RDW : useful prognostic marker in acute COVID -19 infection

ABSTRACT

COVID-19 is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which has been associated with over 5 million deaths worldwide since December 2019. Red cell distribution width (RDW) is a routine full blood count parameter that reflects the level of change in size between red cells (anisocytosis) and has been widely researched as an independent predictor of mortality in different hospital settings, including critically ill patients with sepsis. This study aims to investigate if RDW results on admission may be used as a prognostic marker in patients with acute COVID-19 infection. This retrospective study included 81 hospitalised patients with COVID-19 at the General Hospital in Jersey (Channel Islands, UK), subject to inclusion criteria. Differences between groups were calculated using the t test if data were normally distributed, otherwise the Mann-Whitney test was used. p < 0.05 was considered significant for all tests. Area under curve (AUC) and the 95% confidence interval (CI) were determined to establish optimal cut-off point that maximised sensitivity and specificity to predict death by the Youden's index. Logistic regression was then used to determine the odds of in-hospital mortality. Non-survivors were found to be significantly older (median age 82 years;overall range 50-94 vs. 74 years;overall range 28-92 in survivors;p = 0.003) and presented with higher RDW when compared with survivors (14.1 vs. 13.4;p = 0.028). A total of 63 patients (78%) received ward-based care, while 18 patients (22%) required intensive care. Men accounted for most deaths (males 16 deaths, 59.3% vs. females 11 deaths, 40.7%), although the mortality rate in males and females was undistinguishable (males 33.3% vs. females 33.3%). Multivariate logistic analysis demonstrated that RDW >14% on admission was associated with a 5-fold increased mortality risk in hospitalised patients with COVID-19 (OR = 5.335 [95% CI 1.524-18.674];p = 0.009). This association was shown to be independent of age and other potential confounders such as lymphocyte count, white cells, or creatinine levels. This study confirms the prognostic potential of RDW in hospitalised patients with COVID-19. Identifying patients with higher risk of in-hospital mortality may enable prioritisation of resources and targeted treatments, which could ultimately improve outcomes.