Meta-Analysis to Assess the Quality of International Normalized Ratio Control and Associated Outcomes in Venous Thromboembolism Patients

Introduction

Patients with venous thromboembolism (VTE) frequently require vitamin K antagonists (VKAs) to prevent recurrent events, but their use increases hemorrhage risk. We performed a meta-analysis to assess the quality of international normalized ratio (INR) control, identify study-level predictors of poor control and to examine the relationship between INR control and adverse outcomes in VTE patients.

Materials and Methods

We searched bibliographic databases (1990-June 2013) for studies of VTE patients receiving adjusted-dose VKAs that reported time in range (2.0-3.0) or proportion of INRs in range and/or reported INR measurements coinciding with thromboembolic or hemorrhagic events. Meta-analysis and meta-regression analysis was performed.

Results

Upon meta-analysis, studies found 59% (95%CI: 54-64%) of INRs measured and 61% (95%CI: 59-63%) of the time patients were treated were spent outside the target range of 2.0-3.0; with a tendency for under- versus over-anticoagulation. Moreover, this poor INR control resulted in a greater chance of recurrent VTE (beta-coefficient = -0.46, p = 0.01) and major bleeding (beta-coefficient = -0.30, p = 0.02). Patients with an INR < 2.0 made up 58% (95%CI: 39-77%) of VTE cases, while those with an INR > 3.0 made up 48% (95%CI: 34-61%) of major hemorrhage cases. Upon meta-regression, being VKA-naïve (-14%, p = 0.04) and treated in the community (-7%, p < 0.001) were associated with less time in range, while being treated in Europe/United Kingdom (compared to North America) was associated with (11%, p = 0.003) greater time.

Conclusions

Strategies to improve INR control or alternative anticoagulants, including the newer oral agents, should be widely implemented in VTE patients to reduce the rate of recurrent events and bleeding.     

Indirect treatment comparison of new oral anticoagulants for the treatment of acute venous thromboembolism

Background

Numerous new oral anticoagulants (NOACs) have been compared to a parenteral anticoagulant/oral vitamin K antagonist (VKA) for the treatment of acute venous thromboembolism (VTE). We aimed to conduct a systematic review and adjusted indirect comparison meta-analysis to compare the efficacy and safety of NOACs for this indication.

Methods

We conducted a systematic literature search through November 2013 for randomized trials that evaluated treatment of acute VTE with a NOAC including rivaroxaban, apixaban, dabigatran and edoxaban. Trials had to report at least one of the following outcomes of interest: mortality, recurrent VTE, recurrent pulmonary embolism (PE), recurrent deep vein thrombosis (DVT), or major bleeding. Included trials were evaluated for quality using the Cochrane Risk of Bias tool. We performed an adjusted indirect comparison meta-analysis to evaluate the comparative efficacy and safety of NOACs, reporting relative risks (RRs) and 95% confidence intervals for each outcome.

Results

Six trials (n = 27,069) met inclusion criteria, one each evaluating apixaban and edoxaban and two trials each evaluating rivaroxaban and dabigatran. Risk of bias was low for all trials. NOACS did not differ significantly in the risk of mortality, recurrent VTE, recurrent PE or recurrent DVT. Dabigatran increased major bleeding risk compared to apixaban [RR 2.69 (1.19 to 6.07)] as did edoxaban compared to apixaban [RR 2.74 (1.40 to 5.39)].

Conclusion

Although NOACs do not appear to differ in the efficacy of treating acute VTE, data suggests apixaban to be the safer than some of its competitors.     

Thromboprophylaxis use and concordance with guidelines among medical and surgical patients in Morocco

Introduction

No data are available on thromboprophylaxis use in Morocco. Our aim was to characterize patients at risk of venous thromboembolism and assess the rate of appropriate thromboprophylaxis.

Materials and Methods

This was a national, observational, multicentre survey of venous thromboembolism risk and thromboprophylaxis use in hospitalized patients. Data were collected on a predefined date in three university hospitals in Morocco using a standardized pre-printed form. Thromboembolic risk was assessed according to the American College of Chest Physicians (ACCP) 2008 guidelines. Patients were classified as “thromboprophylaxis indicated” or “thromboprophylaxis not indicated”.

Results

784 patients were analysed: 307 (39.2%) medical and 477 (60.8%) surgical. 421 (53.7%) were female. Medical patients were older than surgical patients (57.6 ± 11.5 vs. 46.2 ± 16.9 years, p < 0.0001) and were more likely to have risk factors for thromboembolism (50.5% vs. 45.7% of patients, p = NS). 57% of patients without contraindications or bleeding risk were at risk of thromboembolism according to ACCP guidelines and thromboprophylaxis was prescribed to 42.8% of these patients. In contrast, 7.4% of patients with no thromboembolic risk also received thromboprophylaxis (proportion agreement: 61.0%; Kappa = 0.296). Over half (54.5%) of medical patients at risk of thromboembolism did not receive thromboprophylaxis whereas 6.3% of those with no risk did receive it (proportion agreement: 76.4%; Kappa = 0.433). These figures were 57.9% and 9.2%, respectively, for surgical patients (proportion agreement: 52.7%; Kappa = 0.191). Thromboprophylaxis was given to 19.2% of patients with contraindications or a bleeding risk.

Conclusions

Educational initiatives are imperative to inform doctors about appropriate thromboprophylaxis.     

Population-based epidemiology of postoperative venous thromboembolism in Taiwanese patients receiving hip or knee arthroplasty without pharmacological thromboprophylaxis

Introduction

Population-based evaluation on the incidence of postoperative venous thromboembolism (VTE) has not yet been reported for Asians receiving arthroplasty. In Taiwan, thromboprophylaxis was not commonly applied for patients. The population-based cohort study aimed to investigate the epidemiology, and to determine the risk factors VTE for patients receiving hip or knee replacement without pharmacological thromboprophylaxis in Taiwan.

Materials and Methods

We retrospectively acquired patients’ data from National Health Insurance databases representing more than 99% of about 23 million Taiwanese citizens. The primary outcome was the incidence of composite symptomatic VTE within 28 days after receiving hip or knee replacement surgery.

Results

During 2002 to 2006, there were 114,026 patients undergoing hip (n = 61,460) or knee (n = 52,566) replacement surgery. The occurrence rate of overall postoperative VTE was 0.44%. The incidence of pulmonary embolism was four in 10,000 patients receiving hip replacement or seven in 10,000 individuals undergoing knee replacement. The weekly cumulative incidence of VTE was persistently rising up to 28 days after surgery. Dramatic increase in risk of post-surgical VTE was associated with prior disease history of PE (p < 0.001 for hip replacement, p = 0.01 for knee replacement) or DVT (p = 0.004 for hip replacement, p < 0.001 for knee replacement). Prior claim of congestive heart failure was an independent risk factor associated with patients receiving knee arthroplasty (p = 0.01).

Conclusion

Life-threatening PE occurred and increased cumulatively up to 28 days after hip or knee arthroplasty in Asians. Proper prophylaxis for patients with the exposure of high risks needs to be scrutinized.     

Tamoxifen induces resistance to activated protein C

Introduction

The estrogen antagonist tamoxifen (TAM) increases the thrombotic risk similar to estrogen containing oral contraceptives (OC). In OC users this risk is attributed to alterations of hemostasis resulting in acquired resistance to activated protein C (APC). TAM-induced APC resistance has not been reported yet.

Materials and Methods

Blood samples were collected prospectively from women with breast cancer before (n = 25) and monthly after start of adjuvant TAM treatment (n = 75). APC resistance was evaluated on basis of the effect of APC on the endogenous thrombin generation potential. To detect increased in vivo APC generation APC plasma levels were measured using a highly sensitive oligonucleotide-based enzyme capture assay. Routine hemostasis parameters were measured additionally.

Results

APC sensitivity decreased by 41% (p = 0.001) compared to baseline after one month of TAM application and remained significantly decreased during the study period. Free protein S increased (p = 0.008) while other analyzed procoagulant factors, inhibitors, and activation markers of coagulation decreased or did not change significantly. In five patients the APC concentration increased to non-physiological levels but an overall significant increase of APC was not observed.

Conclusions

This is the first study showing acquired APC resistance under TAM therapy. Acquired APC resistance might explain the increased thrombotic risk during TAM treatment. Observed changes of hemostasis parameters suggest different determinants of TAM-induced APC resistance than in OC-induced APC resistance. The presence of acquired APC resistance in TAM patients warrants further evaluation if these patients may benefit from antithrombotic prophylaxis in the presence of additional thrombotic risk factors.     

Increased Risk of Deep Vein Thrombosis and Pulmonary Thromboembolism in Patients with Spinal Cord Injury: A Nationwide Cohort Prospective Study

Background

We investigated the effect of spinal cord injury (SCI) on the development of deep vein thrombosis (DVT) and pulmonary thromboembolism (PE) by conducting a nationwide longitudinal cohort study.

Methods

We studied the entire hospitalized population in Taiwan for the 1998–2008 period, with a follow-up period extending to the end of 2010. We identified SCI patients using the Taiwan National Health Insurance Research Database (NHIRD), and selected a cohort that was 1:4 frequency-matched by age (5-y span), sex, and index year from the general population. We analyzed the risks of DVT and PE using Cox proportional-hazards regression models, which included the demographic variables of sex, age, and comorbidities.

Results

A total of 47,916 SCI patients (62.7% men, mean age of 50.0 y) and 191,664 controls were followed for 308,266 and 1,341,169 person-years, respectively. The adjusted hazard ratio (HR) of DVT and PE development was 2.46-fold and 1.57-fold among the SCI patients, respectively. The highest risk of DVT and PE developed within 3 months after an SCI occurred (HR: 16.9 and 3.64, respectively). The adjusted HR of DVT and PE rose markedly with increasing age. The adjusted HR of DVT was highest among C-spine SCI patients, and the adjusted HR of PE was highest among T-spine SCI patients.

Conclusion

This nationwide prospective cohort study demonstrated that the risk of DVT and PE increased significantly in SCI patients compared with that of the general population. The highest risk of DVT and PE developed within 3 months after an SCI occurred.     

Validity of standard gamble estimated quality of life in acute venous thrombosis

Introduction

The standard gamble is considered the ‘gold standard’ technique for measuring quality of life. We recently used the standard gamble to estimate quality of life in acute venous thrombosis, and found unexpected variability in the responses. The current study aimed to explore the reasons for variability by comparing the standard gamble technique in patients with acute venous thrombosis to other quality of life measurement tools.

Materials and Methods

Thrombosis clinic patients treated for venous thrombosis were eligible to participate. Patients evaluated their current health state by performing a standard gamble interview, reporting on a visual analogue scale, completing the SF-36 and disease specific questionnaires (PEmb-Qol and VEINES-QOL/Sym). Validity was assessed by correlating the standard gamble utilities with the other methods. Test-retest reliability, responsiveness and acceptability were also assessed.

Results

Forty-four patients were interviewed, with 16 attending for a repeat interview. The median standard gamble utility was 0.97 (0.84-1.0), SF-6D 0.64 (0.59 - 0.80) and visual analogue score 70 (60 - 80). Participants with pulmonary embolism had lower standard gamble estimates than those with deep vein thrombosis. There was good discriminant validity in that the standard gamble estimates were not associated with risk taking behavior, negative outlook, sex or education. Test-retest reliability with the standard gamble was moderate and there was evidence of a ceiling effect.

Conclusions

Standard gamble utilities are higher than other methods of measuring quality of life in venous thrombosis. The choice of utility values adopted in studies will impact on future economic studies.     

Increased activation of blood coagulation in pregnant women with the Factor V Leiden mutation

Background

The risk of venous thromboembolism is enhanced in pregnant carriers of the Factor V Leiden mutation. The primary aim of the study was to compare prothrombin fragments 1 + 2, soluble fibrin and D-dimer levels in pregnant Factor V Leiden mutation carriers with those in non-carriers. Secondary aims were to evaluate whether these biomarkers could predict placenta-mediated complications or venous thromboembolism, and to study blood coagulation after caesarean section with thromboprophylaxis and after vaginal delivery without thromboprophylaxis.

Material/Methods

Prothrombin fragments 1 + 2, soluble fibrin and D-dimer levels were studied longitudinally in 476 carriers with singleton pregnancies from gestational weeks 23–25 until 8–10 weeks postpartum.

Results

Prothrombin fragments 1 + 2 and D-dimer levels gradually increased during pregnancy. D-dimer levels were higher in carriers, both during pregnancy and puerperium, compared to non-carriers. D-dimer levels above 0.5 mg/l were found in about 30% and 20% of the heterozygous carriers at 4–5 and 8–10 weeks postpartum, respectively. Soluble fibrin levels were mainly unchanged during pregnancy, with no difference between carriers and non-carriers. Biomarker levels were similar in carriers with uncomplicated and complicated pregnancies.

Conclusion

Higher D-dimer levels indicate increased blood coagulation and fibrinolysis activity in carriers. The high proportion of carriers with D-dimer levels exceeding 0.5 mg/l postpartum must be considered when assessing the probability of venous thromboembolism. Large overlaps in biomarker levels in normal and complicated pregnancies suggest that these biomarkers cannot be used as predictors. Thromboprophylaxis following caesarean section may prevent increased activation of blood coagulation.     

A case series of LMWH use in pregnancy: Should trough anti-Xa levels guide dosing?

Introduction

Pregnancy is a thrombogenic state, increasing the risk for venous thromboembolism (VTE), and the risk of valve thrombosis amongst women with mechanical heart valves (MHV). While low molecular weight heparins (LMWH) are generally dosed based on weight (i.e., enoxaparin 1 mg/kg every 12 hours), data in pregnant women have shown that weight-based dosing does not consistently achieve target anti-Xa levels. In women with MHV, our practice includes titrating LMWH doses to target both trough and peak anti-Xa levels, while for those with VTE peak anti-Xa levels guide dosing.

Materials/Methods

This retrospective case series included pregnant women requiring LMWH treatment doses with at least 3 peak (+/− trough) anti-Xa levels. Our primary objective was to describe the actual LMWH dose required to achieve targeted anti-Xa levels relative to weight-based dosing in patients with MHV. Secondarily, we compared the same for VTE patients; compared actual dosing between those with MHV and VTE; and examined maternal and fetal outcomes.

Results/Conclusion

Women with MHV (N = 4) required greater than weight-based dosing of enoxaparin (1.35 mg/kg Q12H) to achieve targeted anti-Xa levels. Importantly, achieving target peak anti-Xa levels did not always ensure maintenance of minimum trough levels. VTE patients (N = 12) did not require more enoxaparin (0.96 mg/kg Q12H) than weight based dosing. MHV patients received more enoxaparin compared to VTE patients (P < 0.001). No bleeding or clotting complications were associated with LMWH administration. In pregnant women with MHV at high risk of thromboembolism, LMWH dosing guided by trough and peak anti-Xa levels should be considered.     

Screening high-risk cancer patients for VTE: A prospective observational study

Background

The utility of screening for venous thromboembolism (VTE) in cancer patients is unknown. We evaluated this in a prospective cohort study of cancer patients initiating a new chemotherapy regimen and deemed high-risk (score ≥ 3) based on a validated Risk Score.

Methods

Patients were evaluated with baseline and Q4 (± 1) week serial ultrasonography for up to 16 weeks; additionally, computed tomography scans for restaging were also evaluated for VTE.

Results

The study population comprised 35 patients. Pancreatic and gastro-esophageal cancers were the most common diagnoses. Of these, 8 (23%) developed a VTE. This included 5 patients with DVT alone (14%), 1 patient with PE alone (3%) and 2 (6%) with both. Ultrasound examinations identified asymptomatic DVT in 9.3% of patients at baseline; 0% at weeks 4 and 8 and 5.6% at week 12. Restaging CT scans identified asymptomatic PE in one patient at week 6 and in one patient at week 9 with subsequent DVT at week 10.

Conclusions

Screening for asymptomatic VTE has not been previously used as a clinical strategy in ambulatory cancer patients. We report that one-tenth of patients at baseline had occult DVT and in this high-risk population, screening at baseline may be of value.