Perioperative Venous Thromboembolism Prophylaxis

Venous thromboembolism (VTE) is a preventable cause of postoperative morbidity and mortality; however, audits suggest that the use of thromboprophylaxis is underused. In this review, we describe our approach to prevention of postoperative VTE and provide guidance on how to formulate an optimal VTE prophylaxis plan. We recommend that all patients undergo thrombosis- and bleeding-risk assessment as part of their preoperative evaluation. The risk of thrombosis can be estimated based on patient- and procedure-specific factors, using validated risk-assessment models such as the Caprini score. There are no validated models to predict perioperative bleeding; however, several risk factors have been proposed. Patients should ambulate early and frequently after surgery. We recommend no additional prophylaxis in patients at very low risk of VTE (Caprini score 0). Patients at low risk of VTE (Caprini 1 to 2) are recommended to receive either mechanical or pharmacological prophylaxis. Patients at moderate (Caprini 3 to 4) to high risk of VTE (Caprini ≥5) are recommended pharmacological prophylaxis either alone or combined with mechanical prophylaxis. Patients at high risk of bleeding should receive mechanical prophylaxis until their risk of bleeding is reduced and pharmacological prophylaxis can be reconsidered. Populations for which the Caprini score has not been validated (such as orthopedic surgery) are recommended prophylaxis based on individual and procedure-specific risk factors. Prophylaxis is typically continued until the patient is ambulatory or until hospital dismissal; however, longer durations can be considered in certain circumstances (high-risk patients undergoing malignant abdominopelvic operations, bariatric operations, and certain orthopedic operations).

Characteristics and quality of rotation-specific resident learning goals: a prospective study

Background: Residents are expected to develop the skills to set learning goals. Setting learning goals is part of self-regulated learning, setting the foundation for creating a learning plan, deploying learning strategies, and assessing their progress to those goals. While effective goal setting is essential to resident self-regulated learning, residents struggle with setting learning goals and desire faculty assistance with goal setting.Objective: We aimed to characterize the topics and quality of residents' rotation-specific learning goals.Design: We conducted a prospective study of 153 internal medicine residents, assessing 455 learning goals for general medicine inpatient rotations. We coded learning goal themes, competencies, and learning domains, and assessed quality using the validated Learning Goal Scoring Rubric. We compared topic categories, competencies, learning domains, and quality between the first and second months of postgraduate (PGY)-1 residents and between PGY-1 and PGY-3 residents. We assessed factors associated with learning goal completion.Results: The overall response rate was 80%. The top three learning goal categories were patient management, specific diseases related to general medicine, and teaching skills. There were no changes in learning goal characteristics between PGY-1 months (p ≥ 0.04). There were differences between PGY-1 and PGY-3 residents' learning goals in patient management (28% vs 6%; p < .001), specific disease conditions (19% vs 3%; p < .001), and teaching skills (2% vs 56%; p < .001). There was no difference in learning goal quality between PGY-1 months (1.63 vs. 1.67; p = 0.82). The PGY-3 learning goals were of higher quality than PGY-1 learning goals for the 'specific goal' item (1.38 vs. 0.98, p = 0.005), but not for other items or overall (all p ≥ 0.02). Residents reported 85% (297/347) learning goal completion.Conclusions: Resident rotation-specific learning goals reflect a broad array of topics. Residents' learning goal quality was low and residents may benefit from guidance to support residents' learning goals.

Unfractionated heparin infusion for treatment of venous thromboembolism based on actual body weight without dose capping

Controversy exists regarding the use of dose capping of weight-based unfractionated heparin (UFH) infusions in obese and morbidly obese patients. The primary objective of this study was to compare time to first therapeutic activated partial thromboplastin time (aPTT) in hospitalized patients receiving UFH for acute venous thromboembolism (VTE) among three body mass index (BMI) cohorts: non-obese (< 30 kg/m2), obese (30–39.9 kg/m2), and morbidly obese (⩾ 40 kg/m2). In this single-center, retrospective cohort study, patients were included if they ⩾ 18 years of age, had a documented VTE, and were on an infusion of UFH for at least 24 hours. Weight-based UFH doses were calculated using actual body weight. A total of 423 patients met the inclusion criteria, with 230 (54.4%), 146 (34.5%), and 47 (11.1%) patients in the non-obese, obese, and morbidly obese cohorts, respectively. Median times to therapeutic aPTT were 16.4, 16.6, and 17.1 hours in each cohort. Within 24 hours, the cumulative incidence rates for therapeutic aPTT were 70.7% for the non-obese group, 69.9% for the obese group, and 61.7% for the morbidly obese group (obese vs non-obese: HR = 1.02, 95% CI: 0.82–1.26, p = 0.88; morbidly obese vs non-obese: HR = 0.87, 95% CI: 0.62–1.21, p = 0.41). There was no significant difference in major bleeding events between BMI groups (obese vs non-obese, p = 0.91; morbidly obese vs non-obese, p = 0.98). Based on our study, heparin dosing based on actual body weight without a dose cap is safe and effective.

Apixaban and Rivaroxaban in Patients With Acute Venous Thromboembolism

OBJECTIVE

To compare the clinical efficacy and safety of apixaban with those of rivaroxaban for the treatment of acute venous thromboembolism (VTE).

PATIENTS AND METHODS

Consecutive patients enrolled in the Mayo Thrombophilia Clinic Registry (between March 1, 2013, and January 30, 2018) and treated with apixaban or rivaroxaban for acute VTE were followed forward in time. The primary efficacy outcome was VTE recurrence. The primary safety outcome was major bleeding; the second safety outcome was clinically relevant nonmajor bleeding (CRNMB); and the third was a composite of major bleeding or CRNMB.

RESULTS

Within the group of 1696 patients with VTE enrolled, 600 (38%) were treated either with apixaban (n=302, 50%) or rivaroxaban (n=298, 50%) within the first 14 days of VTE diagnosis and who completed at least 3 months of therapy or had a study event. Recurrent VTE was diagnosed in 7 patients (2.3%) treated with apixaban and in 6 (2%) treated with rivaroxaban (adjusted hazard ratio [aHR], 1.4; 95% CI, 0.5-3.8). Major bleeding occurred in 11 patients (3.6%) receiving apixaban and in 9 patients (3.0%) receiving rivaroxaban (aHR, 1.2; 95% CI, 0.5-3.2). Clinically relevant nonmajor bleeding was diagnosed in 7 patients (2.3%) receiving apixaban and in 20 (6.7%) receiving rivaroxaban (aHR, 0.4; 95% CI, 0.2-0.9). The rates of composite major bleeding or CRNMB were similar (aHR, 0.6; 95% CI, 0.3-1.2). Most study events occurred in patients with cancer.

CONCLUSION

In the setting of a standardized, guideline-directed, patient-oriented clinical practice, the efficacy and safety of apixaban and rivaroxaban for the treatment of acute VTE were comparable.

Updates in venous thromboembolism management: evidence published in 2017

Venous thromboembolism (VTE) management is rapidly evolving and staying up-to-date is challenging. We identified the most practice-informing articles published in 2017 relevant to the nonspecialist provider managing VTE. We performed a systematic search of the literature (Appendix A), limiting the search to a publication date of 2017. Two reviewers screened the 2735 resulting abstracts to identify high-quality, clinically relevant publications related to VTE management. One-hundred and six full-text articles were considered for inclusion. The five authors used a modified Delphi method to reach consensus on inclusion of seven articles for in-depth appraisal, following predetermined criteria of clinical relevance to nonspecialist providers, potential for practice change, and strength of the evidence.

Improving inpatient warfarin therapy safety using a pharmacist-managed protocol

Introduction

Safe management of warfarin in the inpatient setting can be challenging. At the Mayo Clinic hospitals in Rochester, Minnesota, we set out to improve the safety of warfarin management among surgical and non-surgical inpatients.

Methods

A multidisciplinary team designed a pharmacist-managed warfarin protocol (PMWP) which designated warfarin dosing to inpatient pharmacists with guidance from computerised dosing algorithms. Ordering this protocol was ultimately designed as an ‘opt out’ practice. The primary improvement measure was frequency of international normalised ratio (INR) greater than 5; secondary measures included adoption rate of the protocol, a counterbalance INR metric (INR <1.7 three days after first inpatient warfarin dose), and complication rates, including bleeding and thrombosis events. An interrupted time series analysis was conducted to compare outcomes.

Results

Among over 50 000 inpatient warfarin recipients, the PMWP was adopted for the majority of both surgical and non-surgical inpatients during the study period (1 January 2005 to 31 December 2011). The primary improvement measure decreased from 5.6% to 3.4% for medical patients and from 5.2% to 2.4% for surgical patients during the preimplementation and postimplementation periods, respectively. The INR counterbalance measure did not change. Postoperative bleeding decreased from 13.5% to 11.1% among surgical patients, but bleeding was unchanged among medical patients.

Conclusion

Our PMWP led to achievement of improved INR control for inpatient warfarin recipients and to less near-term bleeding among higher risk, surgical patients.

Testicular vein thrombosis: Incidence of recurrent venous thromboembolism and survival

PURPOSE

Testicular vein thrombosis (TVT) etiology, recurrence, and survival were compared with lower extremity deep vein thrombosis (DVT) in order to determine whether treatment guidelines for DVT could be applied to TVT.

PATIENTS AND METHODS

An inception cohort of patients with confirmed TVT (January 1995-October 2015) was compared to a control group of patients with lower extremity DVT matched by age, gender, and diagnosis date.

RESULTS

Thirty-nine men with TVT were identified; 15 (38%) with isolated TVT. Left testicular vein was affected in 77% patients; there were no cases of bilateral TVT. Cancer was over twofold more common in TVT patients (59% vs 28%, P = .01). Most cancers (78%) involved organs in proximity to the testicular vein. Although TVT patients were less frequently treated with anticoagulants (49% vs 97%, P = .0001), recurrence rates were similar to DVT group (TVT 4.2 vs DVT 1.1 per 100 patient-years, P = .11). Despite higher cancer prevalence, survival rates were similar between groups (31% vs 28%; P = .34). Major bleeding events were rare (one patient per group).

CONCLUSIONS

Identifying TVT should prompt a search for a regional malignancy. Despite the high cancer prevalence and low utilization of anticoagulants, recurrent venous thrombosis and mortality rates are similar to DVT patients.

Updates in venous thromboembolism management: evidence published in 2016

The management of venous thromboembolic disease (VTE) is rapidly evolving and staying updated on practice-changing evidence can be challenging. In an attempt to alleviate this daunting task, we sought to determine the most important practice-informing articles published in 2016 relevant to the non-specialist provider managing VTE. We performed a systematic search of the literature, limiting the search to a publication date of 2016 (see Supplementary Appendix). Two reviewers screened the 3819 resulting abstracts to identify high-quality, clinically relevant publications related to VTE management. Two hundred sixteen full-text articles were considered for inclusion. The five authors used a modified Delphi method to reach consensus on inclusion of 7 articles for in-depth appraisal, following predetermined criteria of clinical relevance to non-specialist providers, potential for practice change, and strength of the evidence.

Going Beyond Administrative Data: Retrospective Evaluation of an Algorithm Using the Electronic Health Record to Help Identify Bleeding Events Among Hospitalized Medical Patients on Warfarin

To reliably assess quality, a standardized electronic approach is needed to identify bleeding events. The study aims were the following: (1) clinically validate an electronic health record–based algorithm for bleeding and (2) assess interrater results to determine validity and reliability. Data were analyzed before and after implementation of a pharmacist-managed warfarin protocol. Bleeding was based on ≥2 of 3 criteria: (1) diagnosis indicating bleeding, (2) lab value decrease suggesting bleeding, and (3) blood product use. All suspected bleeds (234) and a sample (58) not meeting criteria were compared with clinical review. There were 234 bleeding cases identified electronically. Reviewer agreement was 78.2% (κ = 0.565). Algorithm sensitivity was 93.9% and positive predictive value 46.2%. Algorithm identification was least accurate for those with only 2 criteria but good for those with all criteria. This study supports using multiple electronic criteria to identify bleeding events. However, cases having exactly 2 criteria may require manual review for validation.

Update in perioperative medicine: practice-changing evidence published in 2015

Evidence in perioperative medicine is published in a wide variety of journals, given the multidisciplinary nature of its practice which spans medicine and its subspecialties, as well as surgery and anesthesiology. It can be difficult to identify new and important evidence, as perioperative practice continues to evolve in multiple areas such as medication management, anticoagulation and cardiac risk stratification, among others. New, high-quality evidence is published each year, and must be placed into the context of not only existing literature, but also practical real-world patient care. We sought to systematically identify, critically evaluate and concisely summarize the practice implications of 10 articles published in 2015 for the practicing perioperative clinician.

Prevention of venous thromboembolism in patients undergoing bariatric surgery

Bariatric surgical procedures are now a common method of obesity treatment with established effectiveness. Venous thromboembolism (VTE) events, which include deep vein thrombosis and pulmonary embolism, are an important source of postoperative morbidity and mortality among bariatric surgery patients. Due to an understanding of the frequency and seriousness of these complications, bariatric surgery patients typically receive some method of VTE prophylaxis with lower extremity compression, pharmacologic prophylaxis, or both. However, the optimal approach in these patients is unclear, with multiple open questions. In particular, strategies of adjusted-dose heparins, postdischarge anticoagulant prophylaxis, and the role of vena cava filters have been evaluated, but only to a limited extent. In contrast to other types of operations, the literature regarding VTE prophylaxis in bariatric surgery is notable for a dearth of prospective, randomized clinical trials, and current professional guidelines reflect the uncertainties in this literature. Herein, we summarize the available evidence after systematic review of the literature regarding approaches to VTE prevention in bariatric surgery. Identification of risk factors for VTE in the bariatric surgery population, analysis of the effectiveness of methods used for prophylaxis, and an overview of published guidelines are presented.

Peri-procedural management of patients taking oral anticoagulants

The use of oral anticoagulants is becoming increasingly common. For many years warfarin was the main oral anticoagulant available, but therapeutic options have expanded with the introduction of oral direct thrombin (dabigatran) and factor Xa inhibitors (apixaban, rivaroxaban, and edoxaban). Management of patients taking any oral anticoagulant in the peri-procedural period poses a challenge to medical and surgical providers because of the competing risks of thrombosis and hemorrhage. Bridging therapy has been used to minimize time without anticoagulation when warfarin is interrupted for invasive procedures, but validated strategies based on high quality data are lacking. Existing data suggest that the use of bridging therapy may increase the risk of bleeding for some patients without reducing the risk of thrombosis. Clinical trials are currently under way to answer these questions. Because the half lives and time to anticoagulant activity of newer oral anticoagulants are shorter than for warfarin, bridging therapy is not thought to be necessary with these agents. Peri-procedural management of patients taking these agents is complicated by the lack of demonstrated reversal agents in emergency situations, although specific antidotes are being developed and tested. Existing guidelines for peri-procedural management of patients on oral anticoagulants highlight the importance of individualized patient decision making and suggest strategies to minimize complications. From a patient's perspective, given the uncertainties surrounding optimal management, explicit discussions regarding risks and benefits of treatment options and demonstration of effective communication among medical and surgical providers are essential.

A systematic approach to the preoperative medical evaluation of adults

The number, age, and medical complexity of patients undergoing elective noncardiac surgery is rising worldwide. Internists, family physicians, and midlevel providers asked to perform preoperative medical evaluations. However, lack of consensus has led to wide variation in practice in what is included and addressed in these evaluations, and the efficacy of these assessments has been debated. The intended purpose of the evaluation seems to be universally accepted as aiming to assess and identify risks associated with the patient's comorbid medical conditions and the specific surgical procedure. The goal is to minimize those risks. Herein, we propose a systematic approach to the preoperative medical evaluation based on the best available evidence and expert opinion, with an emphasis on identifying all potentially pertinent patient- and surgery-specific risk factors.

Comparison of the quality of patient referrals from physicians, physician assistants, and nurse practitioners

OBJECTIVE

To compare the quality of referrals of patients with complex medical problems from nurse practitioners (NPs), physician assistants (PAs), and physicians to general internists.

PATIENTS AND METHODS

We conducted a retrospective comparison study involving regional referrals to an academic medical center from January 1, 2009, through December 31, 2010. All 160 patients referred by NPs and PAs combined and a random sample of 160 patients referred by physicians were studied. Five experienced physicians blinded to the source of referral used a 7-item instrument to assess the quality of referrals. Internal consistency, interrater reliability, and dimensionality of item scores were determined. Differences between item scores for patients referred by physicians and those for patients referred by NPs and PAs combined were analyzed by using multivariate ordinal logistical regression adjusted for patient age, sex, distance of the referral source from Mayo Clinic, and Charlson Index.

RESULTS

Factor analysis revealed a 1-dimensional measure of the quality of patient referrals. Interrater reliability (intraclass correlation coefficient for individual items: range, 0.77-0.93; overall, 0.92) and internal consistency for items combined (Cronbach α=0.75) were excellent. Referrals from physicians were scored higher (percentage of agree/strongly agree responses) than were referrals from NPs and PAs for each of the following items: referral question clearly articulated (86.3% vs 76.0%; P=.0007), clinical information provided (72.6% vs 54.1%; P=.003), documented understanding of the patient's pathophysiology (51.0% vs 30.3%; P<.0001), appropriate evaluation performed locally (60.3% vs 39.0%; P<.0001), appropriate management performed locally (53.5% vs 24.1%; P<.0001), and confidence returning patient to referring health care professional (67.8% vs 41.4%; P<.0001). Referrals from physicians were also less likely to be evaluated as having been unnecessary (30.1% vs 56.2%; P<.0001).

CONCLUSION

The quality of referrals to an academic medical center was higher for physicians than for NPs and PAs regarding the clarity of the referral question, understanding of pathophysiology, and adequate prereferral evaluation and documentation.

Incidence of venous thromboembolism after elective knee arthroscopic surgery: a historical cohort study

BACKGROUND

The incidence of symptomatic venous thromboembolism (VTE) after knee arthroscopy is uncertain.

OBJECTIVES

To estimate the incidence of symptomatic VTE after arthroscopic knee surgery.

METHODS

In a population-based historical cohort study, all Olmsted County, MN, USA, residents undergoing a first arthroscopic knee surgery during the 18-year period of 1988-2005 were followed for incident deep venous thrombosis or pulmonary embolism. The cumulative incidence of VTE after knee arthroscopy was determined using the Kaplan-Meier product limit estimator. Patient age at surgery, sex, calendar year of surgery, body mass index, anesthesia characteristics, and hospitalization were tested as potential predictors of VTE using Cox proportional hazards modeling, both univariately and adjusted for age and sex.

RESULTS

Among 4833 Olmsted County residents with knee arthroscopy, 18 developed postoperative VTE, all within the first 6 weeks after surgery. The cumulative incidence rates of symptomatic VTE at 7, 14, and 35 days were 0.2%, 0.3%, and 0.4%, respectively. The hazard for postoperative VTE was significantly increased for older patient age (hazard ratio = 1.34 for each 10-year increase in patient age; P = 0.03) and hospitalization either before or after knee arthroscopy (hazard ratio = 14.1; P < 0.001).

CONCLUSIONS

The incidence of symptomatic VTE after arthroscopic knee surgery is very low. Older age and hospitalization are associated with increased risk. Routine prophylaxis to prevent symptomatic VTE is likely not needed in this patient population.

Preoperative testing before noncardiac surgery: guidelines and recommendations

Preoperative testing (e.g., chest radiography, electrocardiography, laboratory testing, urinalysis) is often performed before surgical procedures. These investigations can be helpful to stratify risk, direct anesthetic choices, and guide postoperative management, but often are obtained because of protocol rather than medical necessity. The decision to order preoperative tests should be guided by the patient's clinical history, comorbidities, and physical examination findings. Patients with signs or symptoms of active cardiovascular disease should be evaluated with appropriate testing, regardless of their preoperative status. Electrocardiography is recommended for patients undergoing high-risk surgery and those undergoing intermediate-risk surgery who have additional risk factors. Patients undergoing low-risk surgery do not require electrocardiography. Chest radiography is reasonable for patients at risk of postoperative pulmonary complications if the results would change perioperative management. Preoperative urinalysis is recommended for patients undergoing invasive urologic procedures and those undergoing implantation of foreign material. Electrolyte and creatinine testing should be performed in patients with underlying chronic disease and those taking medications that predispose them to electrolyte abnormalities or renal failure. Random glucose testing should be performed in patients at high risk of undiagnosed diabetes mellitus. In patients with diagnosed diabetes, A1C testing is recommended only if the result would change perioperative management. A complete blood count is indicated for patients with diseases that increase the risk of anemia or patients in whom significant perioperative blood loss is anticipated. Coagulation studies are reserved for patients with a history of bleeding or medical conditions that predispose them to bleeding, and for those taking anticoagulants. Patients in their usual state of health who are undergoing cataract surgery do not require preoperative testing.

Cancer effect on periprocedural thromboembolism and bleeding in anticoagulated patients

BACKGROUND

Patients with active cancer are often on chronic anticoagulation and frequently require interruption of this treatment for invasive procedures. The impact of cancer on periprocedural thromboembolism (TE) and major bleeding is not known.

PATIENTS AND METHODS

Two thousand one hundred and eighty-two consecutive patients referred for periprocedural anticoagulation (2484 procedures) using a standardized protocol were followed forward in time to estimate the 3-month incidence of TE, major bleeding and survival stratified by anticoagulation indication. For each indication, we tested active cancer and bridging heparin therapy as potential predictors of TE and major bleeding.

RESULTS

Compared with patients without cancer, active cancer patients (n=493) had more venous thromboembolism (VTE) complications (1.2% versus 0.2%; P=0.001), major bleeding (3.4% versus 1.7%; P=0.02) and reduced survival (95% versus 99%; P<0.001). Among active cancer patients, only those chronically anticoagulated for VTE had higher rates of periprocedural VTE (2% versus 0.16%; P=0.002) and major bleeding (3.7% versus 0.6%; P<0.001). Bridging with heparin increased the rate of major bleeding in cancer patients (5% versus 1%; P=0.03) without impacting the VTE rate (0.7% versus 1.4%, P=0.50).

CONCLUSIONS

Cancer patients anticoagulated for VTE experience higher rates of periprocedural VTE and major bleeding. Periprocedural anticoagulation for these patients requires particular attention to reduce these complications.

Service census caps and unit-based admissions: resident workload, conference attendance, duty hour compliance, and patient safety

OBJECTIVE

To examine the effect of census caps and unit-based admissions on resident workload, conference attendance, duty hour compliance, and patient safety.

PARTICIPANTS AND METHODS

We implemented a census cap of 14 patients on 6 Mayo Clinic internal medicine resident hospital services and a unit-based admissions process in which patients and care teams were consolidated within hospital units. All 280 residents and 15,926 patient admissions to resident and nonresident services 1 year before the intervention (September 1, 2006, through August 31, 2007) and 1 year after the intervention (May 1, 2008, through April 30, 2009) were included. Residents' workload, conference attendance, and duty hours were tracked electronically. Patient safety variables including Rapid Response Team and cardiopulmonary resuscitation events, intensive care unit transfers, Patient Safety Indicators, and 30-day readmissions were compared preintervention and postintervention.

RESULTS

After the intervention, residents' mean (SE) ratings of workload appropriateness improved (3.10 [0.08] vs 3.87 [0.08] on a 5-point scale; P<.001), as did conference attendance (1523 [56. 8%] vs 1700 [63.5%] conferences attended; P<.001). Duty hour violations for working more than 30 consecutive hours and not having 10 hours off between duty periods decreased from 77 of 9490 possible violations (0.81%) to 27 (0.28%) and from 70 (0.74%) to 14 (0.15%) violations, respectively (both, P<.001). Thirty-day readmissions to resident services decreased (1010 [18.14%] vs 682 [15. 37%]; P<.001). All other patient safety measures remained unchanged. After adjustment for illness severity, there were no significant differences in patient outcomes between resident and nonresident services.

CONCLUSION

Census caps and unit-based admissions were associated with improvements in resident workload, conference attendance, duty hour compliance, and readmission rates while patient outcomes were maintained.

Periprocedural Anticoagulation Management of Patients With Venous Thromboembolism

Objective— Patients with venous thromboembolism (VTE) often require temporary warfarin interruption for an invasive procedure. The incidence of thromboembolism and bleeding related to periprocedural anticoagulation management of such patients is unknown.

Methods and Results— In a protocol-driven, inception cohort design study, all VTE patients (n=775) referred for periprocedural anticoagulation management (1997–2007) were followed-up to estimate the 3-month cumulative incidence of thromboembolism and bleeding. Patients were stratified by thrombus acuity (acute, <30 days; subacute, 31–90 days; or chronic ≥91 days). Decisions to provide “bridging” low-molecular-weight heparin were based on estimated thromboembolism and bleeding risk. Low-molecular-weight heparin was more often administered in acute (87%) and subacute (81%) VTE compared to chronic VTE (59%; P <0.001). The 3-month cumulative incidence of thromboembolism (1.8%), major hemorrhage (1.8%), and mortality (1.7%) were low and did not differ by management strategy. Active cancer was the only independent predictor of thrombotic recurrence (HR, 4.86; 95% CI, 1.6–14.5; P =0.005), major hemorrhage (HR, 6.8; 95% CI, 2.1–21.7; P =0.001), and death (HR, 32.7; 95% CI, 4.3–251.2; P =0.0008).

Conclusion— Thromboembolism, bleeding, and death among VTE patients in whom anticoagulation is temporarily interrupted for an invasive procedure is low. Cancer patients require particular care given their propensity for both clotting and bleeding.

Periprocedural anticoagulation management of patients with nonvalvular atrial fibrillation

OBJECTIVE

To estimate the 3-month cumulative incidence of thromboembolism (TE), bleeding, and death among consecutive patients with nonvalvular atrial fibrillation (AF) who were receiving long-term anticoagulation therapy and were referred to the Thrombophilia Center at Mayo Clinic for periprocedural anticoagulation management.

PATIENTS AND METHODS

In a prospective cohort study of consecutive patients receiving long-term anticoagulation therapy who were referred to the Thrombophilia Center for periprocedural anticoagulation management over the 7-year period, January 1, 1997, to December 31, 2003, 345 patients with nonvalvular AF were eligible for inclusion. Warfarin was stopped 4 to 5 days before and was restarted after surgery as soon as hemostasis was assured. The decision to provide bridging therapy with heparin was individualized and based on the estimated risks of TE and bleeding.

RESULTS

The 345 patients with AF (mean +/- SD age, 74+/-9 years; 33% women) underwent 386 procedures. Warfarin administration was not interrupted for 44 procedures. Periprocedural heparin was provided for 204 procedures. Patients receiving heparin were more likely to have prior TE (43% vs 24%; P<.001) and a higher CHADS2 (congestive heart failure, hypertension, age, diabetes, stroke) score (2.2 vs 1.9; P=.06). Four patients had 6 episodes of TE (3 strokes and 3 acute coronary episodes; TE rate, 1.1%; 95% confidence interval, 0.0%-2.1%). Nine patients had 10 major bleeding events (major bleeding rate, 2.7%; 95% confidence interval, 1.0%-4.4%). There were no deaths. Neither bleeding nor TE rates differed by anticoagulant management strategy.

CONCLUSION

The 3-month cumulative incidence of TE and bleeding among patients with AF in whom anticoagulation was temporarily interrupted for an invasive procedure was low and was not significantly influenced by bridging therapy.

Evaluation of a quantitative D-dimer latex immunoassay for acute pulmonary embolism diagnosed by computed tomographic angiography

OBJECTIVE

To determine the sensitivity and specificity of a quantitative plasma fibrin D-dimer latex immunoassay (LIA) for the diagnosis of acute pulmonary embolism.

SUBJECTS AND METHODS

Study subjects were Mayo Clinic Rochester inpatients and outpatients with suspected acute pulmonary embolism; all had undergone quantitative D-dimer LIA testing and multidetector-row computed tomographic (CT) angiography between August 3, 2001, and November 10, 2003. Multidetector-row CT angiography was the diagnostic reference standard.

RESULTS

Of 1355 CT studies, 208 (15%) were positive for acute pulmonary embolism. Median D-dimer levels were significantly higher for patients with acute pulmonary embolism (1425 ng/mL) than for patients without (500 ng/mL) (P<.001). The highest specificity that optimizes sensitivity for acute pulmonary embolism was achieved by using a discriminant value of 300 ng/mL, which yielded a sensitivity of 0.94 (95% confidence interval [CI], 0.89-0.97), a specificity of 0.27 (95% CI, 0.25-0.30), and a negative predictive value of 0.96 (95% CI, 0.93-0.98).

CONCLUSION

The quantitative D-dimer LIA with a discriminant value of 300 ng/mL had high sensitivity and high negative predictive value but low specificity for the diagnosis of acute pulmonary embolism. On the basis of these results, we believe that a negative quantitative D-dimer LIA result and a low pretest probability of thromboembolism together are sufficient to exclude acute pulmonary embolism.

Therapy Insight: management of urology patients taking long-term warfarin anticoagulation therapy

Chronic warfarin anticoagulation is commonly used to prevent thromboembolism in patients with atrial fibrillation or venous thromboembolism, and in the management of patients with mechanical heart valves. Interruption of long-term anticoagulation therapy for elective, planned urologic procedures in these patients creates a complex situation in which competing risks of thrombosis and hemorrhage must be managed; when anticoagulation is withheld patients are at risk of thrombosis, and when it is restarted they are at risk of hemorrhage. Patients at a high risk of thrombosis are typically given bridging therapy with heparin to reduce the amount of time without anticoagulation. Outcomes from bridging therapy are influenced by patient characteristics, including the risk of thromboembolism from underlying medical conditions and the risk of perioperative bleeding, and by characteristics of the procedures themselves. The safety and efficacy of different approaches are not well documented. Data regarding periprocedural anticoagulation management of urology patients is limited and principally describes outcomes related to transurethral prostate surgery. Results from these studies indicate that various strategies of anticoagulation interruption and bridging therapy result in low frequencies of thromboembolism, but variable rates of hemorrhage. Patients on anticoagulation therapy who are due to undergo invasive urologic procedures that have a low risk of developing thromboembolism can discontinue warfarin 4-5 days before the procedure, and resume it postprocedure. Bridging therapy to prevent thrombosis is necessary for patients at a higher risk of developing thromboembolism. Future research should develop strategies to maintain low rates of thrombosis but reduce the frequency of postoperative hemorrhage.

Familial aggregation of hypertension treatment and control in the Genetic Epidemiology Network of Arteriopathy (GENOA) study

PURPOSE

To assess if the treatment and control of hypertension aggregates in families.

METHODS

The Genetic Epidemiology Network of Arteriopathy (GENOA) study enrolled sibships between 1997 and 1999, including 1329 hypertensive non-Hispanic blacks (1057 sibling pairs) from Jackson, Mississippi, 1133 hypertensive non-Hispanic whites (859 sibling pairs) from Rochester, Minnesota, and 752 hypertensive Hispanic whites (627 sibling pairs) from Starr County, Texas. Hypertension awareness and drug treatment were ascertained at examination; control was defined by blood pressure levels <140/90 mm Hg. As a measure of familial aggregation, odds ratios were calculated to assess concordance between sibling pairs in the treatment and control of hypertension.

RESULTS

Overall, 90.5% of subjects were aware of their hypertension; 90.6% of those who were aware were treated with antihypertensive drugs and 56.0% of those treated had their hypertension controlled. There was statistically significant sib-sib concordance in the treatment of hypertension (odds ratio [OR] = 1.61; 95% confidence interval [CI]: 1.25 to 2.47; P = 0.003) and in the control of drug-treated hypertension (OR = 1.51; 95% CI: 1.25 to 1.81; P <0.0001).

CONCLUSION

These findings suggest that the treatment and control of hypertension aggregates in families.

Giant cell myocarditis as a manifestation of drug hypersensitivity

Adverse drug effects on the myocardium are often classified into toxic and hypersensitivity forms of myocarditis, each with distinct histologic findings. In contrast, giant cell myocarditis (GCM) is generally not associated with adverse drug reactions and has unique histopathologic features. We report four cases of adverse drug reactions in which the histologic findings were characteristic of GCM. The clinical recognition that GCM may be a manifestation of an adverse drug reaction is important, since the prognosis and treatment of this entity may be different from that of other forms of myocarditis.

Characterization of the interactions of human papillomavirus type 16 E6 with p53 and E6-associated protein in insect and human cells

Human papillomavirus (HPV) 16 E6 induces the degradation of the tumour suppressor protein p53 by the ubiquitin-dependent proteolysis pathway. In vitro, this process involves the formation of a trimolecular complex between E6, p53 and a cellular protein E6-associated protein (E6-AP). However, an analysis of their potential interactions in vivo has not been carried out. We have established a model for the expression and analysis of the interactions of these three proteins in insect cells, a eukaryotic system where potentially crucial modifications of the proteins will occur. In baculovirus-infected cells the degradation of p53 can occur. However, p53 is only degraded early in the infectious cycle due to a lack of ATP at later times. Consequently, substantial quantities of material can be produced in this system for further analysis. Evidence is also provided that, in vivo, E6 can interact with p53 in the absence of E6-AP and that E6-AP can interact with p53 in the absence of E6. Furthermore, analysis of the subcellular localization of the proteins using both biochemical fractionation and indirect immunofluorescence suggests that the degradation of p53 occurs in the perinuclear region of the cell.

Molecular analysis of the interaction between HPV type 16 E6 and human E6-associated protein

The complex formed between the human papillomavirus type 16 E6 protein and human E6-associated protein, which combine to ubiquitylate and degrade p53, has been studied by chemical crosslinking. Analysis of the interactions of proteins purified from Escherichia coli as well as proteins expressed in insect cells indicates that, while E6 has the capacity to form dimers, E6 and E6-associated protein interact as two monomers to form a heterologous dimer.