Red Cell Distribution Width/Albumin Ratio: A Predictor of In-Hospital All-Cause Mortality in Patients with Acute Myocardial Infarction in the ICU

Figures & data

Figure 1 Flowchart of study participant selection. *Key information refers to mortality, body mass index (BMI), acute physiology and chronic health evaluation (APACHE) score, hospital length of stay, intensive care unit (ICU) length of stay, and mechanical ventilation use.

Table 1 Baseline Clinical Features of the Enrolled Participants, Survivors, and Non-Survivors

Variables	Overall (2594)	Survivor (2276)	Non-Survivor (318)	p
Demographics
Age, years	66.00 (57.00–76.00)	66.00 (56.00–75.00)	72.00 (65.00–80.00)	<0.001
Female, n (%)	1634 (63.00%)	1459 (64.10%)	175 (55.03%)	0.002
BMI, (kg/m2)	28.00 (24.00–32.00)	28.00 (25.00–32.00)	27.00 (24.00–31.00)	<0.001
Ethnicity*, n (%)				0.084
African	236 (9.20%)	216 (9.60%)	20 (6.35%)
Asian	42 (1.64%)	35 (1.56%)	7 (2.22%)
Caucasian	2008 (78.28%)	1749 (77.73%)	259 (82.22%)
Hispanic	96 (3.74%)	85 (3.78%)	11 (3.49%)
Native	10 (0.39%)	7 (0.31%)	3 (0.95%)
Other	173 (6.74%)	158 (7.02%)	15 (4.76%)
Past medical history, n (%)
Hypertension	1495 (57.74%)	1329 (58.49%)	166 (52.37%)	0.039
Diabetes	929 (35.88%)	812 (35.74%)	117 (36.91%)	0.684
Previous MI	512 (19.78%)	457 (20.11%)	55 (17.35%)	0.247
CHF	402 (15.53%)	332 (14.61%)	70 (22.08%)	<0.001
PCI	378 (14.60%)	338 (14.88%)	40 (12.62%)	0.286
CABG	250 (9.66%)	216 (9.51%)	34 (10.73%)	0.491
Characteristics of the hospitalization
LOS_hosp, days	5.36 (2.83–10.05)	5.41 (2.85–9.84)	5.10 (2.40–11.06)	0.542
LOS_ICU, hours	51.00 (29.00–111.00)	48.00 (28.00–97.00)	95.00 (42.25–196.00)	<0.001
APACHE score	50.00 (36.00–69.00)	47.00 (35.00–62.25)	85.00 (66.00–113.75)	<0.001
STEMI, n (%)	1196 (46.11%)	1076 (47.28%)	120 (37.74%)	0.001
MV, n (%)	1680 (64.76%)	1400 (61.51%)	280 (88.05%)	<0.001

Note: *The discrepancy between the total number of patients and the actual number was due to missing data.

Abbreviations: BMI, body mass index; MI, myocardial infarction; CHF, chronic heart failure; PCI, percutaneous coronary intervention; CABG, coronary artery bypass grafting; LOS_hosp, hospital length of stay; LOS_ICU, ICU length of stay; APACHE, acute physiology and chronic health evaluation; STEMI, ST-segment elevation myocardial infarction; MV, mechanical ventilation.

Table 2 Baseline Laboratory Features in Survivors and Non-Survivors

Variables	Overall (2594)	Survivor (2276)	Non-Survivor (318)	p
Laboratory variables of admission
WBC, k/mcl	11.20 (8.50–14.78)	10.90 (8.40–14.20)	13.66 (10.03–18.67)	<0.001
RBC, m/mcl	4.34 (3.76–4.82)	4.39 (3.80–4.85)	4.09 (3.47–4.53)	<0.001
Hb, g/dl	13.10 (11.20–14.60)	13.20 (11.38–14.70)	12.10 (10.20–13.90)	<0.001
RDW, %	14.00 (13.30–15.10)	13.90 (13.20–15.00)	14.65 (13.60–16.00)	<0.001
Platelets, k/mcl	221.00 (176.00–274.00)	221.00 (176.00–273.00)	222.50 (163.75–284.00)	0.946
Creatinine, mg/dl	1.12 (0.86–1.60)	1.10 (0.84–1.52)	1.40 (1.05–2.18)	<0.001
BUN, mg/dl	20.00 (14.00–31.00)	19.00 (14.00–29.00)	27.00 (18.00–45.00)	<0.001
Albumin, g/dl	3.40 (2.90–3.80)	3.40 (3.00–3.80)	2.95 (2.50–3.40)	<0.001
ALT, U/L	32.00 (21.00–55.00)	31.00 (21.00–51.00)	41.00 (23.00–103.25)	<0.001
AST, U/L	46.00 (27.00–112.00)	43.00 (27.00–104.00)	77.00 (37.00–206.00)	<0.001
TB, mg/dl	0.60 (0.40–0.90)	0.60 (0.40–0.90)	0.70 (0.40–1.10)	0.003
TP, g/dl	6.60 (6.00–7.20)	6.60 (6.00–7.20)	6.20 (5.50–6.90)	<0.001
Potassium, mol/L	4.10 (3.70–4.50)	4.00 (3.70–4.40)	4.20 (3.70–4.70)	0.001
Sodium, mmol/L	138.00 (135.00–140.00)	138.00 (135.00–140.00)	138.00 (135.00–141.00)	0.828
Calcium, mg/dl	8.80 (8.30–9.30)	8.80 (8.40–9.30)	8.50 (8.00–9.10)	<0.001
Magnesium, mg/dl	1.90 (1.70–2.10)	1.90 (1.70–2.10)	2.00 (1.70–2.20)	0.031
Bicarbonate, mol/L	24.00 (21.00–26.00)	24.00 (22.00–26.00)	21.00 (18.00–25.00)	<0.001
APTT, sec	31.10 (27.10–40.40)	31.00 (27.00–39.50)	34.20 (28.13–47.00)	<0.001
INR	1.10 (1.00–1.30)	1.10 (1.00–1.22)	1.20 (1.10–1.50)	<0.001
Glucose, mg/dl	144.00 (116.00–206.00)	141.00 (114.00–199.00)	175.00 (132.00–249.00)	<0.001
TC, mg/dl	156.00 (127.00–187.00)	158.00 (129.00–190.00)	131.00 (105.00–162.00)	<0.001
Triglycerides, mg/dl	118.00 (83.00–172.00)	119.00 (84.00–172.00)	105.00 (78.50–172.00)	0.122
HDL, mg/dl	38.00 (30.00–46.00)	38.00 (31.00–46.00)	33.00 (24.00–47.00)	<0.001
LDL-C, mg/dl	88.00 (62.00–118.00)	89.00 (64.00–118.00)	72.00 (50.00–96.00)	<0.001
Troponin-I, ng/mL	1.56 (0.28–8.12)	1.51 (0.26–8.17)	1.82 (0.37–8.08)	0.249
ln-BNP	6.71 (5.56–7.88)	6.47 (5.44–7.68)	7.78 (6.69–9.27)	<0.001
RAR, %/g/dl	4.18 (3.64–5.03)	4.09 (3.59–4.87)	5.04 (4.17–6.16)	<0.001

Abbreviations: WBC, white blood cell; RBC, red blood cell; Hb, hemoglobin; RDW, red cell distribution width; BUN, blood urea nitrogen; ALT, alanine transaminase; AST, aspartate transaminase; TB, total bilirubin; TP, total protein; APTT, activated partial thromboplastin time; INR, international normalized ratio; TC, total cholesterol; HDL, high-density lipoprotein; LDL-C, low-density lipoprotein cholesterol; ln-BNP, the log-transformed brain natriuretic peptide; RAR, red cell distribution width/albumin ratio.

Figure 2 Receiver-operating characteristic curve of RAR, albumin, and RDW to predict in-hospital all-cause mortality of AMI.

Abbreviations: RAR, red cell distribution width/albumin ratio; RDW, red cell distribution width; AMI, acute myocardial infarction.

Figure 3 Receiver-operating characteristic curve of RAR and RAR combined with APACHE score to predict in-hospital all-cause mortality.

Abbreviations: RAR, red cell distribution width/albumin ratio; APACHE, Acute Physiology and Chronic Health Evaluation.

Table 3 Outcomes of the Patients with AMI Across Cutoff Points of the RAR

Variables	All Patients	RAR		p
		<4.776	≥4.776
n	2594	1782	812
LOS_hosp, days	5.36 (2.83–10.05)	4.27 (2.56–8.14)	8.06 (4.48–14.73)	<0.001
LOS_ICU, hours	51.00 (29.00–111.00)	45.00 (26.00–85.00)	81.00 (41.00–160.00)	<0.001
MV, n (%)	1680 (64.76%)	1071 (60.10%)	609 (75.00%)	<0.001
In-hospital mortality, n (%)	318 (12.26%)	130 (7.30%)	188 (23.15%)	<0.001

Abbreviations: RAR, red cell distribution width/albumin ratio; LOS_hosp, hospital length of stay; LOS_ICU, ICU length of stay; MV, mechanical ventilation.

Table 4 Results of Multivariable Logistic Regression of RAR and In-Hospital All-Cause Mortality

Exposure	Non-Adjusted		Model I		Model II
	OR/β	95% CI	OR/β	95% CI	OR/β	95% CI
Primary outcomes
Continuous variable
In-hospital mortality	1.48	(1.38, 1.58)	1.48	(1.38, 1.58)	1.27	(1.12, 1.43)
RAR cutoff point
In-hospital mortality
<4.776	1.0		1.0		1.0
≥4.776	3.83	(3.01, 4.88)	3.55	(2.77, 4.56)	1.62	(1.05, 2.51)
Secondary outcomes
Continuous variable
MV	1.31	(1.22, 1.40)	1.29	(1.21, 1.39)	1.31	(1.14, 1.50)
RAR cutoff point
MV
<4.776	1.0		1.0		1.0
≥4.776	1.99	(1.66, 2.40)	1.93	(1.60, 2.34)	1.83	(1.32, 2.54)
Length of ICU stay^a	17.15	(14.24, 20.06)	17.08	(14.11, 20.06)	8.28	(3.02, 13.53)
Length of hospital stay^a	1.65	(1.47, 1.84)	1.63	(1.43, 1.82)	0.92	(0.58, 1.25)

Notes: Model I was adjusted for age, sex, and ethnicity. Model II was adjusted for age; sex; ethnicity; past medical history: chronic heart failure, hypertension, diabetes; PCI, and CABG; AMI category; APACHE scores; white blood cell; red blood cell; hemoglobin; aspartate transaminase; alanine transaminase; blood urea nitrogen; creatinine; total bilirubin; total protein; glucose; potassium; sodium; calcium; magnesium; bicarbonate; activated partial thromboplastin time; international normalized ratio; troponin-I; and lnBNP. ^aLinear regression was used to evaluate the association between RAR and length of stay. The results are expressed as β (95% CIs).

Abbreviations: OR, odds ratio; CI, confidence interval; RAR, red cell distribution width/albumin ratio; MV, mechanical ventilation.

Table 5 Subgroup Assessments of the Associations of In-Hospital All-Cause Mortality with RAR

	n	RAR		P for Interaction
		<4.776	≥4.776
Age				0.4472
<65	1136	1.91 (0.92, 3.99)	1.01 (0.88, 1.15)
≥65	1458	1.13 (0.75, 1.71)	1.16 (1.06, 1.27)
Gender				0.1468
Male	960	1.42 (0.81, 2.49)	1.06 (0.96, 1.18)
Female	1634	1.33 (0.82, 2.14)	1.08 (0.97, 1.19)
AMI category				0.2031
NSTEMI	1398	1.00 (0.63, 1.59)	1.04 (0.95, 1.14)
STEMI	1196	2.56 (1.44, 4.52)	1.19 (1.04, 1.37)
MV				0.3938
No	914	0.37 (0.12, 1.13)	0.96 (0.73, 1.26)
Yes	1680	1.59 (1.08, 2.33)	1.08 (1.00, 1.16)
CHF				0.3597
No	2187	1.60 (1.09, 2.35)	1.08 (0.99, 1.17)
Yes	402	0.77 (0.28, 2.11)	1.05 (0.90, 1.22)
Diabetes				0.1363
No	1660	1.53 (0.99, 2.36)	1.04 (0.94, 1.15)
Yes	929	1.25 (0.66, 2.37)	1.11 (1.00, 1.24)
Hypertension				0.7854
No	1094	1.49 (0.89, 2.50)	1.07 (0.98, 1.17)
Yes	1495	1.39 (0.84, 2.30)	1.06 (0.94, 1.19)
Previous MI				0.7238
No	2077	1.46 (0.99, 2.15)	1.05 (0.97, 1.14)
Yes	512	1.23 (0.47, 3.24)	1.16 (1.00, 1.35)
APACHE score*				0.0800
T1	849	5.52 (0.61, 49.91)	1.20 (0.65, 2.21)
T2	851	0.85 (0.36, 2.01)	0.86 (0.63, 1.17)
T3	894	0.88 (0.58, 1.33)	1.06 (0.98, 1.14)

Note: *APACHE scores are grouped based on tertiles.

Abbreviations: RAR, red cell distribution width/albumin ratio; MV, mechanical ventilation; NSTEMI, Non ST-segment elevation myocardial infarction; STEMI, ST-segment elevation myocardial infarction; CHF, chronic heart failure; APACHE, acute physiology and chronic health evaluation.

Figure 4 Kaplan–Meier curve of RAR for estimating in-hospital all-cause mortality of AMI.

Abbreviations: RAR, red cell distribution width/albumin ratio; AMI, acute myocardial infarction.