Impact of anemia on short-term survival in severe COPD exacerbations: a cohort study

Figures & data

Table 1 General characteristics of study population

N	106
Sex
Male	83 (78.3)
Female	23 (21.7)
Age, years	71.0 (62.0–76.0)
Previous smoking history/active smoking	59 (55.7)/25 (23.6)
Pack-years	60.0 (60.0–96.3)
Pulmonary function testsa
FEV1 (liters)	0.79 (0.59–1.17)
FEV1 % predicted	31.4 (20.5–40.2)
Long-term oxygen therapy	37 (34.9)
Domiciliary NIV	15 (14.2)
Comorbidities
• Hypertension	60 (56.6)
• Coronary artery disease	35 (33.0)
• Diabetes mellitus	30 (28.3)
• Arrhythmia	22 (20.8)
• Congestive heart failure	21 (19.8)
GCS score	15.0 (8.0–15.0)
APACHE II score	23.0 (18.0–31.0)
Respiratory arrest before ICU admission	12 (11.3)
Length of stay (days) between hospital admission and ICU admission	1.0 (0.0–5.0)

Notes: All values are expressed as numbers (percentages) or median (interquartile range).

a Pulmonary function tests were available in 62 patients.

Abbreviations: APACHE, Acute Physiology and Chronic Health Evaluation; FEV₁, forced expiratory volume in 1 second; GCS, Glasgow Coma Scale; ICU, intensive care unit; NIV, noninvasive ventilation.

Figure 1 Study flowchart and hospital outcomes of the study population.

Abbreviations: ICU, intensive care unit; IMV, invasive mechanical ventilation; NIV, noninvasive ventilation.

Table 2 Clinical characteristics of study population

Mechanical ventilation support
Invasive ventilation	22 (20.8)
NIV	84 (79.2)
NIV failure	38 (35.8)
Duration of mechanical ventilation (days)	7.0 (3.0–18.0)
Admission arterial blood gas values
pH	7.26 (7.18–7.31)
PaCO2 (mmHg)	75.8 (62.7–85.1)
PaO2 (mmHg)	52.0 (40.4–64.5)
PaO2/FiO2	130.0 (101.0–161.3)
Lactate (mmol/L)	1.6 (1.1–2.5)
White blood cell count (×10^3/μL)	12.2 (8.7–17.3)
CRP (mg/L)	8.9 (3.5–13.5)
Hemoglobin (gm/dL)	12.8 (11.6–15.0)
Hematocrit (%)	40.8 (35.9–48.7)
MCV (fl)	88.3 (82.4–91.7)
Anemia	53 (50)
Polycythemia	1 (0.9)
ALB (gm/dL)	3.3 (2.9–3.6)
ICU length of stay (days)	13.0 (7.8–21.0)
Hospital length of stay (days)	20.0 (12.8–32.0)
ICU mortality	37 (34.9)
Hospital mortality	39 (36.8)

Note: All values are expressed as numbers (percentages) or median (interquartile range).

Abbreviations: ICU, intensive care unit; MCV, mean corpuscular volume; NIV, noninvasive ventilation; CRP, C-reactive protein; ALB, albumin.

Table 3 Statistically significant differences between noninvasive ventilation successful and failed patients (n=84)

Variables	NIV successful (n=46)	NIV failed (n=38)	P-value
APACHE II score	18.0 (15.8–22.0)	27.5 (20.0–32.8)	<0.001
GCS score	15.0 (15.0–15.0)	12.0 (5.5–15.0)	<0.001
Arrhythmia	7 (10.4)	15 (38.5)	0.041
Domiciliary NIV use	11 (23.9)	4 (10.5)	0.047
CRP (mg/L)	6.3 (1.8–13.3)	10.8 (6–16.4)	0.036
Hemoglobin (gm/dL)	14.0 (12.5–15.5)	11.9 (10.9–13.3)	<0.001
Hematocrit (%)	45.2 (38.9–51.2)	37.6 (34.6–42.2)	0.001
Anemia	14 (30.4)	26 (68.4)	0.001
Hospital length of stay (days)	15.0 (9.5–22.0)	23.5 (18.0–38.0)	0.001
Hospital mortality	0 (0.0)	25 (65.8)	<0.001

Note: All values are expressed as numbers (percentages) or median (interquartile range).

Abbreviations: APACHE, Acute Physiology and Chronic Health Evaluation; GCS, Glasgow Coma Scale; NIV, noninvasive ventilation; CRP, C-reactive protein.

Table 4 Statistically significant differences between anemic and nonanemic patients

Variables	Anemic patients (n=53)	Nonanemic patients (n=53)	P-value
Age (years)	74.0 (65.0–78.0)	70 (59.0–74.0)	0.018
FEV1 % predicteda	25.7 (13.5–35.2)	32.0 (25.0–46.9)	0.042
APACHE II score	26.0 (19.0–31.5)	21.0 (17.0–29.0)	0.016
Coronary artery disease	23 (43.4)	12 (22.6)	0.038
Arrhythmia	17 (32.1)	5 (9.4)	0.007
Hemoglobin (gm/dL)	11.6 (10.2–12.3)	15.0 (13.7–16.1)	<0.001
NIV failure	26 (49.0)	12 (22.6)	0.001
Hospital length of stay (days)	26.0 (13.5–40.0)	18.0 (11.5–24.5)	0048
Hospital mortality	28 (52.8)	11 (20.8)	0.001

Notes: All values are expressed as numbers (percentages) or median (interquartile range).

a Available in 62 patients.

Abbreviations: APACHE, Acute Physiology and Chronic Health Evaluation; FEV₁, forced expiratory volume in 1 second; NIV, noninvasive ventilation.

Figure 2 Correlations between hemoglobin concentration and age and FEV₁% predicted.

Notes: (A) The correlation between hemoglobin and age (Spearman’s correlation coefficient: −0.293; P=0.002). (B) The correlation between hemoglobin and FEV₁ % predicted (n=62; Spearman’s correlation coefficient: 0.388; P=0.011).

Abbreviation: FEV₁, forced expiratory volume in 1 second.

Figure 3 Hemoglobin levels in anemic and nonanemic patients.

Table 5 Statistically significant factors related with hospital mortality

Variables	Survivors (n=67)	Nonsurvivors (n=39)	P-value
APACHE II score	20.0 (17.0–28.0)	28.0 (22.0–34.0)	<0.001
GCS score	15.0 (12.0–15.0)	10.0 (5.0–10.0)	<0.001
Arrhythmia	7 (10.4)	15 (38.5)	0.001
Domiciliary NIV use	13 (19.4)	2 (5.1)	0.047
NIV failure	13 (19.4)	25 (64.1)	<0.001
CRP (mg/L)	6.9 (1.9–12.5)	11.0 (5.9–17.3)	0.009
Hemoglobin (gm/dL)	13.6 (12.4–15.5)	11.6 (10.3–13.3)	<0.001
Hematocrit (%)	42.6 (38.7–50.5)	36.5 (32.2–43.7)	<0.001
Anemia	25 (37.3)	28 (71.8)	0.001
ALB (gm/dL)	3.4 (3.0–3.7)	3.0 (2.7–3.3)	0.003
Hospital length of stay (days)	17 (12–25)	26 (16–39)	0.030

Note: All values are expressed as numbers (percentages) or median (interquartile range).

Abbreviations: APACHE, Acute Physiology and Chronic Health Evaluation; GCS, Glasgow Coma Scale; NIV, noninvasive ventilation; CRP, C-reactive protein; ALB, albumin.

Table 6 Stepwise multivariate logistic regression analysis for independent predictors of hospital mortality

Variable	Odds ratio	95% confidence interval	P-value
Age	1.00	0.93–1.06	0.874
APACHE II score	0.97	0.90–1.05	0.470
GCS score	0.90	0.78–1.03	0.123
Arrhythmia	2.80	0.89–8.87	0.080
Domiciliary NIV	0.32	0.07–2.38	0.323
ALB	0.47	0.18–1.29	0.146
NIV failure	2.56	1.60–4.09	<0.001
Anemia	3.99	1.39–11.40	0.010

Abbreviations: APACHE, Acute Physiology and Chronic Health Evaluation; GCS, Glasgow Coma Scale; NIV, noninvasive ventilation; ALB, albumin.