Table 2—

Multivariate Cox proportional hazard model for survival

CovariateRR crude95% CIRR adjusted95% CIp‐value
Age yr1.0401.025–1.0551.0331.015–1.0510.0002
BMI kg·m−20.9270.900–0.9540.9450.913–0.9790.0016
Smoking 0/11.3140.916–1.8841.0070.669–1.5170.9726
FEV1 %0.9860.977–0.9950.9940.982–1.0060.3046
Pa,O2 kPa0.8430.780–0.9110.9250.838–1.0210.1228
Pa,CO2 kPa1.1871.050–1.3421.0030.849–1.1870.9691
Sex 0/10.7000.529–0.9260.8450.608–1.1730.3140
Inhaled steroids0.5470.426–0.7031.1590.614–2.1880.649
Oral steroids
No1.000reference
5 mg2.3540.937–5.9142.2790.902–5.7620.082
5 mg inhaled steroids1.0780.577–2.0131.0830.564–2.0830.647
10 mg3.2961.757–6.1832.3401.235–4.4350.009
10 mg inhaled steroids1.6360.910–2.9401.6380.908–2.9550.810
15 mg5.9893.027–11.854.0311.994–8.1490.000
15 mg inhaled steroids1.9501.00–3.8041.6160.817–3.1960.167
  • Data presented as relative risk (RR) or 95% confidence interval (CI)

  • BMI: body mass index

  • FEV1 forced expiratory volume in one second

  • Pa,O2: arterial oxygen tension

  • Pa,CO2: arterial carbon dioxide tension

  • 0=no, 1=yes

  • 0=males, 1=females

  • interaction with inhaled steroids 0=no, 1=yes.