A comparison of red blood cell transfusion utilization between anti-activated factor X and activated partial thromboplastin monitoring in patients receiving unfractionated heparin

Pleiotropic Effects of Heparin and its Monitoring in the Clinical Practice

Unfractionated heparin (UFH) was uncovered in 1916, has been used as an anticoagulant since 1935, and has been listed in the World Health Organization's Model List of Essential Medicines. Despite the availability of many other anticoagulants, the use of heparin (either low molecular weight heparin [LMWH] or UFH) is still substantial. Heparin has pleotropic effects including anticoagulant and several nonanticoagulant properties such as antiproliferative, anti-inflammatory activity, and anticomplement effects. Although UFH has been widely replaced by LMWH, UFH is still the preferred anticoagulant of choice for patients undergoing cardiopulmonary bypass surgery, extracorporeal membrane oxygenation, and patients with high-risk mechanical cardiac valves requiring temporary bridging with a parenteral anticoagulant. UFH is a highly negatively charged molecule and binds many positively charged molecules, hence has unpredictable pharmacokinetics, and variable anticoagulant effect on an individual patient basis. Therefore, anticoagulant effects of UFH may not be proportional to the dose of UFH given to any individual patient. In this review, we discuss the anticoagulant and nonanticoagulant activities of UFH, differences between UFH and LMWH, when to use UFH, different methods of monitoring the anticoagulant effects of UFH (including activated partial thromboplastin time, heparin anti-Xa activity level, and activated clotting time), while discussing pros and cons related to each method and comparison of clinical outcomes in patients treated with UFH monitored with different methods based on available evidence.

Structure comparison and anti-coagulant effects of the glycosaminoglycans from porcine duodenum and jejunum

To make full use of the porcine sources and develop better choice of novel GAGs as anti-coagulants, two fractions of GAGs from the porcine jejunum (A) and duodenum (C) have been separated & purified. The products were further sulfated to give B and D in order to test the influence of sulfate pattern on the bioactivity. The results showed that the relative molecular weight range of A was 3000-50,000 (Mw, g/mol), whereas C had an average molecular weight of 75,885 (Mw, g/mol). A was identified as a novel heparan sulfate through enzymatic hydrolysis analysis. C was a chondroitin like polysaccharide mainly composed of β-d-GlcA-(1 → 4) and β-d-GalNAc-(1 → 3). A possessed controllable anti-coagulant activity (7 IU/mg) in vitro. The activity of D almost achieved the same magnitude of A. This study demonstrated the anticoagulant potential of the polysaccharides, providing solid foundation for development of anti-coagulants from porcine intestine.

Improving safety of unfractionated heparin: a retrospective, quasi-experimental, observational study of the impact of a pocket card and a computerised prescription aid tool in the University Hospitals of Geneva

BACKGROUND

Despite the rapid rise of direct oral anticoagulants, unfractionated heparin (UFH) remains the mainstay anticoagulant in specific situations such as severe renal failure, perioperative setting or in critical care units. However, its titration is often challenging.

OBJECTIVES

To investigate the effect of a pocket card and a computerised prescription aid tool (CPAT) on the quality of UFH anticoagulation.

DESIGN

Monocentric retrospective, quasi-experimental, observational study.

SETTING

Inpatient primary care centre between 1 January 2016 and 31 December 2019.

PARTICIPANTS

>18 years-old treated with therapeutic UFH for more than 24 hours. There were 819 and 1169 anticoagulation episodes before and after intervention, respectively.

INTERVENTION

In October 2017, we implemented a pocket card with evidence-based recommendation for therapeutic UFH initiation, monitoring and dosing adaptation. In October 2019, we implemented a CPAT in a group subset.

PRIMARY AND SECONDARY OUTCOMES

The primary outcome was the time needed to reach a therapeutic anti-Xa before and after the implementation of the pocket card. The secondary outcomes included a subgroup analysis assessing the effect of the CPAT. Other secondary outcomes were the anti-Xa status (infratherapeutic, therapeutic or supratherapeutic) at 7 and 24 hours of UFH treatment.

RESULTS

We found a significant increase in the time to reach therapeutic dosing with pocket card-guided recommendations implementation (10.1 vs 14 hours, HR of 0.8, 95% CI: 0.70 to 0.93). However, the CPAT was associated with a significant decrease in the time needed to reach the therapeutic range (13.9 vs 7.1 hours, HR of 1.74, 95% CI: 1.17 to 2.60).

CONCLUSION

Although we observed an increase in time to reach therapeutic anti-Xa with the pocket card, possibly due to a selection bias (use of activated partial thromboplastin time for monitoring before the pocket card), the implementation of CPAT significantly decreased the delay for effective therapy. Further studies are needed to confirm these findings, and to determine the optimal initial dose of UFH anticoagulation.

Monitoring unfractionated heparin therapy: Lack of standardization of anti-Xa activity reagents

INTRODUCTION

One of the main advantages of using anti-Xa instead of activated partial thromboplastin time in monitoring of unfractionated heparin (UFH) therapy relies on its hypothesized standardization, with a unique therapeutic range defined to be 0.30 to 0.70 IU/mL. The aim of the present study was to compare the inter-reagent agreement of anti-Xa activity.

METHODS

Citrate tubes were obtained from 104 inpatients on UFH. Plasma samples were stored frozen in aliquots at -70°C before being shipped to three accredited coagulation laboratories to be evaluated for anti-Xa activity using their routine assay(s). Pooled normal plasmas spiked with dilutions of the 6th International Standard of UFH to achieve anti-Xa activities up to 1.0 IU/mL were evaluated using the same techniques.

RESULTS

In the plasmas from patients on UFH, the median anti-Xa activity ranged from 0.37 IU/mL with one reagent to 0.57 IU/mL with another; results were in between (0.45 IU/mL) using two other reagents. Comparisons of results obtained using the different reagents demonstrated unacceptable bias up to 0.24 IU/mL between some reagents (41% difference). The concordance as whether anti-Xa activities measured using different reagents were within or outside the therapeutic range was between 0.411 and 0.939 (kappa). Similar discrepancy was demonstrated for anti-Xa activities when evaluating normal plasma spiked with the International Standard. A discrepancy of the same order of magnitude was demonstrated in the 2017 External Quality Assessment Program provided by the External Quality Control in Assays and Tests exercises.

CONCLUSIONS

The reported discrepancy between test results obtained using different anti-Xa assays clearly suggests a lack of standardization of that assay with potentially significant impact on the patients' anticoagulation.

Aspirin Compared with Anticoagulation to Prevent Venous Thromboembolism After Knee or Hip Arthroplasty: a Large Retrospective Cohort Study

BACKGROUND

Although guidelines now allow the use of aspirin as an alternative to anticoagulants for venous thromboembolism prophylaxis after knee or hip arthroplasty, there is limited data on contemporary use and outcomes with aspirin.

OBJECTIVE

To describe the use of pharmacologic thromboprophylaxis and to assess venous thromboembolic risk with aspirin compared with anticoagulation after knee or hip arthroplasty.

DESIGN

Retrospective cohort study using data from the US MedAssets database.

PATIENTS

Adults with a principal discharge diagnosis of knee or hip arthroplasty between January 1, 2013, and December 31, 2014.

MAIN MEASURES

We identified charges for medications used for thromboprophylaxis within 7 days after the index surgery from billing records. The primary outcome was postoperative venous thromboembolism identified by International Classification of Diseases, 9th edition codes, from the index hospitalization, rehospitalization within 30 days, or during an outpatient visit within 90 days postoperatively. We compared postoperative thromboembolic risk in patients receiving aspirin-only and those receiving anticoagulants using propensity score-adjusted multivariable logistic regression models.

KEY RESULTS

We identified 74,234 patients with knee arthroplasty and 36,192 with hip arthroplasty who received pharmacologic thromboprophylaxis. Aspirin-only was used in 27.9% of all patients, while 24.2% and 24.1% received warfarin or enoxaparin as prophylactic monotherapy, respectively. Postoperative venous thromboembolism occurred in 495 (0.67%) patients undergoing knee arthroplasty and 145 (0.40%) undergoing hip arthroplasty. Aspirin-only was not related to increased odds of postoperative venous thromboembolism compared with anticoagulants in multivariable adjusted analyses (odds ratio [OR] 0.70; 95% confidence interval [CI], 0.56-0.87, and OR 0.93; 95% CI, 0.62-1.38 for knee or hip arthroplasty, respectively).

CONCLUSIONS

More than a fourth of all patients received aspirin as the sole antithrombotic agent after knee or hip arthroplasty. Postoperative thromboprophylaxis with aspirin-only was not associated with a higher risk of postoperative venous thromboembolism compared with anticoagulants after hip or knee arthroplasty.

Comparing Anti-Factor Xa and Activated Partial Thromboplastin Levels for Monitoring Unfractionated Heparin

Background: Lab tests such as activated partial thromboplastin time (aPTT) or anti-factor Xa (anti-Xa) levels are typically used to monitor intravenous unfractionated heparin (IV heparin), with recent evidence suggesting that anti-Xa levels may provide a more accurate measure of anticoagulation. Objective: The Lexington Veterans Affairs Health Care System transitioned from using aPTT to anti-Xa levels in January 2017. This study was conducted to evaluate the efficacy and safety of this change. Methods: This was a retrospective cohort study comparing all patients receiving IV heparin per protocol for at least 24 hours from August 1, 2016, to January 31, 2017 (aPTT group), and February 1, 2017, to July 31, 2017 (anti-Xa group). The primary objective was a comparison of IV heparin doses required to achieve goal range between the 2 cohorts. Secondary objectives included a comparison of time to therapeutic goal, percentage of time within goal range, number of rate changes until therapeutic goal, and adverse outcomes, such as number of bleeds. Results: A total of 155 patients were included in this study. Significantly higher IV heparin doses were required to achieve therapeutic goal in the anti-Xa group, despite significantly fewer IV heparin rate changes required. Anti-Xa monitoring was not associated with an increased risk of adverse events. Conclusion and Relevance: Significantly higher IV heparin doses were required to achieve therapeutic anti-Xa levels after transitioning from an aPTT-based protocol in the largely unstudied veteran population. However, the transition from aPTT to anti-Xa monitoring appears safe and efficacious in these patients.

The Burden of Hypoxic Respiratory Failure in Preterm and Term/Near-term Infants in the United States 2011-2015

OBJECTIVES

This study quantified the burden of hypoxic respiratory failure (HRF)/persistent pulmonary hypertension of newborn (PPHN) in preterm and term/near-term infants (T/NTs) by examining health care resource utilization (HRU) and charges in the United States.

METHODS

Preterms and T/NTs (≤34 and >34 weeks of gestation, respectively) having HRF/PPHN, with/without meconium aspiration in inpatient setting from January 1, 2011-October 31, 2015 were identified from the Vizient database (first hospitalization=index hospitalization). Comorbidities, treatments, HRU, and charges during index hospitalization were evaluated among preterms and T/NTs with HRF/PPHN. Logistic regression was performed to evaluate mortality-related factors.

RESULTS

This retrospective study included 504 preterms and 414 T/NTs with HRF/PPHN. Preterms were more likely to have respiratory distress syndrome, neonatal jaundice, and anemia of prematurity than T/NTs. Preterms had significantly longer inpatient stays (54.1 vs 29.0 days), time in a neonatal intensive care unit (34.1 vs 17.5 days), time on ventilation (4.7 vs 2.2 days), and higher total hospitalization charges ($613 350 vs $422 558) (all P<0.001). Similar rates were observed for use of antibiotics (96.2% vs 95.4%), sildenafil (9.5% vs 8.2%), or inhaled nitric oxide (93.8% vs 94.2%). Preterms had a significantly higher likelihood of mortality than T/NTs (odds ratio: 3.6, 95% confidence interval: 2.3-5.0).

CONCLUSIONS

The findings of more severe comorbidities, higher HRU, hospitalization charges, and mortality in preterms than in T/NTs underscore the significant clinical and economic burden of HRF/PPHN among infants. The results show significant unmet medical need; further research is warranted to determine new treatments and real-world evidence for improved patient outcomes.

Traditional and non-traditional anticoagulation management during extracorporeal membrane oxygenation

Unfractionated heparin (UFH) is the anticoagulant of choice during extracorporeal membrane oxygenation (ECMO) support. Despite its favorable pharmacologic properties, management of heparin anticoagulation during ECMO remains a major challenge. To date, little is known about the optimal monitoring strategy or the heparin dose offering the best safety/efficacy profile. Therefore, it remains unclear if the heparin dose should be adapted to target a specific "clotting time" [e.g., activated clotting time (ACT) or activated partial thromboplastin time (aPTT)] or a heparin concentration, measured by coagulation factor anti-Xa assay. In addition, no study has compared the relevance of modern viscoelastic coagulation tests over the single value of a clotting time or heparin concentration value. Although guidelines for anticoagulation during ECMO support have been published, the absence of evidence limits the quality of the recommendations provided, which explains the major intra- and inter-institutional variability observed. Large prospective multicenter trials are urgently needed to investigate the optimal anticoagulation management strategy during ECMO support.

Comparison of Antifactor Xa and Activated Partial Thromboplastin Time Monitoring for Heparin Dosing in Vascular Surgery Patients: A Single-Center Retrospective Study

BACKGROUND

Vascular surgery patients often require anticoagulation with intravenous unfractionated heparin monitored through antifactor Xa (anti-Xa) levels or the activated partial thromboplastin time (aPTT). This study compares the 2 monitoring strategies in terms of major bleeding events in the vascular surgery population.

METHODS

This was a single-center, retrospective study that included patients treated with a pharmacy-managed heparin protocol monitored by either anti-Xa or aPTT after vascular surgery. The primary outcome was the percentage of patients experiencing major bleeding events after procedure. Secondary outcomes evaluated minor bleeding episodes, postprocedure packed red blood cell transfusions, and the incidence of thrombotic events. In a secondary analysis, simultaneously measured anti-Xa and aPTT values were identified and analyzed for discordance.

RESULTS

Major bleeding occurred in 12/72 patients (17%) on the anti-Xa-monitored protocol versus 5/62 patients (8%) on the aPTT-monitored protocol (P = 0.19). Minor bleeding episodes were documented in 10% of the patients in the anti-Xa group versus 6% in the aPTT group (P = 0.54). There were no significant differences between the 2 groups in packed red blood cell transfusions and thrombotic events. Of 109 pairs of simultaneously measured anti-Xa and aPTT values, 39 pairs (36%) showed relatively high aPTT values compared with corresponding anti-Xa levels. Nine patients who had these discordant test results experienced bleeding while their heparin drip was titrated based on lower anti-Xa values.

CONCLUSIONS

The use of anti-Xa levels for heparin titration showed higher rates of major bleeding complications in vascular surgery patients compared with aPTT monitoring, but no significant difference was identified in this study. Vascular surgery patients with relatively high aPTT to anti-Xa values may have an increased risk of bleeding complications when heparin is titrated based on anti-Xa levels.