Dynamic Increase of Red Cell Distribution Width Predicts Increased Risk of 30-Day Readmission in Patients with Acute Exacerbation of Chronic Obstructive Pulmonary Disease

Figures & data

Table 1 Baseline Characteristics of Three Groups

Variable	Normal Group (n=108)	Decreasing Group (n=72)	Increasing Group (n=59)	p value
Age, years (IQR)	72 (64, 81)	73 (65, 80)	73 (62, 82)	0.893
Male gender, n (%)	89 (82.4%)	61(84.7%)	49 (83.1%)	0.919
Current smoker, n (%)	24 (22.2%)	11 (15.3%)	12 (20.3%)	0.513
Charlson comorbidity index, (IQR)	5 (4, 6)	5 (4, 6)	5 (4, 6)	0.522
Heart rate, beats/min (IQR)	72.25 (82.00, 92.75)	72 (82, 86)	80 (72, 91)	0.256
Respiratory rate, breath/min (IQR)	19 (20, 23)	20 (20, 23)	19 (20, 23)	0.734
SO2<90% at admission, n (%)	44 (40.7%)	28 (38.9%)	24 (40.7%)	0.966
Systolic blood pressure, mmHg (SD)	120.19±15.37	116.32±13.57	116.54±15.95	0.155
Hypertension, n (%)	39 (36.1%)	22 (30.6%)	13 (22.0%)	0.171
Diabetes, n (%)	25 (23.1%)	9 (12.5%)	10 (16.9%)	0.453
CHF, n (%)	36 (33.3%)	25 (34.7%)	24 (40.7%)	0.629
CHD, n (%)	25 (23.1%)	23 (31.9%)	12 (20.3%)	0.258
Malignant tumor, n (%)	10 (9.3%)	9 (12.5%)	8 (13.6%)	0.654
ICU admission, n (%)	13 (12.0%)	5 (6.9%)	6 (10.2%)	0.539
WBC,10^9/L (IQR)	8.35 (6.40, 10.43)	7.05 (5.72, 9.48)	8.30 (6.50, 11.40)	0.025
Neutrophils,10^9/L (IQR),	6.25 (4.22, 8.87)	4.78 (3.58, 7.27)	6.56 (4.72, 9.79)	0.015
Lymphocytes,10^9/L (IQR)	1.20 (0.78, 1.73)	1.30 (0.79, 1.68)	1.02 (0.82, 1.37)	0.123
NLR, (IQR)	4.77 (2.93, 10.42)	3.84 (2.04, 8.00)	6.04 (4.12, 10.94)	0.033
Hemoglobin, g/L (SD)	130.76±18.39	126.01±26.25	121.39±22.83	0.031
PLT, 10^9/L (IQR)	208.5 (168.0, 254.8)	188.0 (140.5, 264.8)	218.0 (174.0, 293.0)	0.109
PLR, (IQR)	173.8 (110.6, 258.3)	167.1 (97.0, 230.5)	216.5 (148.8, 308.2)	0.015
PDW, fL (IQR)	12.6 (11.3, 14.2)	12.7 (11.3, 14.6)	12.9 (10.7, 14.2)	0.718
C-reactive protein, mg/l (IQR)	35.2 (9.3, 98.9)	12.59 (4.6, 36.1)	20.1 (7.2, 100.5)	0.018
Procalcitonin>0.05, n (%)	54 (50%)	32 (44.4%)	32 (54.2%)	0.530
D-dimer, ug/mL (IQR)	0.61 (0.40, 1.22)	0.80 (0.51, 1.88)	0.87 (0.51, 1.39)	0.055
Creatinine, ummol/l (SD)	69.30±40.47	70.86±47.62	62.47±27.60	0.452
pH<7.35, n (%)	25 (23.1%)	15 (20.8%)	13 (22%)	0.935
PaCO2>45mmHg, n (%)	60 (55.6%)	33 (45.8%)	34 (57.6%)	0.322
PaO2<80mmHg, n (%)	75 (69.4%)	42 (58.3%)	45 (76.3%)	0.082
Length of stay, days (IQR)	10 (8,14)	11 (8,15)	10 (8,13)	0.673
30-day readmission, n (%)	10 (9.3%)	7(9.7%)	16 (27.1%)	0.003
Number of admissions due to acute exacerbations during the previous year, (IQR)	0 (0, 1)	1 (0, 1)	0 (0, 1)	0.070

Abbreviations: COPD, chronic obstructive pulmonary disease; SO2, oxygen saturation; ICU, respiratory intensive care unit; CHF, chronic heart failure; CHD, coronary heart disease; WBC, white blood cell; NLR, neutrophil-lymphocyte ratio; PLT, platelets count; PLR, platelet-lymphocyte ratio; PDW, platelet distribution width; PO2, partial pressure of oxygen; PCO2, partial pressure of carbon dioxide.

Figure 1 Flow diagram of enrolled patients.

Table 2 Logistic Regression Analysis Between Demographic Factors, Vital Signs at Admission, Laboratory Test Results and 30-Day Readmission

Variable	Univariate Analysis		Multivariate Analysis
	OR (95% CI)	p-value	OR (95% CI)	p-value
Age	1.01 (0.97–1.04)	0.744
Male gender	0.89 (0.34–2.32)	0.811
Current smoker	1.37 (0.58–3.27)	0.477
Charlson comorbidity index	1.15 (0.95–1.40)	0.164	1.38 (1.08–1.76)	0.011
Heart rate at admission	0.97 (0.94–1.01)	0.123
Respiratory rate at admission	1.00 (0.90–1.13)	0.942
SO2<90% at admission	0.61 (0.28–1.34)	0.216
Systolic blood pressure<100mmHg at admission	1.04 (0.29–3.76)	0.947
Hypertension	0.68 (0.29–1.59)	0.371
Diabetes	0.96 (0.31–2.94)	0.936
Chronic heart failure	1.04 (0.49–2.24)	0.918
Coronary heart disease	0.26 (0.08–0.89)	0.032	0.13 (0.03–0.54)	0.005
Malignant tumor	2.50 (0.97–6.50)	0.059
Group: Normal group	–	–	–	–
Decreased group	1.06 (0.38–2.91)	0.917	1.12 (0.39–3.20)	0.828
Increased group	3.65 (1.53–8.68)	0.003	3.45 (1.39–8.58)	0.008
Hemoglobin	1.00 (0.99–1.02)	0.766
C-reactive protein	1.00 (0.99–1.00)	0.373
Procalcitonin>0.05	0.72 (0.34–1.52)	0.391
pH<7.35 at discharge	2.30 (1.05–5.05)	0.038	2.43 (1.04–5.69)	0.041
PaCO2>45mmHg at discharge	1.42 (0.67–3.01)	0.356
PaO2<80mmHg at discharge	0.94 (0.43–2.06)	0.883
Length of stay	0.97 (0.90–1.04)	0.368
Hospitalized due to AECOPD during the previous year	1.43 (0.68–3.03)	0.347

Abbreviations: OR, odds ratios; 95% CI, 95% confidence intervals; RDW, red cell distribution width; SO2, oxygen saturation; PO2, partial pressure of oxygen; PCO2, partial pressure of carbon dioxide.

Figure 2 Adjusted survival curve for 30-day all-cause readmission according to RDW group (p=0.015).