.2). The absolute risk difference was 1.2% in favor of warfarin (Cl, -7.2% to 4.8%). The incidence of major bleeding was 1.8% (6 of 334 patients) in the warfarin group and 2.1% (7 of 336 patients) in the enoxaparin group (P>0.2). The absolute risk difference was 0.3% in favor of warfarin (Cl, -2.4% to 1.8%).

CONCLUSIONS

A postoperative, fixed-dose enoxaparin regimen is more effective than adjusted-dose warfarin in preventing deep venous thrombosis after knee arthroplasty. No differences were seen in the incidence of proximal venous thrombosis or clinically overt hemorrhage.

Low-molecular-weight heparinoid orgaran is more effective than aspirin in the prevention of venous thromboembolism after surgery for hip fracture

BACKGROUND

The study objective was to determine the relative efficacy and safety of a low-molecular-weight heparinoid (Orgaran) compared with aspirin for the prevention of postoperative venous thromboembolism in patients undergoing surgery for fractured hips. A double-blind, randomized, controlled trial was used to study 251 consecutive eligible and consenting patients undergoing surgery for hip fracture in seven participating hospitals.

METHODS AND RESULTS

Patients received either fixed-dose Orgaran by subcutaneous injection every 12 hours in a dose of 750 anti-Factor Xa units or aspirin 100 mg orally twice daily; both regimens were started 12 to 24 hours after surgery and continued for 14 days or until discharge, if sooner. All patients had postoperative 125I-fibrinogen leg scanning and impedance plethysmography. If the results of one or both tests were positive, then venography was performed. Otherwise, venography was done at day 14, or sooner if the patient was ready for discharge. Pulmonary embolism in symptomatic patients was diagnosed on the basis of a high probability perfusion/ventilation lung scan, a positive angiogram, or a clinically significant embolism detected at autopsy. Evaluable venograms were obtained in 90 of the 125 patients randomly assigned to receive Orgaran and in 87 of the 126 patients assigned to receive aspirin. Venous thromboembolism was detected in 25 (27.8%) patients in the Orgaran group and in 39 (44.3%) patients in the aspirin group. Thus, there was a relative risk reduction of 37% with Orgaran (P=.028; 95% confidence interval, 3.7% to 59.7%). Six (6.8%) of 88 patients in the Orgaran group and 12 (14.3%) of 84 patients in the aspirin group developed proximal deep vein thrombosis or pulmonary embolism, a relative risk reduction of 52% with Orgaran (P=.137; 95% confidence interval, -30.7% to 84.6%). Hemorrhagic complications occurred in 2 (1.6%) patients given Orgaran and 8 (6.4%) patients given aspirin (P=.10). There was one major bleed in the Orgaran group compared with four in the aspirin group.

CONCLUSIONS

This study demonstrates that Orgaran is significantly more efficacious than aspirin in preventing postoperative venous thromboembolism in patients undergoing surgery for fractured hips, with no evidence of any increase in hemorrhagic complications.

Nontapering versus tapering prednisone in acute exacerbations of asthma: a pilot trial

Controversy exists as to whether or not the dose of prednisone should be tapered in patients discharged from the emergency department after initial treatment for an acute exacerbation of asthma. We assessed the rates of relapse and rebound in a group of 28 patients treated with a nontapering course of prednisone and compared their outcomes to an historical control group of 48 patients treated with a typical tapering course of prednisone. We found no significant difference in the rates of relapse or rebound between the nontapering dose patients and the tapering dose patients within either 21 days of discharge or within 10 days after stopping prednisone. Fifty-four percent of study patients reported adverse effects that could be attributed to prednisone. Our preliminary findings suggest that tapering of prednisone may not be needed in these patients.

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.

Prevention of deep vein thrombosis after major knee surgery--a randomized, double-blind trial comparing a low molecular weight heparin fragment (enoxaparin) to placebo

Consecutive patients undergoing knee arthroplasty or tibial osteotomy at four participating hospitals received either enoxaparin, 30 mg subcutaneously every 12 h (n = 66) or an identical-appearing placebo (n = 65). All study medications started the morning after the operation and were continued up to a maximum of 14 days. Patients underwent surveillance with 125I-fibrinogen leg scanning and impedance plethysmography. Bilateral contrast venography was performed routinely at Day 14 or at time of discharge, if sooner. Deep vein thrombosis was detected by venography in 35 of 54 patients (65%) in the placebo group and in 8 of 41 patients in the enoxaparin group (19%), a risk reduction of 71%, P less than 0.0001. For the entire study group, deep vein thrombosis was detected by either venography of non-invasive tests in 37 of 64 patients (58%) in the placebo group and in 11 of 65 patients (17%) in the enoxaparin group, a risk reduction of 71%, P less than 0.0001. Proximal vein thrombosis was found in 19% of the placebo patients and in none of the enoxaparin patients, a risk reduction of 100%, P less than 0.001. Bleeding complications occurred in 5 of 65 patients (8%) in the placebo group and in 4 of 66 patients (6%) in the enoxaparin group, P = 0.71. There were no differences in the amount of blood loss, minimum hemoglobin levels and number of units of packed red cells given between the two treatment groups. We conclude that a fixed dose regimen of enoxaparin, started post-operatively, is an effective and safe regimen for reducing the frequency of deep vein thrombosis after major knee surgery.

Continuous intravenous heparin compared with intermittent subcutaneous heparin in the initial treatment of proximal-vein thrombosis

We performed a randomized double-blind trial comparing continuous intravenous heparin with intermittent subcutaneous heparin in the initial treatment of 115 patients with acute proximal deep-vein thrombosis. Intermittent subcutaneous heparin as administered in this trial was inferior to continuous intravenous heparin in preventing recurrent venous thromboembolism. The subcutaneous heparin regimen induced an initial anticoagulant response below the target therapeutic range in the majority of patients and resulted in a high frequency of recurrent venous thromboembolism (11 of 57 patients, 19.3 percent), which was virtually confined to patients with a subtherapeutic anticoagulant response. In contrast, continuous intravenous heparin induced a therapeutic anticoagulant response in the majority of patients and a low frequency of recurrent events (3 of 58 patients, 5.2 percent; P = 0.024); the recurrences were limited to patients with an initial subtherapeutic anticoagulant response. The results of this trial establish the efficacy of intravenous heparin in the treatment of proximal venous thrombosis and suggest a relation between the effectiveness of heparin and the levels of anticoagulation achieved; such a relation could explain the observed failure of the subcutaneous regimen.