RBC Distribution Width: Biomarker for Red Cell Dysfunction and Critical Illness Outcome?
RBC distribution width is reported to be an independent predictor of outcome in adults with a variety of conditions. We sought to determine if RBC distribution width is associated with morbidity or mortality in critically ill children.



Retrospective observational study.



Tertiary PICU.



All admissions to St. Louis Children's Hospital PICU between January 1, 2005, and December 31, 2012.



We collected demographics, laboratory values, hospitalization characteristics, and outcomes. We calculated the relative change in RBC distribution width from admission RBC distribution width to the highest RBC distribution width during the first 7 days of hospitalization. Our primary outcome was ICU mortality or use of extracorporeal membrane oxygenation as a composite. Secondary outcomes were ICU- and ventilator-free days.



We identified 3,913 eligible subjects with an estimated mortality (by Pediatric Index of Mortality 2) of 2.94% ± 9.25% and an actual ICU mortality of 2.91%. For the study cohort, admission RBC distribution width was 14.12% ± 1.89% and relative change in RBC distribution width was 2.63% ± 6.23%. On univariate analysis, both admission RBC distribution width and relative change in RBC distribution width correlated with mortality or the use of extracorporeal membrane oxygenation (odds ratio, 1.19 [95% CI, 1.12-1.27] and odds ratio, 1.06 [95% CI, 1.04-1.08], respectively; p < 0.001). After adjusting for confounding variables, including severity of illness, both admission RBC distribution width (odds ratio, 1.13; 95% CI, 1.03-1.24) and relative change in RBC distribution width (odds ratio, 1.04; 95% CI, 1.01-1.07) remained independently associated with ICU mortality or the use of extracorporeal membrane oxygenation. Admission RBC distribution width and relative change in RBC distribution width both weakly correlated with fewer ICU- (r = 0.038) and ventilator-free days (r = 0.05) (p < 0.001).



Independent of illness severity in critically ill children, admission RBC distribution width is associated with ICU mortality and morbidity. These data suggest that RBC distribution width may be a biomarker for RBC injury that is of sufficient magnitude to influence critical illness outcome, possibly via oxygen delivery impairment.
1Department of Pediatrics, Washington University in St. Louis, St. Louis, MO. 2Department of Pathology and Immunology, Washington University in St. Louis, St. Louis, MO. 3Department of Biostatistics, Washington University in St. Louis, St. Louis, MO. 4Department of Biochemistry & Molecular Biophysics, Washington University in St. Louis, St. Louis, MO. 5Department of Pediatrics, University of Utah, Salt Lake City, UT.
Ahmed S
AS
Said
Philip C
PC
Spinella
Mary E
ME
Hartman
Katherine M
KM
Steffen
Ronald
R
Jackups
Richard
R
Holubkov
Mike
M
Wallendorf
Allan
A
Doctor
D000293:Adolescent; D015415:Biomarkers / Q000097:blood; D002648:Child; D002675:Child, Preschool; D003422:Critical Care; D016638:Critical Illness / Q000401:mortality* / Q000628:therapy; D004909:Erythrocyte Indices; D004912:Erythrocytes / Q000473:pathology* / Q000502:physiology; D015199:Extracorporeal Membrane Oxygenation; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D015278:Intensive Care Units, Pediatric; D016014:Linear Models; D016015:Logistic Models; D008297:Male; D011379:Prognosis; D012372:ROC Curve; D012189:Retrospective Studies; D012720:Severity of Illness Index
D015415:Biomarkers