Table 3:

Cox proportional hazards regression analysis to predict chronic postoperative pain during the first 36 months after video-assisted thoracoscopic surgery for lung cancer resection

Variables	Hazard ratio (95% CI)	P-value
Adjuvant chemotherapy within 3 months after surgery	1.62 (1.16–2.28)	0.005
Age (years)	1.00 (0.99–1.01)	0.851
Female (versus male)	1.24 (0.99–1.54)	0.058
Body mass index (kg/m²)	1.03 (1.00–1.07)	0.084
Pathological staging (versus stage I)
Stage II or more	1.05 (0.75–1.48)	0.765
Operation time (h)	1.12 (1.00–1.25)	0.046
Operation type (versus pneumonectomy or lobectomy)
Segmentectomy	0.75 (0.48–1.15)	0.183
Wedge resection	1.08 (0.73–1.61)	0.688
Intraoperative analgesia (versus none)
Intercostal nerve blockade	0.71 (0.52–0.96)	0.027
Percutaneous bupivacaine injection	1.14 (0.81–1.62)	0.449
NRS at first postoperative outpatient visit	1.42 (1.36–1.49)	<0.001
Postoperative radiotherapy	0.99 (0.68–1.45)	0.975
Year of surgery (versus 2007)
2008	0.74 (0.31–1.76)	0.496
2009	0.42 (0.17–1.02)	0.054
2010	0.55 (0.25–1.20)	0.132
2011	0.93 (0.47–1.84)	0.825
2012	0.57 (0.28–1.16)	0.118
2013	0.45 (0.22–0.91)	0.027
2014	0.57 (0.28–1.12)	0.103
2015	0.51 (0.25–1.01)	0.052
2016	0.40 (0.20–0.81)	0.011

CI: confidence interval; NRS, numeric rating scale.