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Table 4 Cox regression analyses to identify the factors associated with overall survival (OS)

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) 1.14 [0.70–1.84] 0.5986     
Sex (male vs. female) 1.97 [1.22–3.20] 0.0058 1.97 [1.21–3.22] 0.0066   
Age (≥65 vs. < 65) 0.93 [0.58–1.51] 0.7729     
Smoking history (ever smokers vs. never smokers) 1.90 [1.10–3.29] 0.0210    2.37 [1.35–4.17] 0.0028
ECOG (≥2 vs. ≤1) 2.46 [1.46–4.15] 0.0007 2.28 [1.35–3.85] 0.0021 3.00 [1.74–5.15] < 0.0001
Exon 21 vs. exon 19 b 0.95 [0.59–1.54] 0.8334     
Number of metastatic sites/organs (1–2 vs. ≥3) 1.6 [0.96–2.67] 0.0690 1.61 [0.96–2.68] 0.0709   
Metastatic site/organ on initial diagnosis: (yes vs. no)
 Brain 1.54 [0.93–2.55] 0.0967     
 Lung 1.08 [0.66–1.76] 0.7713     
 Pleura (or with pleural effusion) 1.32 [0.82–2.12] 0.2584     
 Bone 1.64 [0.99–2.70] 0.0532    1.73 [1.04–2.87] 0.0341
 Liver 1.28 [0.68–2.39] 0.4395     
 Adrenal gland 0.45 [0.16–1.25] 0.1264    0.33 [0.12–0.92] 0.0338
 Other site 1.09 [0.40–3.01] 0.8668     
Dose reduction (yes vs. no) 1.08 [0.61–1.92] 0.7903     
  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