Red Cell Distribution Width and Platelet Volume Indices in Critically III Patients
Authors: Joyson Sunil , Kiran H. S. 
Published: June 2024

Background:
Red cell distribution width (RDW) is the quantitative assessment of variation of the size of circulating red blood cells. Platelet volume indices include mean platelet volume (MPV) and platelet distribution width (PDW). Few studies have evaluated RDW and platelet volume indices in critically ill patients. The objective of this study was to assess RDW and platelet volume indices in critically ill patients.

Methods:
It was a prospective observational study. The study included 260 critically ill patients (irrespective of diagnosis) admitted in intensive care units (ICUs) under the department of general medicine, fulfilling inclusion and exclusion criteria. RDW and platelet volume indices within the first 24 h of admission into the hospital were taken. The critically ill patients admitted to ICUs were classified into two groups based on their Acute Physiology And Chronic Health Evaluation II (APACHE II) score on the day of admission (≥18 and <18) and they were compared with 130 noncritically patients admitted in wards.

Results:
The RDW values of critically ill patients with APACHE II score ≥18 was significantly higher (with P value 0.05) when compared to those with APACHE II score <18. The RDW values of critically ill patients with APACHE II score ≥18 was significantly higher (with P = 0.0001) when compared to noncritically ill patients in the wards. The RDW values of critically ill patients with APACHE II score <18 was not significantly higher (with P = 0.111) when compared to noncritically ill patients in the wards. The MPV values of critically ill patients with APACHE II score ≥18 was significantly higher (with P = 0.04) when compared to noncritically ill patients in the wards. The MPV values of critically ill patients with APACHE II score ≥18 was not significantly higher (with “P” = 0.58) when compared to those with APACHE II score <18. The MPV values of critically ill patients with APACHE II score <18 was not significantly higher (with P = 0.73) when compared to noncritically ill patients in the wards. The PDW values of critically ill patients with APACHE II score ≥18 was significantly higher (with P = 0.03) when compared to noncritically ill patients in the wards. The PDW values of critically ill patients with APACHE II score ≥18 was not significantly higher (with P = 1.00) when compared to those with APACHE II score <18. The PDW values of critically ill patients with APACHE II score <18 was not significantly higher (with P = 0.22) when compared to noncritically ill patients in the wards. The RDW, MPV, and PDW correlate with the severity of critical illness but not with mortality. RDW and platelet volume indices do not vary between males and females. RDW and platelet volume indices do not vary among various age groups.

Conclusion:
RDW and platelet volume indices of critically ill patients admitted to ICUs were more when compared with noncritically ill patients. Hence, RDW and platelet volume indices can be considered as indicators of the severity of critical illnesses and could be used in day-to-day practice as markers of severity of critical illness. Among these three indices (RDW, MPV, PDW), RDW appears to be the best with respect to the association with the severity of critical illness. However, RDW and platelet volume indices are not good tools for the prediction of mortality in critically ill patients.