Table 3– Significant factors related to chronic obstructive pulmonary disease exacerbation in the multivariable models
VariablesPrescription definitionAdmission definition
Hazard ratio (95% CI)p-valueHazard ratio (95% CI)p-value
Factors related to exacerbation-free survival#
 BMI 1 kg·m−2 increase0.93 (0.87–0.99)0.030.86 (0.76–0.96)0.006
 SGRQ total score 4 points increase1.12 (1.06–1.19)<0.0011.19 (1.08–1.30)<0.001
Factor relating to exacerbation frequency
 BMI 1 kg·m−2 increase0.95 (0.90–0.99)0.030.87 (0.79–0.95)0.004
 SGRQ total score 4 points increase1.09 (1.05–1.14)<0.0011.11 (1.03–1.20)0.008
 FEV1 % predicted 10% increase0.89 (0.81–0.97)0.008
 Haemoglobin 1 g·dL−1 increase0.84 (0.76–0.93)0.001
Factors related to recurrent exacerbation+
 Age 10-year increase1.57 (1.00–2.46)0.049
 BMI 1 kg·m−2 increase0.88 (0.80–0.98)0.02
 SGRQ total score 4 points increase1.07 (1.03–1.11)<0.0011.14 (1.04–1.24)0.005
 Haemoglobin 1 g·dL−1 increase0.87 (0.78–0.97)0.02
  • Complete data tables including all variables and univariate analyses are shown in the online supplementary material. BMI: body mass index; SGRQ: St George’s Respiratory Questionnaire; FEV1: forced expiratory volume in 1 s. #: Cox proportional hazards model; : Poisson regression model; +: Prentice, Williams and Peterson total time model.