key: cord-0778894-c6f5wqlr
authors: Soni, Mamta; Gopalakrishnan, Ram
title: Significance of RDW in predicting mortality in COVID‐19—An analysis of 622 cases
date: 2021-03-27
journal: Int J Lab Hematol
DOI: 10.1111/ijlh.13526
sha: 9a72d7b5df753e7500789f76b610aa8e6f0dc27c
doc_id: 778894
cord_uid: c6f5wqlr

nan

There is significant evidence to suggest that inflammatory responses play a critical role in COVID-19. 2 A possible association can exist between a high RDW and inflammation. 3 Inflammatory responses negatively impact RBC production and turnover. 3, 4 Many of the pro-inflammatory cytokines up-regulated in COVID-19 such as tumor necrosis factorα and interleukin-1 can cause reduction in erythropoietin production. 2 Further, SARS-CoV-2 infection can cause both direct injury to the peripheral circulating RBCs or erythroblasts in bone marrow and an indirect injury to RBCs due to hemolytic anemia or intravascular coagulopathy, and disturbances in iron metabolism. [5] [6] [7] Overall, the predominant cause of elevation of RDW in COVID-19 is indicated to be the increased number of older RBCs in the circulation due to delayed clearance. 1,3 This is because older RBCs have a reduced volume resulting in a reduced MCV.

RDW is a useful predictor of the clinical outcomes in critically ill patients and in patients with infection and sepsis. 4,8 RDW may provide information for early risk stratification of COVID-19 patients and enable timely interventions to reduce mortality and morbidity.

Although certain markers such as D-dimer and eosinophils have been evaluated as prognostic indicators in COVID-19 infection, 9, 10 only a few studies have explored the role of RDW in predicting prognosis. In a pandemic, early risk stratification based on a biomarker, which is routinely available with existing tests, without any extra cost can help efficient utilization of both critical care and laboratory resources, particularly in resource-constrained environments. Thus, we aimed to evaluate the role of RDW as a prognostic indicator in COVID-19-infected patients.

For our study, data on patient demography, laboratory investigations, and clinical details of confirmed COVID-19 cases admitted between June 04, 2020, and September 11, 2020, at Apollo Hospitals, Chennai, India, were retrieved through electronic records and analyzed.

As per World Health Organization guidelines, patients with a positive result of the nucleic acid test for SARS-CoV-2 by RT-PCR were considered as confirmed COVID-19 cases. Adult patients (≥18 years) who had a definite outcome (discharge or death) during the course of admission were included in the study. Patients still under admission were excluded from the study.

The complete blood count was performed on fully automated hematology analysers (Coulter DXH 900 and Siemens Healthineers ADVIA 2120i). Reference interval for RDW-CV at our center is 11.6%-14.5%. Any value above 14.5% was considered as elevated.

The data were analyzed for a total of 772 patients, of which 150 negative samples were kept as reference for normal distribution. Cox proportional hazards regression model showed that RDW > 14.5% was an independent predictor of mortality, beyond age, gender, D-dimer level, and comorbidities (Table 2) . Table 3) .

Comparison of the mean RDW at admission and before discharge or death showed an increase (P < .01) in both survivors and nonsurvivors. However, the mean increase in RDW in the nonsurvivors group was nearly 4 times than that in the survivors group (1.2 and 0.31, respectively).

In this study, we also attempted to establish a cutoff value of RDW for predicting mortality in COVID-19 patients. The optimum cutoff value for RDW for predicting mortality calculated by using the ROC curve was 14.90%, with a sensitivity of 77.32% and a specificity of 65.0%. C-index was 0.738.

The results of our study are similar to other evaluations of the association of elevated RDW with mortality. In a cohort study that included 1641 patients with COVID-19, RDW was associated with increased mortality risk in Cox proportional hazards modeling adjusted for various parameters including age and D-dimer (HR of 2.01 for an RDW >14.5% versus ≤14.5%). 3 Similar to the finding in our study, an increase in RDW over the period of hospitalization was associated with increased mortality. 3 In another study of 294 hospitalized COVID-19 patients, RDW was associated with increased mortality (Odds Ratio = 4.5; 95% CI 1.4-14.3) after adjustment for covariates such as age, anemia, and co-morbidities. 11 However, in one smaller study that included 70 COVID-19 patients, although RDW was found to be higher, there was no significant association with mortality. 12 

Our study has some limitations. As ours was a single-center, retrospective study, it could have resulted in a selection bias. A larger, multicentric study may be required to confirm the findings. As there was no follow-up, post-discharge clinical status could not be ascertained. It is acknowledged that a prediction model for outcomes in COVID-19 patients will include a combination of clinical and laboratory parameters.

In conclusion, RDW can be considered during the workup for COVID-19 patients as it helps in early risk stratification for efficient and effective utilization of available resources especially in limited resources settings.

There are no funding sources to declare.

The author has no competing interests.

The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions. 

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Red blood cell distribution width (RDW) predicts COVID-19 severity: a prospective, observational study from the Cincinnati SARS-CoV-2 emergency department cohort

Autoimmune haemolytic anaemia associated with COVID-19 infection

Evidence of structural protein damage and membrane lipid remodeling in red blood cells from COVID-19 patients

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D-dimer level is a useful predictor for mortality in patients with COVID-19: analysis of 483 cases

Evaluation of eosinopenia as a diagnostic and prognostic indicator in COVID-19 infection

Red blood cell distribution width (RDW) in Hospitalized COVID-19 Patients

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