Red Blood Cell Distribution and Survival in Patients with Chronic Obstructive Pulmonary Disease

Figures & data

Table 1.  Baseline characteristics of participants

Characteristic	All patients (n = 270)	Elevated RDW (>15.5) (n = 108)	Non-elevated RDW (≤15.5) (n = 162)	p-value
Demographics
Age (years)#	61 ± 7.3	61.8 ± 7.2	60 ± 7.4	NS
Gender (Male), (n,%)	207 (77)	96 (89)	111 (69)	NS
Smoking status
Pack-years of smoking£	40 (10–55)	40 (7.5–60)	38 (8–54)	NS
Active smoking, (n,%)	108 (40)	43 (39)	65 (40)	NS
Ex-smoker, (n,%)	116 (43)	52 (48)	64 (39)	NS
Time on disease (years)£	12 (6–20)	14 (7–20)	10 (5.7–16)	0.04
BMI (kg/m2)#	26.2 ± 5.2	24.2 ± 6.1	26.3 ± 4.7	NS
Medical history
CVD, (n,%)	40 (15)	23 (21)	17 (10)	0.023
Hypertension (n,%)	51 (19)	18 (17)	33 (20)	NS
Diabetes mellitus (n,%)	22 (8)	8 (7)	14 (9)	NS
Treatment modalities
LTOT (n,%)	87 (32)	36 (33)	51 (31)	NS
HNIMV (n,%)	24 (8)	13 (12)	11(6)	0.04
Inhaled steroid (n,%)	209 (76)	88 (82)	121 (74)	NS
GOLD stage; (n,%)
Stage I	14 (5)	4 (4)	10 (4)	NS
Stage II	38 (14)	18 (16)	20 (13)	NS
Stage III	116 (43)	50 (46)	66 (40)	NS
Stage IV	102 (38)	36 (34)	66 (40)	NS

RDW, red blood cell distribution (%); BMI, body mass index; GOLD, Global Initiative for Chronic Obstructive Lung Disease; CVD, Cardiovascular disease; HNIMV, home non-ınvasive mechanical ventilation; LTOT, long-term oxygen therapy; p-value, elevated versus non-elevated RDW, #Results given as Mean ± SD.£Results given as median (quarter intervals); n, number of cases; NS, statistically non-signifcant.

Table 2.  Follow-up dates and laboratory findings of the study participant

Dates	All patients (n = 270)	Elevated RDW (>15.5) (n = 108)	Non-elevated RDW (≤15.5) (n = 162)	p-value
Spirometry data
FEV1,% predicted£	33 (26-43)	32 (26-38)	34 (23-46)	NS
FEV1, L£	0.89(0.69-1.2)	0.93 (0.7-1.3)	0.8(0.6-1.2)	NS
FEV1/VC,%£	65 (51-71)	68 (54-75)	64 (51-70)	NS
Laboratory variables
PaO2 (mmHg)#	67 ± 12	65 ± 10	68 ± 13	NS
PaCO2 (mmHg)#	44 ± 7.6	46.7 ± 8.3	43 ± 6.9	0.03
pH£	7.4 (7.38-7.43)	7.39 (7.37–7.44)	7.4 (7.38–7.43)	NS
Albumin (g/dL)#	3.5 ± 0.5	3.3 ± 0.8	3.6 ± 0.5	0.04
RDW (%)#	15.1 ± 2.4	17.5 ± 2.1	13.6 ± 1	<0.001
Hb (g/dL)#	14.1 ± 3.4	13.2 ± 2.3	14.6 ± 3.8	0.004
MCV (fL)#	86 ± 7.5	83 ± 7.4	87 ± 7.2	<0.001
CRP (mg/dL)£	1.2 (0.5–3.2)	2.1 (0.7–4.5)	0.9 (0.5–2.3)	<0.001
Leukocytes,103/L£	8600 (7000–11,000)	8900 (6990–11300)	8600 (7025–10900)	NS
Neutrophils,103/L£	6150 (4125–8437)	6840 (4760–8760)	5700 (4430–8100)	NS
Electrocardiographic data
ST seg elevation, (n,%)	8 (3%)	2 (2%)	6 (4%)	NS
ST seg depression,(n,%)	29 (11%)	15 (14%)	14 (8%)	NS
T wave changes, (n,%)	45 (17%)	14 (13%)	31 (19%)	NS
Conduction bloc,(n,%)	62 (23%)	28 (26%)	34 (20%)	NS
Pathological Q-wave,(n,%)	21 (8%)	12 (11%)	9 (6%)	NS
Atrial fibrillation, (n,%)	19 (11%)	10 (9%)	9 (6%)	NS
Echocardiographic data
RVD, (n,%)	83 (30%)	44(41%)	39 (24	0.006
LVD, (n,%)	23 (8%)	11(10%)	%)12 (7%)	NS
PAH, (n,%)	131 (48%)	66 (61%)	65(40%)	0.02
LVEF (%)#	57 ± 8,3	56 ± 8.5	58 ± 9	NS
RVEDD,cm#	2.7 ± 0.6	2.8 ± 0.6	2.6 ± 0.6	0.041
LVEDD,cm#	4.7 ± 0.7	4.8 ± 0.6	4.6 ± 0.7	0.046
Follow-up, data
Follow-up, months£	36 (20-52)	22 (5-36)	38 (34-57)	<0.001
Re-admission, n£	1.1 (1-3)	2.1 (0-3)	1 (1-3)	NS
Mortality (n,%)	121 (45)	84 (78)	37 (23)	<0.001

RDW, red blood cell distribution (%); FEV1, forced expiratory volume in 1 second; FVC, forced vital capacity. LVEF, left ventricular ejection fraction; PAH, pulmonary arterial hypertension; RVD, riht ventrictular dysfunction; LVD; left ventricular dysfunction; RVEDD; right ventrictular end-diastolic diameter, LVEDD; left ventricular end-diastolic diameter; CRP; C-reactive protein; MCV; mean corpuscular volume; p-value, elevated versus non-elevated RDW, #Results given as Mean ± SD.£Results given as median (quarter intervals); n, number of cases; NS, statistically non-signifcant.

Figure 1.  Correlation coefficient between red cell distribution width (RDW) and the C-reactive protein (CRP). The scale is a logarithmic scale.

Table 3.  Correlation coefficients of demografic and laboratory variables with RDW

Variable	RDW
	r coefficient	p-value
Demographics variables	0.06	NS
Age	–0.05	NS
Gender	0.09	NS
Smoking status	–0.01	NS
BMI	0.01	NS
Time on disease	0.21	0.02
Cardiovascular disease	0.07	NS
LTOT	0.16	0.03
HNIMV	0.12	NS
Inhale steroid	0.08	NS
Stage
Spirometry variables
FEV1,% predicted	–0.08	NS
FEV1,	–0.01	NS
FEV1/VC,%	0.01	NS
Laboratory variables
PaO2	–0.04	NS
PaCO2	0.17	0.04
pH	–0.04	NS
Albumin	–0.22	0.02
Hb	–0.18	0.04
MCV	–0.37	<0.001
CRP	0.21	0.008
Leukocytes	–0.06	NS
Neutrophils	0.04	NS
Electrocardiographic variables
ST seg elevation	0.02	NS
ST seg depresslon	0.12	NS
T wave changes	–0.03	NS
Conduction bloc	0.07	NS
Pathological Q-wave	0.11	NS
Atrial fibrillation	0.12	NS
Echocardiographic variables
RVD	0.25	<0.001
LVD	–0.09	NS
PAH	0.14	0.03
LVEF	–0.15	0.023
RVEDD	0.17	0.03
LVEDD	0.15	0.04
Follow-up variables
Re-admission	0.2	NS
Mortality	0.46	<0.001

RDW, red blood cell distribution (%);BMI, body mass index; MCV; mean corpuscular volume;

HNIMV, home non-invasive mechanical ventilation; LTOT, long-term oxygen therapy;

LVEF, left ventricular ejection fraction; PAH, pulmonary arterial hypertension;

RVD, right ventrictular dysfunction; RVEDD; right ventrictular end-diastolic diameter,

LVEDD; left ventricular end-diastolic diameter; NS, statistically non-signifcant

LVD; left ventricular dysfunction.

Figure 2.  Unadjusted- Kaplan-Meier curve for long-term survival according to red cell distribution width (RDW) groups in the entire cohort of patients (p < 0.001 by log-rank test).

Figures 3. Adjusted with right ventricular dysfunction (RVD) Kaplan-Meier curve for long-term survival according to red cell distribution width (RDW) groups in the entire cohort of patients (p < 0.001 by log-rank test).

Figures 4. Adjusted with right ventricular dysfunction (RVD) Kaplan-Meier curve for long-term survival according to red cell distribution width (RDW) groups in the entire cohort of patients (p < 0.001 by log-rank test).

Table 4.  Univariate and multivariate analysis of risk factors for mortality in patients with COPD

Variables	Univariate analysis p-value OR (95% CI)	Multivariate analysis p-value OR (95% CI)
Age	0.07 1.025 (0.9–1.05)	0.08 1.03 (0.9–1.08)
Gender	0.7 1.08 (0.6–1.7)
Smoking status	0.3 1.1 (0.8–1.4)
Time on disease	0.8 0.9 (0.9–1.02)
BMI	0.2 0.9 (0.9–1.02)
Treatment modalities	0.11 1.4 (0.9–2.2)
Presence of CVD	0.03 1.7 (1.02–3.05)	0.26 1.79 (0.64–5.01)
Re-admission	0.79 1 (0.9–1.1)
Stages	0.23 1.3 (0.9–2)
FEV1, predicted%	0.06 0.97 (0.95–1.02)	0.52 0.9 (0.96–1.01)
FVC, predicted%	0.12 0.9 (0.96–1)
FEV1/FVC	0.16 0.8 (0.8–1)
PaO2	0,34 0.9 (0.9–1)
PaCO2	0.04 1.02 (1.009–1.3)	0.17 1.03 (0.9–1.8)
pH	0.22 1.02 (1.02–2.2)
Albumin	0.07 0.5 (0.3–0.8)	0.14 0.67 (0.4–1.1)
Presence of Anemia	0.06 1.4 (0.9–2.2)	0.4 1.4 (0.6–3.4)
CRP	0.05 1.02 (0.9–1.04)	0.41 1.02 (0.97–1.5)
RDW	<0.001 1.2 (1.15–1.3)	0.01 1.12 (1.01–1.24)
PAH	<0.001 1.02 (1.01–1.02)	0.18 1. 5 (0.8–2.9)
RVD	<0.001 2.57 (1.7–3.8)	0.01 2.6 (1.19–5.8)
LVD	0.88 0.95(0.5–1.7)

RDW, red blood cell distribution (%); FEV1, forced expiratory volume in 1 second; FVC, forced vital capacity. LVEF, left ventricular ejection fraction; CVD, Cardiovascular disease; PAH, pulmonary arterial hypertension; LVD; left ventricular dysfunction; RVD, right ventrictular dysfunction; CRP; C-reactive protein; BMI, body mass index; OR, odds ratio; CI, confidence interval.