Table 2

 Predictors of mortality: univariate analysis

Hazard ratio(crude)95% CIp value
BMI, body mass index; FEV1, forced expiratory volume in 1 second; FVC, forced vital capacity; Pao2, Paco2, arterial oxygen and carbon dioxide tensions; LTOT, long term oxygen therapy.
Group A, no acute exacerbations of COPD; group B, 1–2 acute exacerbations of COPD (emergency visits or hospital admissions); group C, ⩾3 acute exacerbations of COPD.
Age (years)<0.001
    <65
    65–741.760.88 to 3.52
    ⩾755.262.70 to 10.24
Current smoking0.970.63 to 1.480.873
Cumulative smoking (pack years)1.000.99 to 1.010.973
Co-morbidity index1.431.28 to 1.60<0.001
Charlson index0.002
    01.00
    11.320.84 to 2.07
    ⩾22.201.41 to 3.43
BMI (kg/m2)0.940.89 to 0.990.034
Postbronchodilator FEV1 (% predicted)0.960.94 to 0.98<0.001
GOLD stage<0.001
    I1.00
    II3.400.81 to 14.21
    III5.341.29 to 22.07
    IV8.342.01 to 34.55
FVC (% predicted)0.980.97 to 0.990.009
Pao2/Fio20.990.98 to 0.99<0.001
Paco2 (kPa)1.051.04 to 1.09<0.001
LTOT3.422.36 to 4.95<0.001
Acute exacerbation groups<0.001
    Group A1.00
    Group B2.201.45 to 3.33
    Group C4.302.62 to 7.02