Red cell distribution width as a novel predictor of mortality in ICU patients

Figures & data

Figure 1. Comparisons of Acute Physiology and Chronic Health Evaluation (APACHE) II score (A), ICU mortality rate (B) and the total length of stay in the hospital (TLSH) (C) among patients with different red blood cell distribution width (RDW) tertiles.

Table I. Base-line clinical and laboratory characteristics by tertile of RDW.

	Tertile I	Tertile II	Tertile III	P
RDW (%)	12.9 ± 0.4	14.0 ± 0.4	16.6 ± 2.2	<0.001
	(11.2–13.4)	(13.5–14.6)	(14.7–26.9)
n	205	202	195	–
Male (%)	58.5	57.9	58.0	1.000
Age (years)	61.8 ± 19.3	73.7 ± 13.0	76.0 ± 13.4	<0.001
Principal diagnosis leading to ICU admission (%)
ICU admission (%)
Pulmonary disease	25.3	29.7	37.9	0.022
Cardiovascular disease	36.1	39.6	30.3	0.145
Neurological disease	10.2	8.9	4.1	0.056
Digestive disease	8.3	4.0	5.6	0.178
Infectious disease/sepsis	2.4	5.9	7.7	0.057
Renal insufficiency	1.0	2.5	4.1	0.141
Poisoning	8.3	4.5	2.1	0.015
Trauma	2.9	1.0	1.5	0.323
Other	5.4	4.0	6.7	0.485
Accompanying infection (%)	32.2%	46.0%	56.4%	<0.001
Hemoglobin (g/L)	124.9 ± 19.5	119.0 ± 23.9	109.5 ± 25.8	<0.001
MCV (μm^3)	92.9 ± 4.3	92.6 ± 5.1	92.0 ± 9.5	1.000
APACHE-II score (points)	10.7 ± 6.5	13.3 ± 6.2	15.8 ± 7.2	<0.001
eGFR (mL/min/1.73 m^2)	85.3 ± 42.5	70.5 ± 42.8	60.3 ± 41.8	<0.001
Albumin (g/L)	35.1 ± 4.8	34.0 ± 4.5	31.7 ± 5.1	<0.001
CRP (mg/L)	55.7 ± 57.3	59.7 ± 57.4	69.5 ± 61.6	0.027

APACHE-II score = Acute Physiology and Chronic Health Evaluation II score; CRP = C-reactive protein; eGFR = estimated glomerular filtration rate; MCV = mean corpuscular volume; RDW = red cell distribution width.

Figure 2. ROC curve for Acute Physiology and Chronic Health Evaluation (APACHE) II score, red blood cell distribution width (RDW) and combination of both in predicting ICU mortality.

Figure 3. Odds ratio for ICU mortality by logistic regression analysis in four groups. Red blood cell distribution width (RDW) as an additive marker with Acute Physiology and Chronic Health Evaluation (APACHE) II score for predicting ICU mortality.

Table II. Univariate odds ratios of variables for predicting ICU mortality.

Variables	Odds ratio	95% CI	P
Male	1.007	0.677–1.497	0.974
Age (years)	1.796	1.382–2.337	<0.001
RDW (%)	1.784	1.475–2.158	<0.001
Hemoglobin (g/L)	0.653	0.543–0.786	<0.001
MCV (μm^3)	0.851	0.699–1.037	0.107
APACHE-II score (points)	4.200	3.152–5.594	<0.001
Log-eGFR (mL/min/1.73 m^2)	0.463	0.378–0.566	<0.001
Albumin (g/L)	0.505	0.406–0.626	<0.001
Log-CRP (mg/L)	1.779	1.431–2.211	<0.001

Odds ratios for continuous variables shown as standardized odds ratios (OR per 1 SD). Abbreviations as in Table I.

Table III. Independent predictors of ICU mortality by multivariate logistic regression analysis.

Predictor	Odds ratio	95% CI	P
RDW (%)	1.551	1.250–1.926	<0.001
APACHE-II score (points)	3.034	2.027–4.172	<0.001
Log-CRP (mg/L)	1.400	1.078–1.819	0.012

Independent variables included sex, age, log-eGFR (estimated glomerular filtration rate), log-CRP, hemoglobin, RDW, mean corpuscular volume, APACHE-II score, albumin, accompanying infection, pulmonary disease, and poisoning. Variables not listed in the table were removed from the stepwise analysis. Odds ratios for all variables shown as standardized odds ratios (OR per 1 SD). Abbreviations as in Table I.

Table IV. Independent predictors of TLSH by multivariate linear regression analysis.

Predictor	Unstandardized coefficients	Standardized coefficients	P
Age (years)	0.012	0.179	<0.001
RDW (%)	0.079	0.114	0.019
Log-CRP (mg/L)	0.129	0.097	0.039

Independent variables including sex, age, log-eGFR (estimated glomerular filtration rate), log-CRP, hemoglobin, RDW, mean corpuscular volume, Acute Physiology and Chronic Health Evaluation II (APACHE-II) score, albumin, accompanying infection, pulmonary disease, and poisoning. Variables not listed in the table were removed from the stepwise analysis.

TLSH = total length of stay in hospital; other abbreviations as in Table I.