Table 3

 Prognostic value of frequency of acute exacerbations of COPD (AECOPD) adjusted by confounders

Hazard ratio(adjusted)95% CIp value
AECOPD, acute exacerbations of COPD; FEV1, forced expiratory volume in 1 second; Pao2, arterial oxygen tension; Fio2, fractional inspired oxygen; 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.
AECOPD adjusted by age
    Age (years)<0.001
        <65Reference–
        65–741.620.80 to 3.25
        ⩾754.522.31 to 8.83
    AECOPD groups<0.001
        Group AReference–
        Group B1.931.27 to 2.93
        Group C3.642.22 to 5.98
AECOPD adjusted by FEV1%
    FEV1% (predicted)0.990.97 to 0.990.028
    AECOPD groups<0.001
        Group AReference–
        Group B2.081.33 to 3.25
        Group C3.451.99 to 5.99
AECOPD adjusted by Pao2/Fio2
    Pao2/Fio20.990.990 to 0.997<0.001
    AECOPD groups<0.001
        Group AReference–
        Group B2.121.37 to 3.29
        Group C3.692.18 to 6.25
AECOPD adjusted by LTOT
    LTOT2.721.84 to 4.02<0.001
    AECOPD groups
        Group AReference–<0.001
        Group B1.741.14 to 2.67
        Group C2.921.74 to 4.88