To the Editor:We read with great interest the article by Tacquard et al1Tacquard C. Mansour A. Godon A. et al.Impact of high dose prophylactic anticoagulation in critically ill patients with COVID-19 pneumonia. published in CHEST (June 2021). Authors showed that high-dose prophylactic anticoagulation therapy is associated with reduced thrombotic complications in critically ill patients with COVID-19 without increasing bleeding risk. We want to raise a few points that may be important for authors and readers of the article.This is a retrospective multi-hospital study that compared thrombotic complications in patients treated with high-dose prophylactic anticoagulation (HPAC) to usual dose prophylactic anticoagulation (UPAC). The study started on March 21, 2020, and ended April 10, 2020, which is a noticeably short time. The study compares the practice of anticoagulation before and after guidelines [French Working Group on Perioperative Hemostasis] published on April 3, 2020. We believe the study may have overestimated thrombotic complications in the UPAC group and underestimated bleeding complications in the HPAC group. Patients treated with UPAC may have received higher number of CT chest scans for suspicion of pulmonary embolism than patients with HPAC. Clinicians using HPAC are less likely to consider CT chest scans for a diagnosis of pulmonary embolism because the patient was already on HPAC. The authors may clarify this issue by reporting the number of CT scans performed for both groups. The practice of anticoagulation is highly variable and dynamic. We documented this practice and this practice’s impact on clinical outcome.2Nadeem R. Thomas S.J. Fathima Z. et al.Pattern of anticoagulation prescription for patients with Covid-19 acute respiratory distress syndrome admitted to ICU. Tacquard et al1Tacquard C. Mansour A. Godon A. et al.Impact of high dose prophylactic anticoagulation in critically ill patients with COVID-19 pneumonia. divided data into five time points and captured only the first or last timeframe to define groups (UPAC or HPAC). They did not include data from the middle timeframes in their study, which might have affected results. Moreover, cumulative doses would likely be higher for the UPAC group because they started earlier, while cumulative doses for HPAC would be lower because they started later. Therefore, thrombotic complications may not be accurate and possibly overestimated in UPAC group.

Bleeding complications may have been under estimated because the follow-up time to detect bleeding complications was truly short; for 38% of the sample, bleeding complications dates were not available. The number and nature of bleeding complications, if available, can improve our understanding of the issue.

In fact, high thrombotic complications in the UPAC group in their study may be a result of higher severity of illness, prolonged mechanical ventilation (extended use of sedatives and muscular paralytics), higher usage of continuous renal replacement therapy, and extracorporeal membrane oxygenation. Adjustment for all confounding factors by appropriate statistical modeling would allow a true estimate of thrombotic complications.

Global improvement in the provision of ICU beds, ventilators, and society guidelines occurred at approximately the last week of March 2020. Subsequently patients might have received better care in terms of location and trained staff. This could improve the occurrence of thrombotic complications in the HPAC group. We have observed that continuous renal replacement therapy circuits clot more often when care is provided outside the ICU by staff who are not trained for critical care.

ReferencesTacquard C. Mansour A. Godon A. et al.

Impact of high dose prophylactic anticoagulation in critically ill patients with COVID-19 pneumonia.

Chest. 159: 2417-2427Nadeem R. Thomas S.J. Fathima Z. et al.

Pattern of anticoagulation prescription for patients with Covid-19 acute respiratory distress syndrome admitted to ICU.

Does it impact outcome? Heart Lung. 50: 1-5Article InfoFootnotes

FINANCIAL/NONFINANCIAL DISCLOSURES: None declared.

Identification

DOI: https://doi.org/10.1016/j.chest.2021.02.036

Copyright

© 2021 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.

ScienceDirectAccess this article on ScienceDirect Linked ArticleRelated Articles