Determining prognosis in acute exacerbation of COPD

Figures & data

Table 1 Baseline characteristics for total population and for each group of the primary outcome with non-adjusted hazard ratio

	Total population		Death or readmission (242)		No death/readmission (117)		Nonadjusted hazard ratio (95% CI)
	n	Characteristics	n	Characteristics	n	Characteristics
Age, median (range)	359	74 (41–96)	242	75 (41–96)	117	69 (46–91)	1.026 (1.01–1.04)
Male gender (%)	359	195 (54)	242	55.4	117	52.1	1.12 (0.81–1.53)
Comorbidities
High blood pressure, n (%)	359	201 (56)	242	136 (56)	117	65 (56)	0.98 (0.76–1.27)
Diabetes, n (%)	359	65 (18)	242	49 (20)	117	16 (14)	1.61 (1.17–2.20)
Dyslipidemia, n (%)	359	108 (30)	242	76 (31)	117	32 (27)	1.07 (0.82–1.41)
Coronary artery disease, n (%)	359	75 (21)	242	55 (23)	117	20 (17)	1.49 (1.10–2.02)
Atrial fibrillation, n (%)	359	54 (15)	242	42 (17)	117	12 (10)	1.41 (1.016–1.98)
Heart failure, n (%)	359	66 (18)	242	53 (22)	117	13 (11)	1.54 (1.14–2.1)
Stroke, n (%)	359	18 (5)	242	15 (6)	117	3 (3)	1.62 (0.96–2.74)
Acute/chronic renal failure, n (%)	359	74 (21)	242	54 (22)	117	20 (17)	1.46 (1.08–1.99)
Cancer, n (%)	359	26 (7)	242	22 (9)	117	4 (3)	1.73 (1.11–2.69)
Pulmonary cancer, n (%)	359	17 (5)	242	13 (5)	117	4 (3)	1.62 (0.92–2.84)
Osteoporosis, n (%)	359	47 (13)	242	36 (15)	117	11 (9)	1.24 (0.87–1.77)
Active smokers, n (%)	358	165 (46)	242	107 (44)	116	58 (50)	1.02 (0.61–1.70)
Pulmonary function
Mild or moderate COPD (FEV1 ≥50%), n (%)	306	93 (30)	220	57 (26)	86	36 (41)	0.63 (0.47–0.86)
Vital parameters at admission
Heart rate (beats per min), median (range)	335	98 (54–220)	223	100 (54–200)	112	93 (59–151)	1.008 (1.002–1.014)
Respiratory rate (1/min), median (range)	322	24 (11–50)	215	26 (11–50)	107	22 (11–42)	1.03 (1.01–1.05)
Weight (kg), median (range)	328	65 (28–138)	221	64 (36–138)	107	67 (28–124)	0.99 (0.98–0.99)
Laboratories values (at admission)
Hemoglobin level (g/L), median (range)	357	137 (71–210)	242	136 (71–210)	115	141 (84–197)	0.09 (0.98–0.99)
Creatinine (g/L), median (range)	358	76 (35–905)	242	77 (36–905)	116	73 (35–318)	1.003 (1.001–1.004)
Potassium (mmol/L), median (range)	355	4.1 (3–6.8)	240	4.1 (3–6.8)	115	4 (3–6.2)	1.50 (1.20–1.87)
Albumin (g/L), median (range)	174	31 (16–40)	127	31 (16–40)	47	32 (19–39)	0.96 (0.92–0.99)
PaCO2 (kPa), median (range)	318	5.64 (2.66–17.5)	216	5.78 (2.66–17.5)	102	5.12 (3.37–9.45)	1.11 (1.032–1.2)
pH, median (range)	318	7.41 (6.98–7.63)	216	7.41 (6.98–7.54)	102	7.41 (7.26–7.63)	0.09 (0.01–0.59)
Procalcitonin (µg/L), median (range)	184	0.11 (0.02–240)	128	0.12 (0.03–240)	56	0.1 (0.02–2.35)	1.006 (0.99–1.013)

Notes: n: number of available data. P-value in bold when <0.05. Range is minimum–maximum.

Abbreviations: CI, confidence interval; FEV₁, forced expiratory volume in 1 s; PaCO₂, partial pressure of carbon dioxide.

Figure 1 Kaplan–Meier curve of survival without death or new readmission (primary outcome) in patients with an exacerbation of COPD.

Note: 95%CI is in dashed lines.
Abbreviation: CI, confidence interval.

Table 2 Multivariate analysis for the primary outcome (death or readmission)

Variables	Hazard ratio (95% CI)	P-value
Age	1.03 (1.02–1.05)	<0.0001
Severity of COPD	Reference (FEV1 ≥80%)
50%≤ FEV1 <80%	2.17 (0.67–7.05)	0.20
30%≤ FEV1 <50%	3.17 (1.00–10.6)	0.051
FEV1 <30%	4.65 (1.42–15.1)	0.01
Diabetes II	1.47 (1.003–2.16)	0.048
Cancer	2.79 (1.68–4.64)	<0.0001
Creatinine at admission (µmol/L)	1.003 (1.0004–1.006)	0.02
Respiratory rate (at admission)	1.03 (1.003–1.05)	0.028

Notes: 269 patients analyzed, with 191 events (90 observations not included due to missing data). Values in bold indicate P<0.05.

Abbreviations: CI, confidence interval; FEV₁, forced expiratory volume in 1 s.

Table 3 Multivariate analysis for the primary outcome with predictive miss-matching data imputation

Variables	Hazard ratio (95% CI)	P-value
Age	1.02 (1.009–1.038)	0.001
Severity of COPD	Reference (FEV1 ≥80%)
50%≤ FEV1 <80%	1.47 (0.53–4.09)	0.45
30%≤ FEV1 <50%	2.06 (0.75–5.66)	0.15
FEV1 <30%	2.65 (0.94–7.49)	0.06
Diabetes II	1.80 (1.28–2.54)	0.0006
Cancer	1.60 (1.01–2.53)	0.043
Creatinine at admission (µmol/L)	1.03 (1.005–1.05)	0.01
PaCO2 at admission (kPa)	1.11 (1.02–1.20)	0.007
Procalcitonin at admission (µg/L)	1.005 (0.99–1.01)	0.17
Albumin at admission (mmol/L)	0.97 (0.94–1.003)	0.08
Blood pressure at admission (mmHg)	0.99 (0.98–0001)	0.054
Respiratory rate at admission	1.03 (1.01–1.05)	0.002
Weight at admission (kg)	0.99 (0.98–0.99)	0.03

Note: P-value in bold when <0.05.

Abbreviations: CI, confidence interval; FEV₁, forced expiratory volume in 1 s; PaCO₂, partial pressure of carbon dioxide.

Table 4 Baseline characteristics for total population and for each group of the secondary outcome (death) with nonadjusted and adjusted hazard ratio

	Total population		Death (140)		No death (219)		Nonadjusted hazard ratio (95% CI)*	Adjusted hazard ratio (95% CI)***
	n	Characteristics	n	Characteristics	n	Characteristics
Age, median (range)	359	74 (41–96)	140	78 (48–96)	219	70 (41–91)	1.055 (1.036–1.074)**	1.12 (1.05–1.19)
Male gender (%)	359	195 (54)	140	77 (55)	219	118 (54)	1.12 (0.8–1.6)	–
Comorbidities
High blood pressure, n (%)	359	201 (56)	140	84 (60)	219	117 (53)	1.33 (0.95–1.9)	–
Diabetes, n (%)	359	65 (18)	140	34 (24)	219	31 (14)	1.56 (1.06–2.3)	1.76 (0.63–4.91)
Dyslipidemia, n (%)	359	108 (30)	140	48 (34)	219	60 (27)	1.21 (0.85–1.72)	–
Coronary artery disease (%)	359	75 (21)	140	35 (25)	219	40 (18)	1.60 (1.09–2.35)	0.56 (0.20–1.61)
Atrial fibrillation, n (%)	359	54 (15)	140	30 (21)	219	24 (11)	1.86 (1.24–2.79)	1.02 (0.32–3.24)
Heart failure, n (%)	359	66 (18)	140	32 (23)	219	34 (16)	1.37 (0.92–2.03)	–
Stroke, n (%)	359	18 (5)	140	11 (8)	219	7 (3)	1.77 (0.95–3.30)	–
Acute/chronic renal failure, n (%)	359	74 (21)	140	36 (26)	219	38 (17)	1.80 (1.23–2.64)	0.57 (0.16–2.09)
Cancer, n (%)	359	26 (7)	140	18 (13)	219	8 (4)	2.60 (1.58–4.26)**	7.04 (2.22–22.36)
Pulmonary cancer, n (%)	359	17 (5)	140	11 (8)	219	6 (3)	2.67 (1.44–4.95)**	–
Osteoporosis, n (%)	359	47 (13)	140	25 (18)	219	22 (10)	1.49 (0.96–2.29)	–
Active smokers, n (%)	358	165 (46)	140	58 (41)	218	107 (49)	0.75 (0.53–1.045)	–
Pulmonary function
Mild or moderate COPD (FEV1 ≥50%), n (%)	306	93 (30)	125	93 (66)	181	120 (55)	0.75 (0.51–1.13)	–
Vital parameters at admission
Heart rate (beats per min), median (range)	335	98 (54–220)	131	100 (54–167)	204	96.5 (56–200)	1.004 (0.996–1.012)	–
Respiratory rate (1/min), median (range)	322	24 (11–50)	124	26 (11–50)	198	24 (11–44)	1.029 (1.004–1.056)	1.06 (0.99–1.14)
Weight (kg), median (range)	328	65 (28–138)	127	62 (36–138)	201	67 (28–124)	0.991 (0.981–1.001)	–
Laboratories values (at admission)
Hemoglobin level (g/L), median (range)	357	137 (71–210)	140	132 (71–186)	217	141 (84–210)	0.98 (0.97–0.99)**	0.98 (0.96–1.01)
Creatinine (g/L), median (range)	358	76 (35–905)	140	78.5 (36–905)	218	74 (35–348)	1.003 (1.001–1.004)**	0.99 (0.98–1.01)
Potassium (mmol/L), median (range)	355	4.1 (3–6.8)	138	4.15 (3–6.8)	217	4 (3–6.3)	1.62 (1.20–2.19)	1.81 (0.78–4.22)
Albumin (g/L), median (range)	174	31 (16–40)	79	30 (16–39)	95	32 (19–40)	0.94 (0.89–0.98)	0.96 (0.85–1.10)
PaCO2 (kPa), median (range)	318	5.7 (2.7–17.5)	123	5.9 (3.9–12.8)	195	5.4 (2.7–17.5)	1.07 (0.98–1.18)	–
pH, median (range)	318	7.41 (6.98–7.63)	123	7.41 (7.18–7.54)	195	7.41 (6.98–7.63)	0.144 (0.014–1.496)	–
Procalcitonin (µg/L), median (range)	184	0.11 (0.02–240)	73	0.18 (0.04–240)	111	0.09 (0.02–26.95)	1.009 (1.001–1.017)	1.02 (1.00–1.03)

Notes: n: number of available data. P-value in bold when <0.05.

* Nonadjusted HR death vs no death.

** P-value in bold when <0.002.

*** Adjusted hazard ratio for the Cox proportional hazard model.

Abbreviations: CI, confidence interval; FEV₁, forced expiratory volume in 1 s; PaCO₂, partial pressure of carbon dioxide.

Figure 2 Kaplan–Meier curve of survival for COPD patients after acute exacerbation after 1 year.

Note: 95%CI is in dashed lines.
Abbreviation: CI, confidence interval.