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Table 3 Cox regression analyses to identify the factors associated with progression-free survival (PFS)

From: Lower starting dose of afatinib for the treatment of metastatic lung adenocarcinoma harboring exon 21 and exon 19 mutations

Variables Univariate analysis Multivariable analysis - model 1 a Multivariable analysis - model 2 a
HR [95% CI] P value HR [95% CI] P value HR [95% CI] P value
Afatinib dose (40 mg daily vs. 30 mg daily) 0.86 [0.58–1.29] 0.4657     
Sex (male vs. female) 1.19 [0.80–1.79] 0.3920     
Age (≥65 vs. < 65) 0.79 [0.53–1.17] 0.2333     
Smoking history (ever smokers vs. never smokers) 1.16 [0.71–1.89] 0.5659     
ECOG (≥2 vs. ≤1) 1.11 [0.67–1.84] 0.6762     
Exon 21 vs. exon 19 b 1.31 [0.89–1.95] 0.1751    1.56 [1.04–2.36] 0.0336
Number of metastatic sites/organs (1–2 vs. ≥3) 1.86 [1.20–2.88] 0.0055 1.83 [1.19–2.84] 0.0065   
Metastatic site/organ on initial diagnosis: (yes vs. no)
 Brain 0.96 [0.62–1.49] 0.8479     
 Lung 0.96 [0.64–1.44] 0.8318     
 Pleura (or with pleural effusion) 1.57 [1.05–2.35] 0.0292    1.77 [1.17–2.69] 0.0075
 Bone 1.52 [1.02–2.27] 0.0385    1.69 [1.13–2.55] 0.0116
 Liver 1.50 [0.89–2.54] 0.1266     
 Adrenal gland 0.96 [0.50–1.84] 0.8955     
 Other site 0.84 [0.34–2.07] 0.7055     
Dose reduction (yes vs. no) 0.56 [0.32–0.98] 0.0407 0.57 [0.33–0.99] 0.0467 0.59 [0.34–1.03] 0.0640
  1. aMultivariable Cox regression models were built using backward variable selection method, keeping only variables with p values less than 0.1. Number of metastatic sites/organs was considered while building model 1, whereas the detailed metastatic sites were considered while building model 2
  2. bThe patient with mutation in both exon 21 and exon 19 was arbitrary classified in to exon 21 group