Hematological Findings and Clinical Severity in Pediatric Patients with COVID-19

To the Editor,

We would like to share some ideas on “Can Hematological Findings of COVID-19 in Pediatric Patients Guide Physicians Regarding Clinical Severity?” [1]. Arıkan et al. [1] concluded that the “neutrophil-to-lymphocyte ratio (NLR) was higher in severe/critical cases… Red cell distribution width (RDW) statistically significantly increased in severe cases”. We agree that basic hematological parameters might be good indicators for monitoring the severity of many medical problems. Regarding coronavirus disease-19 (COVID-19), NLR and RDW might or might not be useful as predictive parameters for severity in children with COVID-19. RDW might not be useful in many settings. In our setting in Southeast Asia, there is a very high incidence of thalassemia. There are also many pediatric cases of COVID-19. Since these children usually have high RDW as a background hematological finding [2], RDW is not useful for the prediction of COVID-19 severity in these cases. Therefore, RDW is not a useful predictive parameter in any setting with a high incidence of thalassemia. The NLR ratio might be a better predictive parameter. However, it is necessary to set a population-specific reference value for clinical application [3].

We thank the author for their interest in our manuscript, and we acknowledge their concerns regarding  use of red cell distribution width (RDW)  in clinical diagnosis of  severity  of COVID-19 infected children in places with very high incidence of thalassemia like  Indochina. While we agree that pediatric children usually have a high RDW as a background hematological disease, in our study none of the patients had thalassemia as underlying disease. And published studies support usage  hematological  parameters including RDW in COVID-19 infected cases.

In a published study, a progressive increase of RDW was observed with advancing COVID-19 severity. Also in multivariate analysis, elevated RDW was associated with 9-fold increased odds of severe COVID-19 [1].

In an other published study, RDW was found to be a prognostic predictor for patients with severe COVID-19, and  authors concluded that the increase in reticulocyte  may contribute to elevated RDW [2].In a study conducted in 1641 patients, authors concluded that elevated RDW at the time of hospital admission and an increase in RDW during hospitalization were associated with increased mortality risk for patients with COVID-19 [3].

In our findings, the NLR ratio was higher in severe/critical cases compared to cases of asymptomatic, mild, and moderate severity. In a study  conducted in 245 COVID-19 patients multivariate analysis demonstrated that there was 8% higher risk of in-hospital mortality for each unit increase in NLR (odds ratio [OR] =1.08; 95% confidence interval [95% CI], 1.01 to 1.14; P=0.0147) [4].

Finally  we conclude  that hematological parameters of COVID-19 infected pediatric cases may alert physicians about clinical severity. But hematological markers especially RDW should be used correctly as patient-based approach in COVID-19 infected pediatric patients.

Kamile Ötiken Arıkan, Şahika Şahinkaya, Elif Böncüoğlu, Elif Kıymet, Ela Cem, Aybüke Akaslan Kara, Nuri Bayram, İlker Devrim