Table 6

Factors associated with time to death, predictive Cox model

UnivariateMultivariate predictive
HR95% CIP valuesHR95% CIP values
Predictive variables
 Age1.0010.98 to 1.020.9
 Male gender0.780.50 to 1.230.28
 Zubrod 2–4 vs 0–13.592.22 to 5.80<0.0013.712.14 to 6.45<0.001
 Urgent/emergent vs elective1.510.89 to 2.560.13
 Time from diagnosis to procedure (weeks)11.00 to 1.000.18
 Baseline Borg1.151.07 to 1.25<0.0011.111.01 to 1.210.03
 Baseline utility2.310.45 to 11.830.32
   COPD0.740.38 to 1.440.38
   Cardiovascular1.620.98 to 2.670.06
   Diabetes0.850.49 to 1.450.54
   Second primary1.570.83 to 2.990.17
 Cancer type
   Lung0.930.59 to 1.460.75
   Other malignancies<ref>
 Initial treatment type
   Surgery1.390.74 to 2.610.31.990.99 to 4.020.05
   Chemotherapy2.61.35 to 5.000.0042.931.41 to 6.090.004
   Radiation therapy2.441.13 to to 4.790.11
   No treatment<ref><ref>
 Any prior therapeutic bronchoscopy0.380.14 to 1.040.06
 Indication(s) for therapeutic bronchoscopy
   Tracheoesophageal fistula1.190.37 to 3.800.77
   Haemoptysis0.620.35 to 1.110.11
 Number of bronchopulmonary segments obstructed1.051.01 to 1.100.03
 Location of most proximal obstruction
   Trachea1.580.75 to 3.320.23
   Bilateral mainstem2.110.77 to 5.770.15
   Right mainstem1.110.54 to 2.310.78
   Left mainstem0.780.34 to 1.780.56
   Right bronchus intermedius1.190.50 to 2.800.7
   Lobar only<ref>
 Obstruction type of most proximal location
   Extrinsic2.011.21 to 3.320.012.661.53 to 4.620.001
   Mixed3.311.68 to 6.540.0011.820.82 to 4.030.139
Explanatory variables
 Ventilation type
   Jet ventilation1.590.69 to 3.660.27
   Volume cycled0.610.27 to 1.420.25
 Bronchoscopy type
   Rigid and flexible1.230.53 to 2.830.63
   Flexible only<ref>
 Treatment modalities
   Any laser0.480.24 to 0.950.04
   Electrocautery0.670.40 to 1.100.11
   Argon plasma0.850.54 to 1.330.48
   Cryorecanalisation0.730.41 to 1.310.29
   Microdebrider0.780.46 to 1.320.35
   Rigid ‘coring’0.790.38 to 1.640.52
   Dilation1.420.83 to 2.430.2
 Stent type placed
   Aero1.170.50 to 2.730.71
   Y-Stent0.80.33 to 1.940.63
 Technical success
   Complete or partial0.690.34 to 1.380.3
 Postprocedure treatment
   Chemotherapy0.540.34 to 0.840.01
   Radiation therapy0.860.55 to 1.350.52
Time-varying covariates
 Presence of stent2.471.56 to 3.91<0.001
 Utility0.0020.0003 to 0.011<0.001
 Borg score1.221.14 to 1.31<0.001
 Lower respiratory tract infection2.350.72 to 7.63<0.001
  • Utility range is from 0 to 1. So for a 0.01 unit increase in utility as a time-varying covariate, the HR is 0.002^0.01=0.94. So for each 0.01 increase in utility, the hazard rate of death decreases by 6%. Note that this is exponential, so for a 0.1 increase in utility, the hazard rate of death does not decrease by 60%. Rather it is 0.002^0.1=0.54. So an increase in utility of 0.1 is associated with a 46% decrease in the hazard rate of death.