Red blood cell distribution width to albumin ratio is correlated with prognosis of patients in coronary care unit

Table 1 Baseline characteristics of the study population, n (%)

Characteristics	RA < 3.84 (n = 739)	RA 3.84-4.66 (n = 736)	RA > 4.66 (n = 743)	P value
RA	3.45 ± 0.28	4.20 ± 0.23	5.89 ± 1.37	< 0.001
Clinical parameters
Age, years	63.86 ± 15.31	70.18 ± 14.98	70.36 ± 14.75	< 0.001
Gender				< 0.001
Male	510 (69.01)	393 (53.40)	404 (54.37)
Female	229 (30.99)	343 (46.60)	339 (45.63)
Ethnicity				0.038
White	497 (67.25)	523 (71.06)	510 (68.64)
Black	46 (6.22)	54 (7.34)	69 (9.29)
Other	196 (26.52)	159 (21.60)	164 (22.07)
Vital signs
MAP, mmHg	80.33 ± 10.91	77.51 ± 11.50	74.03 ± 11.40	< 0.001
Heart rate, times/minute	79.21 ± 15.91	80.94 ± 15.62	85.06 ± 17.20	< 0.001
RR, times/minute	18.52 ± 3.44	19.30 ± 3.88	19.67 ± 4.23	< 0.001
Temperature, °C	36.79 ± 0.60	36.79 ± 0.75	36.68 ± 0.82	0.001
SpO2, %	97.19 ± 1.79	96.89 ± 2.58	96.87 ± 3.65	0.047
Comorbidities
CHF	163 (22.06)	256 (34.78)	241 (32.44)	< 0.001
Atrial fibrillation	190 (25.71)	271 (36.82)	303 (40.78)	< 0.001
COPD	15 (2.03)	19 (2.58)	12 (1.62)	0.425
CAD	477 (64.55)	435 (59.10)	348 (46.84)	< 0.001
Pulmonary circulation	122 (16.51)	192 (26.09)	264 (35.53)	< 0.001
Renal failure	73 (9.88)	155 (21.06)	199 (26.78)	< 0.001
Laboratory parameters
Albumin, g/dL	3.93 ± 0.33	3.44 ± 0.29	2.87 ± 0.51	< 0.001
Serum creatinine, mg/dL	1.17 ± 1.17	1.51 ± 1.34	2.04 ± 1.82	< 0.001
Glucose, mg/dL	121.72 ± 41.36	119.21 ± 39.28	113.50 ± 45.35	< 0.001
Serum urea nitrogen, mg/dL	21.15 ± 16.61	29.52 ± 20.64	38.54 ± 27.38	< 0.001
Hematocrit, %	34.03 ± 5.84	31.13 ± 5.19	29.03 ± 5.35	< 0.001
Hemoglobin, g/dL	11.75 ± 2.05	10.56 ± 1.79	9.64 ± 1.75	< 0.001
WBC, 109/L	9.97 ± 3.80	10.27 ± 4.35	11.17 ± 6.79	0.158
Platelet, 109/L	210.02 ± 68.56	213.47 ± 88.36	216.30 ± 105.17	0.722
RDW, fl	13.52 ± 0.88	14.43 ± 1.18	16.41 ± 2.24	< 0.001
Sodium, mmol/L	136.35 ± 4.25	136.19 ± 4.96	135.86 ± 5.63	0.030
Potassium, mmol/L	3.73 ± 0.48	3.79 ± 0.54	3.84 ± 0.64	0.002
INR	1.27 ± 0.48	1.42 ± 0.69	1.60 ± 0.85	< 0.001
PT, second	14.09 ± 3.93	15.33 ± 5.56	16.54 ± 6.09	< 0.001
Scoring system
SOFA	3.21 ± 2.58	4.24 ± 2.96	5.67 ± 3.41	< 0.001
Primary outcome
365-day mortality	96 (12.99)	172 (23.37)	307 (41.32)	< 0.001
Secondary outcomes
30-day mortality	54 (7.31)	93 (12.64)	167 (22.48)	< 0.001
90-day mortality	70 (9.47)	120 (16.30)	218 (29.34)	< 0.001
Hospital LOS, day	7.12 ± 6.53	9.42 ± 9.55	11.84 ± 11.05	< 0.001
CCU LOS, day	3.69 ± 4.29	4.76 ± 6.34	5.88 ± 7.41	< 0.001

Hazard ratios (95% confidence interval) were derived from Cox proportional hazards regression models. The data came from patients in Medical Information Mart for Intensive Care III database. RA: Red blood cell distribution width to albumin; MAP: Mean arterial pressure; RR: Respiratory rate; SpO₂: Pulse oximetry-derived oxygen saturation; CHF: Congestive heart failure; COPD: Chronic obstructive pulmonary disease; CAD: Coronary atherosclerotic heart disease; WBC: White blood cell; RDW: Red blood cell distribution width; INR: International normalized ratio; PT: Prothrombin time; SOFA: Sequential organ failure assessment; LOS: Length of stay; CCU: Coronary care unit.

Table 2 The β value or hazard ratios or odds ratio for outcomes across groups of red blood cell distribution width-to-albumin ratios (95% confidence interval)

Mortality	Non-adjusted, HR	Non-adjusted, P value	Adjust I, HR	Adjust I, P value	Adjust II, HR	Adjust II, P value	PSM, OR	PSM, P value
365-day all-cause mortality
RA	1.18 (1.12, 1.25)	< 0.001	1.20 (1.13, 1.26)	< 0.001	1.08 (1.01, 1.15)	0.026	1.24 (1.10, 1.41)	< 0.001
Tertiles < 3.84	1.00		1.00		1.00		1.00
Tertiles 3.84-4.66	1.09 (0.85, 1.41)	0.478	1.09 (0.85, 1.40)	0.499	1.02 (0.79, 1.34)	0.859	1.28 (0.87, 1.87)	0.209
Tertiles > 4.66	1.62 (1.29, 2.03)	< 0.001	1.65 (1.31, 2.08)	< 0.001	1.30 (1.01, 1.69)	0.045	1.92 (1.28, 2.89)	0.002
30-day all-cause mortality
RA	1.14 (1.06, 1.22)	< 0.001	1.16 (1.08, 1.24)	< 0.001	1.01 (0.93, 1.10)	0.839
Tertiles < 3.84	1.00		1.00		1.00
Tertiles 3.84-4.66	1.03 (0.74, 1.44)	0.863	1.05 (0.75, 1.48)	0.765	0.99 (0.68, 1.43)	0.944
Tertiles > 4.66	1.40 (1.03, 1.90)	0.032	1.45 (1.06, 1.97)	0.019	1.06 (0.73, 1.52)	0.770
90-day all-cause mortality
RA	1.17 (1.10, 1.25)	< 0.001	1.19 (1.12, 1.27)	< 0.001	1.05 (0.97, 1.13)	0.198
Tertiles < 3.84	1.00		1.00		1.00
Tertiles 3.84-4.66	1.02 (0.76, 1.37)	0.879	1.03 (0.77, 1.39)	0.837	0.96 (0.70, 1.32)	0.795
Tertiles > 4.66	1.45 (1.11, 1.89)	0.007	1.49 (1.14, 1.95)	0.004	1.10 (0.81, 1.50)	0.545
Hospital LOS, β, days
RA	1.70 (1.41, 1.99)	< 0.001	1.76 (1.46, 2.06)	< 0.001	1.20 (0.85, 1.55)	< 0.001
Tertiles < 3.84	0.00		0.00		0.00
Tertiles 3.84-4.66	2.30 (1.36, 3.24)	< 0.001	2.54 (1.58, 3.51)	< 0.001	1.54 (0.52, 2.56)	0.003
Tertiles > 4.66	4.72 (3.77, 5.66)	< 0.001	4.98 (4.02, 5.94)	< 0.001	2.73 (1.61, 3.85)	< 0.001
CCU LOS, β, days
RA	0.66 (0.47, 0.86)	< 0.001	0.72 (0.52, 0.92)	< 0.001	0.23 (0.00, 0.46)	0.047
Tertiles < 3.84	0.00		0.00		0.00
Tertiles 3.84-4.66	1.07 (0.44, 1.70)	< 0.001	1.23 (0.59, 1.87)	< 0.001	0.67 (0.00, 1.34)	0.049
Tertiles > 4.66	2.20 (1.57, 2.82)	< 0.001	2.37 (1.73, 3.01)	< 0.001	0.80 (0.06, 1.53)	0.034

Non-adjusted and adjust I and II and propensity score matching were derived from Cox proportional hazards regression models. Adjust I covariates were adjusted for age, gender and ethnicity. Adjust II covariates were adjusted for age, gender, ethnicity, glucose, hematocrit, potassium, international normalized ratio, sodium, serum urea nitrogen, white blood cell, heart rate, respiratory rate, temperature, pulse oximetry-derived oxygen saturation_, coronary atherosclerotic heart disease, congestive heart failure, atrial fibrillation, chronic obstructive pulmonary disease, sequential organ failure assessment. propensity score matching further adjusted for age, ethnicity, respiratory rate, congestive heart failure, serum creatinine, serum urea nitrogen, hematocrit, hemoglobin, potassium, prothrombin time based on Supplementary Table 2. HR: Hazard ratio; PSM: Propensity score matching; OR: Odds ratio; RA: Red blood cell distribution width to albumin; LOS: Length of stay; CCU: Coronary care unit.