Predictors of All-Cause Mortality in Patients with Stable COPD: Medical Co-morbid Conditions or High Depressive Symptoms

Figures & data

Table 1.  Characteristics of the total sample of patients with stable COPD

Variable	N	All patients	Survivors	All-cause mortality	p value*
Female Sex (%)	224	48.2	54.5	42.1	ns
Age (y)	224	61.2 (±10.0)	57.7 (±8.9)	65.2 (±9.8)	.000
Partner yes (%)	224	69.6	69.1	70.2	.011
Smoking yes (%)	224	36.6	40.0	33.3	ns
Median f.u. time (y)	224	4.2	4.7	3.1
FEV1 (l)	224	1.1 (±0.5)	1.3 (±0.6)	1.0 (±0.4)	.001
FEV1 (%pred)	224	41.0 (±15.6)	43.2 (±16.3)	37.8 (±14.1)	.012
GOLD stages (%) II/III/IV	224	27.7/44.2/28.1	35.5/38.2/26.4	20.2/50.0/29.8
RV%TLC	222	57.1 (±11.1)	54.7 (±12)	59.4 (±9.8)	.001
BMI (kg/m^2)	224	26.2 (±6.6)	26.5 (±7.0)	25.8 (±6.3)	ns
FFMI (kg/m^2)	212	18.8 (±4.5)	19.9 (±4.9)	17.8 (±3.9)	.001
Wpeak (W)	217	45.6 (±31.2)	57.3 (±34.9)	34.6 (±22.3)	.000
PaO2 (kPa)	213	9.3 (±1.4)	9.4 (±1.4)	9.1 (±1.4)	ns
PaCO2 (kPa)	214	5.4 (±1.3)	5.2 (±0.7)	5.6 (±1.7)	ns
Lactate (mmol/l)	208	1.7 (±1.0)	1.5 (±0.86)	1.8 (±1.1)	ns
VO2peak (ml/min)	217	869 (±374)	981 (±437)	760 (±259)	.000
ISWT (%predicted)	222	213 (±151)	267 (±160)	162 (±122)	.000
Depressive symptoms HADS	203	6.1 (±4.1)	6.5 (±4.2)	5.8 (±4.0)	ns
Depressive symptoms SCL-90	224	28.7 (±10.4)	29.2 (±11.0)	28.2 (±9.9)	ns
Charlson Comorbidity Index	224	0.6 (±0.9)	0.5 (±0.8)	0.8 (±1.0)	.011

Definition of abbreviations: FEV₁ = forced expiratory volume in 1 second; RV = residual volume; TLC = total lung capacity; BMI = body mass index; FFMI = fat-free mass index; Wpeak = maximal workload sustained for at least 30 seconds during symptom limited cycle ergometry; PaO₂ = arterial oxygen tension; PaCO₂ = arterial carbon dioxide tension; VO₂peak = maximal oxygen uptake during symptom limited cycle ergometry; ISWT = incremental shuttle walk test.

*Independent Samples Test.

Table 2.  Frequencies of comorbidities in the sample of patients with stable COPD, classified according to the Charlson Comorbidity Index (CCI)

Comorbidity N (%)*	All patients (N = 224)	Survivors (N = 110)	All Cause Mortality (N = 114)
DM without organ damage	30 (13.4)	12 (10.9)	18 (15.8)
Congestive heart failure	28 (12.5)	7 (6.4)	21 (18.4)
Myocardial infarction	21 (9.4)	10 (9.1)	11 (9.6)
Any tumor	18 (8.0)	7 (6.4)	11 (9.6)
Cerebrovascular disease	13 (5.8)	5 (4.5)	8 (7.0)
Peripheral vascular disease	7 (3.1)	2 (1.8)	5 (4.4)
Connective tissue disease	6 (2.7)	2 (1.8)	4 (3.5)
Mild liver disease	7 (3.1)	3 (2.7)	4 (3.5)
Peptic ulcer disease	3 (1.3)	2 (1.8)	1 (0.9)
Moderate or severe renal disease**	37 (20.7)	12 (10.9)	25 (21.9)

*The comorbidities dementia, hemiplegia, diabetes with organ damage, lymphoma, leukemia, moderate or severe liver disease, metastatic solid tumor and AIDS were not present in this sample.

**N = 178, for 46 patients no data on recent renal function were available.

Table 3.  Predictors of mortality in all patients with stable COPD

	Bivariate			Multivariate*
Variable	B	Hazard ratio	95% CI	B	Hazard ratio	95% CI
Sex	0.30	1.36	0.93–1.97
Age (y)	0.05	1.05	1.03–1.08****	0.04	1.04	1.02–1.07****
Partner^2	0.01	1.01	0.68–1.52
Smoking^3	−0.17	0.84	0.57–1.25
FEV1 (l)	−0.56	0.57	0.38–0.86***	−0.05	0.96	0.57–1.59
RV%TLC (%, n = 216)	0.02	1.02	1.00–1.04**
BMI (kg/m^2)	−0.03	0.98	0.95–1.01
FFMI (kg/m^2, n = 212)	−0.06	0.92	0.89–0.99**	−0.08	0.93	0.88–0.98***
Wpeak (W, n = 217)	−0.02	0.98	0.97–0.99****
PaO2 (kPa, n = 213)	−0.16	0.86	0.74–0.99**
PaCO2 (kPa, n = 214)	0.08	1.08	0.99–1.20
Lactate (mmol/l, n = 208)	0.12	1.11	0.95–1.29
VO2peak (ml/min, n = 217)	−0.00	0.99	0.998–0.999****
ISWT (%predicted, n = 222)	−0.00	1.00	0.994–0.998****	−0.03	0.997	0.995–0.999***
Depressive sympt. HADS (n = 203)	−0.02	0.98	0.93–1.03
Depressive sympt. SCL-90	−0.01	0.99	0.97–1.01
Charlson Comorbidity Index^4	0.28	1.32	0.91–1.92

Definition of abbreviations: FEV₁ = forced expiratory volume in 1 second; RV = residual volume; TLC = total lung ­capacity; BMI = body mass index; FFMI = fat-free mass index; Wpeak = maximal workload sustained for at least 30 s during ­symptom limited cycle ergometry; PaO₂ = arterial oxygen tension; PaCO₂ = arterial carbon dioxide tension; VO₂peak = maximal oxygen uptake during symptom limited cycle ergometry; ISWT = incremental shuttle walk test.

*Cox proportional hazard model backward stepwise (Wald).

**p < 0.05.

***p < 0.01.

****p <0.001.

0 = female, 1 = male.

²0 = living without a partner, 1 = living with a partner.

³0 = never smoked or ex-smoker for ≥1 year, 1 = current smoker or ex-smoker <1 year.

⁴0 = no co-morbidity, 1 = one or more co-morbidities.

Figure 1.  Kaplan Meier survival plots for patients with stable COPD without medical co-morbidities or high depressive symptoms and patients with stable COPD and congestive heart failure.