What Do We Know about Thromboprophylaxis and Its Monitoring in Critically Ill Patients?

Monitoring anti-Xa Levels to Optimize Low-Molecular-Weight-Heparin Thromboprophylaxis in High-Risk Hospitalized Patients: A Stratified Meta-Analysis

It is uncertain whether monitoring or targeting anti-Xa levels is necessary when using low-molecular-weight-heparin (LMWH) to prevent venous thromboembolism (VTE). This stratified meta-analysis assessed whether monitoring trough or peak anti-Xa levels with LMWH dosing would reduce risk of VTE. Twelve non-randomized studies involving 3604 hospitalized patients met the inclusion criteria and were subject to meta-analysis. Eight studies assessed the association between VTE and peak anti-Xa levels (between .2 and .5 IU/ml) and four studies assessed the benefits of targeting the trough anti-Xa levels (>.1 IU/ml). Achieving an adequate peak or trough anti-Xa level was associated with a reduced risk of VTE (random-effects model odds ratio [OR] .52, 95% confidence interval [CI] .34-.77; P = .001, I2 = 30% and P-value for heterogeneity = .171) compared with using a fixed standard dose of LMWH. Targeting the trough level (OR .40, 95%CI 0.22-.75, P = .004) appeared to be more effective than targeting the peak level (OR .62, 95%CI 0.37-1.03, P = .066), although a formal interaction analysis did not confirm they were statistically different (ratio of ORs = 1.52, 95%CI 0.68-3.40; z score = 1.03, P = .306). Targeting a higher anti-Xa level did not appear to increase the risk of bleeding or transfusion (OR 1.20, 95%CI 0.46-3.17, P = .707).

Anti-factor Xa level monitoring of low-molecular-weight heparin for prevention of venous thromboembolism in critically ill patients (AXaLPE): protocol of a randomised, open-label controlled clinical trial

INTRODUCTION

Whether and when to monitor the amount of anti-factor Xa (aFXa) activity in critically ill patients with complex diseases to prevent venous thromboembolism (VTE) remain unclear. This study is a randomised controlled trial to investigate the effect of aFXa level monitoring on reducing VTE and to establish a new method for accurately preventing VTE in critically ill patients with low-molecular-weight heparin (LMWH).

METHODS AND ANALYSIS

A randomised controlled trial is planned in two centres with a planned sample size of 858 participants. Participants will be randomly assigned to three groups receiving LMWH prophylaxis at a 1:1:1 ratio: in group A, peak aFXa levels will serve as the guide for the LMWH dose; in group B, the trough aFXa levels will serve as the guide for the LMWH dose; and in group C, participants serving as the control group will receive a fixed dose of LMWH. The peak and trough aFXa levels will be monitored after LMWH (enoxaparin, 40 mg, once daily) reaches a steady state for at least 3 days. The monitoring range for group A's aFXa peak value will be 0.3-0.5 IU/mL, between 0.1 and 0.2 IU/mL is the target range for group B's aFXa trough value. In order to reach the peak or trough aFXa levels, groups A and B will be modified in accordance with the monitoring peak and trough aFXa level. The incidence of VTE will serve as the study's primary outcome indicator. An analysis using the intention-to-treat and per-protocol criterion will serve as the main outcome measurement.

ETHICS AND DISSEMINATION

The Xuanwu Hospital Ethics Committee of Capital Medical University and Peking University First Hospital Ethics Committee have approved this investigation. It will be released in all available worldwide, open-access, peer-reviewed publications.

TRIAL REGISTRATION NUMBER

NCT05382481.

Adjusted versus fixed doses of LMWHs in trauma patients: A systematic review and meta-analysis

PURPOSE

Venous thromboembolism (VTE) causes significant morbidity and mortality in patients with traumatic injuries, despite thromboprophylaxis. To decrease both thrombotic and bleeding risks, some authors suggest adjusting the thromboprophylactic doses of low-molecular-weight heparins (LMWH), in particular according to body weight at treatment initiation or to changes in anti-factor Xa level during treatment. Our objective was to estimate in trauma patients the efficacy and safety of such adjustments, compared with the conventional strategy of fixed-dose LMWH thromboprophylaxis.

SOURCE

A systematic review and a meta-analysis were conducted to identify and assess randomised control trials and observational studies with prospective enrolment that included trauma patients and compared adjustment of LMWH thromboprophylaxis versus no adjustment. The primary and secondary endpoints were VTE and bleeding, respectively. The Odds Ratio (OR) and 95% Confidence Interval (95% CI) were calculated using the Mantel-Haenszel method.

PRINCIPAL FINDINGS

Nine studies were included in the meta-analysis. No significant reduction in the risk of VTE was observed with adjusted doses of LMWH compared with fixed doses when considering only randomised control trials (OR 1.02 [95% CI, 0.09 to 11.6]) or all trials (OR 0.70 [95% CI, 0.34 to 1.42]). Similarly, there was no significant difference in bleeding risk (OR 1.36, 95% CI 0.59 to 3.10).

CONCLUSION

This meta-analysis shows that, to date, there is no evidence to justify adjusting LMWH doses, in agreement with the recommendations of the American College of Chest Physicians.

Challenging management dogma where evidence is non-existent, weak or outdated

Medical practice is dogged by dogma. A conclusive evidence base is lacking for many aspects of patient management. Clinicians, therefore, rely upon engrained treatment strategies as the dogma seems to work, or at least is assumed to do so. Evidence is often distorted, overlooked or misapplied in the re-telling. However, it is incorporated as fact in textbooks, policies, guidelines and protocols with resource and medicolegal implications. We provide here four examples of medical dogma that underline the above points: loop diuretic treatment for acute heart failure; the effectiveness of heparin thromboprophylaxis; the rate of sodium correction for hyponatraemia; and the mantra of "each hour counts" for treating meningitis. It is notable that the underpinning evidence is largely unsupportive of these doctrines. We do not necessarily advocate change, but rather encourage critical reflection on current practices and the need for prospective studies.

Mortality of Patients Infected by COVID-19 with and without Deep-Vein Thrombosis

Background: Current evidence points to a state of hypercoagulability (consequence of hyperinflammation) as an important pathogenic mechanism that contributes to the increase in mortality in cases of COVID-19. The aim of the present study was to investigate the influence of deep-vein thrombosis on mortality patient’s infected with SARS-CoV-2. Method: A clinical trial was conducted involving 200 consecutive patients with COVID-19—100 patients who were positive for deep-vein thrombosis (venous Doppler ultrasound) and 100 who were negative for deep-vein thrombosis at a public hospital. Results: The mortality rate was 67% in the group positive for DVT and 31% in the group negative for DVT. Conclusion: Deep-vein thrombosis is associated with an increase in mortality in patients with COVID-19 and failures can occur with conventional prophylaxis for deep-vein thrombosis.