Abstract
The identification of biomarkers predicting disease severity and outcomes is the focus of intense research in patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2 infection). Ideally, such biomarkers should be easily derivable from routine tests. We conducted a systematic review and meta-analysis of the predictive role of the red blood cell distribution width (RDW), a routine hematological test, in patients with SARS-CoV-2 infection. We searched the electronic databases PubMed, Web of Science and Scopus, from January 2020 to November 2020, for studies reporting data on the RDW and coronavirus disease 2019 (COVID-19) severity, defined as severe illness or admission to the intensive care unit (ICU), and mortality. Eleven studies in 4901 COVID-19 patients were selected for the meta-analysis. Pooled results showed that the RDW values were significantly higher in patients with severe disease and non-survivors (standard mean difference, SMD = 0.56, 95% CI 0.31 to 0.81, p < 0.001). Heterogeneity between studies was extreme (I2 = 80.6%; p < 0.001). In sensitivity analysis, the effect size was not modified when each study was in turn removed (effect size range, between 0.47 and 0.63). The Begg’s (p = 0.53) and Egger’s tests (p = 0.52) showed no evidence of publication bias. No significant correlations were observed between SMD and age, gender, whole blood count, end point, study geographic area, or design. Our meta-analysis showed that higher RDW values are significantly associated with COVID-19 severity and mortality. This routine parameter might assist with early risk stratification in patients with SARS-CoV-2 infection.
Highlights
Coronavirus disease 2019 (COVID-19) is a condition caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the agent responsible for the ongoing global pandemic
There is good evidence that severe COVID-19 is associated with significant alterations of routine hematological parameters, an increased neutrophil to lymphocyte ratio, thrombocytopaenia, a prolonged pro-thrombin time, and high D-dimer concentrations [8,9]
To explore the possible contributors to the between-study variance, we investigated the effects of age, gender, publication geographic area, end points, study design and the inflammation biomarker white blood cell (WBC) count on the Standardized mean differences (SMD) by univariate meta-regression analysis
Summary
Coronavirus disease 2019 (COVID-19) is a condition caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the agent responsible for the ongoing global pandemic. The identification of early markers of disease severity would greatly facilitate the selection of COVID-19 patients requiring more aggressive monitoring and management and the judicious use of healthcare resources. Such markers should be relatively inexpensive and easy to derive, for example from routine tests conducted in this group on admission and throughout the hospitalization. Elevations of the RDW can be secondary to a reduced clearance of older red blood cells in the spleen and liver and/or a reduced red blood cell production in the bone marrow The latter has been proposed to occur in the setting of a concomitant increased leukocyte and/or platelet production in pro-inflammatory states [10]. Given that the RDW has been shown to have a good predictive capacity toward adverse clinical outcomes in several acute and chronic disease states [13,14,15,16,17,18,19,20], we conducted a systematic review and meta-analysis of the available evidence on the association between the RDW and measures of disease severity and survival status in patients with
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