Table 3

Results of the multivariate Cox proportional hazards analyses of the predictors of mortality in patients with chronic obstructive pulmonary disease (COPD)

	RR	95% CI	p-value
All deaths
CRQ Total	1.005	0.987–1.022	0.60
Age yrs	1.091	1.037–1.147	<0.001
BMI kg·m⁻²	0.878	0.765–1.008	0.06
Postbronchodilator FEV₁ % pred	0.968	0.949–0.987	0.001
Total lung capacity % pred	0.994	0.974–1.015	0.58
K_CO mmol·min⁻¹·kPa⁻¹·L⁻¹	0.227	0.063–0.811	0.02
COPD deaths
CRQ Total	0.991	0.964–1.019	0.54
Age yrs	1.136	1.035–1.248	0.007
BMI kg·m⁻²	0.699	0.563–0.868	0.001
Postbronchodilator FEV₁ % pred	0.922	0.890–0.955	<0.001
Total lung capacity % pred	0.997	0.960–1.036	0.87
K_CO mmol·min⁻¹·kPa⁻¹·L⁻¹	0.113	0.010–1.275	0.08

Total deaths (n=143); COPD deaths (n=123)
RR: relative risk
CI: confidence interval
CRQ: Chronic Respiratory Disease Questionnaire
BMI: body mass index
FEV₁: forced expiratory volume in one second
% pred: % predicted
K_CO: carbon monoxide transfer coefficient