Table 3.

HRs for factors related to relapse within 1 year

Variables	HR (95% CI)
Demographic characteristics
Age (yr)	0.98 (0.97, 1.00)*
Gender
Men	1.00 (reference)
Women	1.33 (0.86, 2.07)
Education level
Middle school or less	1.00 (reference)
High school	1.06 (0.75, 1.49)
University or higher	0.68 (0.49, 0.95)*
Baseline smoking characteristics
Age at smoking onset (yr)	0.98 (0.95, 1.01)
Pack-years	1.00 (1.00, 1.01)
Expired CO concentration (ppm)
<10	1.00 (reference)
10-19	1.58 (1.21, 2.06)**
≥20	1.20 (0.88, 1.63)
Nicotine dependence (score)
0-3	1.00 (reference)
4-6	0.93 (0.69, 1.25)
7-10	0.97 (0.70, 1.35)
Motivational characteristics (score)
Importance of quitting	1.09 (1.02, 1.17)*
Confidence in quitting	0.93 (0.87, 0.99)*
Readiness to quit	1.07 (1.00, 1.14)*
Intervention methods
No. of counseling sessions
≤5	1.00 (0.75, 0.83)
6-8	0.32 (0.24, 0.42)***
≥9	0.23 (0.17, 0.32)***
NRT
No use	1.00 (reference)
Use	1.91 (1.43, 2.55)***
Varenicline or bupropion
No use	1.00 (reference)
Use	1.69 (0.80, 3.60)

HR, hazard ratio; CI, confidence interval; NRT, nicotine replacement therapy.

^*p<0.05,

^**p<0.01,

^***p<0.001.