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

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

Variables	Univariate analysis		Multivariable analysis - model 1 ^a		Multivariable analysis - model 2 ^a
Variables	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

^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
^bThe patient with mutation in both exon 21 and exon 19 was arbitrary classified in to exon 21 group

ISSN: 1471-2407