Table 2

Univariate and logistic regression analyses of risk factors for death at 30 days in patients hospitalised for acute exacerbation of chronic obstructive pulmonary disease

Variable	Univariate analysis			Multivariate logistic regression
Variable	OR	p Value	95% CI	OR	p Value	95% CI
Age, years	1.032	0.171	0.99 to 1.08
BMI, kg/m²	0.925	0.035	0.86 to 0.99	0.905	0.029	0.83 to 0.99
Lung function
FEV₁, litres	0.504	0.392	0.11 to 2.42
% predicted FEV₁, %	0.998	0.923	0.97 to 1.03
FEV₁/FVC, %	1.0	0.998	0.96 to 1.04
PaCO₂, mm Hg	1.049	<0.0001	1.03 to 1.07	1.041	0.002	1.02 to 1.07
PaO₂, mm Hg	0.996	0.683	0.98 to 1.02
CRP, mg/l	1.05	0.949	0.99 to 1.07
Clinical scores
BAP65, increment by 1	1.665	0.065	0.97 to 2.86
CURB65, increment by 1	2.171	<0.0001	1.42 to 3.32	1.684	0.075	0.95 to 2.98
Past medical history
Cardiovascular disease	0.701	0.504	0.25 to 1.99
Cerebral vascular disease	1.990	0.248	0.62 to 6.40
Malignancy	0.466	0.467	0.06 to 3.64
Biochemical markers of cardiac dysfunction
NT-proBNP >220 pmol/l	9.034	<0.0001	3.11 to 26.25	7.455	0.004	1.92 to 28.90
NT-proBNP >220 pmol/l	9.034	<0.0001	3.11 to 26.25	9.241^*	0.001	2.58 to 33.05
Troponin T >0.03 μg/l	6.333	<0.0001	2.43 to 16.50	2.468	0.138	0.75 to 8.15
Troponin T >0.03 μg/l	6.333	<0.0001	2.43 to 16.50	5.115^†	0.003	1.73 to 15.15

Multivariate logistic regression was performed only on risk factors significant in univariate analyses (BMI, pco₂, CURB65 score, high NT-proBNP and high troponin T). Results for elevated NT-proBNP and troponin T are presented before and after adjustments for each other. ORs refer to the change in odds of mortality at 30 days associated with an increase in the predictor variables by one of the respective units.
↵* Analyses include all other variables in the multivariate model except elevated troponin T.
↵† Analyses include all other variables in the multivariate model except elevated NT-proBNP.
BMI, body mass index; CRP, C-reactive protein; FEV₁, forced expiratory volume in 1 s; FVC, forced vital capacity; NT-proBNP, N-terminal pro-brain natriuretic peptide.