key: cord-0943595-wcqb3y29
authors: Zhang, Litao; Yan, Xinsheng; Gong, Yiyao; Zhang, Zhenlu
title: Response to ‘the association between D‐dimer in COVID‐19 patients and mortality remains beset of uncertainties’
date: 2020-06-30
journal: J Thromb Haemost
DOI: 10.1111/jth.14979
sha: ba538dd5cec5d66d5520f274b6ddd036868864a9
doc_id: 943595
cord_uid: wcqb3y29

We appreciate the opportunity to respond Dr. Gris and colleagues who still have doubts about the predictive of D‐dimer in COVID‐19[1, 2]. We totally understand the concerns from Dr. Gris and colleagues who just want to manage their patients better. We are trying to explain the potential influence factors here, hope to provide any useful information for managing the COVID‐19 patients.

We appreciate the opportunity to respond Dr. Gris and colleagues who still have doubts about the predictive of D-dimer in COVID-19 [1, 2] . We totally understand the concerns from Dr. Gris and colleagues who just want to manage their patients better. We are trying to explain the potential influence factors here, hope to provide any useful information for managing the COVID-19 patients.

The mortalities differed greatly among studies, hospitals, or even countries. Up to June 8 2020, the overall mortality of COVID-19 in China was 5.5% (4638/84191) [3] , which was 6.6%

for Hubei (containing Wuhan, 4512/68135), China [3] . During the outbreak, our hospital was designated to admit the laboratory-confirmed COVID-19 patients who were moderate type (84.0%, 288/343), severe type (11.7%, 40/343) or critical severe type (4.4%, 15/343) according to the Chinese clinical guidance for COVID-19 pneumonia diagnosis and treatment [4] . Besides, those mild cases who had no or just have mild clinical symptoms, and no sign of pneumonia on chest imaging were mainly admitted to mobile cabin hospital [5] . As a whole, the distribution of patients existing in our study was basically consistent with the epidemiological characteristics of COVID-19 in Hubei, China. Thus, due to small sample sizes (191 cases, 99 cases respectively) of the two retrospective studies [6, 7] , the mortalities from the two studies should be unrepresentative, and comparison of the mortalities might be inappropriate. could be roughly inferred that the study populations were significantly different between the two studies. It is certain that the severe/critical cases suffered much higher mortalities compared to those mild or moderate cases. Thus, these might contribute to the difference of mortalities.

Another unignorable point we have mentioned in limitation was the difference of length from symptom onset to admission[8]. Due to differences in patient number and medical resources in different areas, the lengths from illness onset to admission might be hugely varying. For example, the median of length from illness onset to admission in our study was 10 days (IQR: 7-15 days), which might also contribute to the difference between the data from Dr. Gris and ours. This was why we suggested that dynamic measurement of D-dimer to provide more information.

This article is protected by copyright. All rights reserved Actually, when we first analyzed the data, we were surprised by the striking difference of mortalities between two group (12 deaths vs. 1 deaths), too. Then we cross-checked the original data for several times and it was true. There were unexpectedly no significant difference observed in Dr. Gris's data (8/77 vs 17/93) [2] , which might be attributed to the above reasons. Furthermore, because of the limited data Dr. Gris et al. provided, we also do not know whether there were differences in the baseline characteristics. In this case, it would be better to establish a suitable cutoff value and evaluate the predictive value of D-dimer in COVID-19 based on their own population.

The potential use of D-dimer in COVID-19 based on recent evidences has been simply summarized in our previous response. There are still many uncertainties and potential uses of D-dimer in COVID-19, such as whether it can be used to guide anticoagulation adjustment, initiating mechanical ventilation, de-escalating critical care support [9] , which are worthwhile to expect the further studies to describe more details.

Uncertainties on the prognostic value of D-dimers in COVID-19 patients

The association between D-dimers in COVID-19 patients and mortality remains beset of uncertainties

The novel coronavirus (2019-nCoV) global

China National Health Commission of the People's Republic of. Chinese Clinical Guidance for COVID-19 Pneumonia Diagnosis and Treatment

Clinical Characteristics and Outcomes of 421 Patients With

Treated in a Mobile Cabin Hospital

Clinical course and risk factors for mortality of adult inpatients with COVID-19 in Wuhan, China: a retrospective cohort study

Epidemiological and clinical characteristics of 99 cases of

China: a descriptive study