Table 5.
Multivariable Survival Analysis
| Variable | Multivariable Cox Regression 1* | Multivariable Cox Regression 2$ | ||||
|---|---|---|---|---|---|---|
| H.R. | 95% CI | Wald test P value | H.R. | 95% CI | Wald test P value | |
| Gender | 0.002 | 0.002 | ||||
| Female | 1.00 | 1.00 | ||||
| Male | 1.70 | 1.21 – 2.39 | 1.70 | 1.21 – 2.38 | ||
| Smoking status | 0.055 | 0.09 | ||||
| Never smoker | 1.00 | 1.00 | ||||
| Ever smoker | 1.64 | 0.99 – 2.71 | 1.60 | 0.93 – 2.76 | ||
| ECOG PS | 0.01 | 0.01 | ||||
| 0 | 1.00 | 1.00 | ||||
| 1 | 1.32 | 0.90 – 1.92 | 1.32 | 0.91 – 1.92 | ||
| 2+ | 2.09 | 1.28 – 3.42 | 2.09 | 1.28 – 3.42 | ||
| Stage | 0.36 | 0.36 | ||||
| I | 1.00 | 1.00 | ||||
| II | 0.78 | 0.32 – 1.90 | 0.78 | 0.32 – 1.89 | ||
| III | 1.42 | 0.74 – 2.74 | 1.42 | 0.74 – 2.73 | ||
| IV | 1.21 | 0.65 – 2.28 | 1.21 | 0.64 – 2.28 | ||
| Bone Metastases | 0.03 | 0.03 | ||||
| No | 1.00 | 1.00 | ||||
| Yes | 1.50 | 1.04 – 2.16 | 1.49 | 1.04 – 2.15 | ||
| Age-weighted Comorbidity Index | 1.16 | 1.06 – 1.26 | 0.001 | 1.16 | 1.06 – 1.26 | 0.001 |
| EGFR Mutation (any) | 0.85 | |||||
| Positive | 1.00 | |||||
| Negative | 1.06 | 0.59 – 1.92 | ||||
*
Model 1: Best model by backward elimination based on 293 patients with data on 10 candidate variables selected by univariate significance p ≤ 0.10 (see Table 4). Stage was included in the model as an established prognostic factor, regardless of significance.
$
Model 2: EGFR mutation was added to Model 1. Clearly, it was not an independent prognostic factor due to strong collinearity with both smoking status and gender (see Table 2). The significance of smoking status was modified by the presence of EGFR mutation in the model.
HR = Hazard Ratio, CI = Confidence Interval