Table 3.

Hazard ratios of vitiligo development in association with amount and duration of smoking.

	Number	Vitiligo	Person-years	Incidence rate (per 10,000 person-years)	HR(95%C.I)
					Model1	Model2	Model3
Amount of smoking
Never-smoker	14,345,458	16,515	62,819,781.1	2.63	1(ref.)	1(ref.)	1(ref.)
Ex-smoker
smoked <10 cigarettes/day	475,960	472	2,056,674.1	2.29	0.87(0.80,0.96)	1.04(0.95,1.14)	1.03(0.94,1.13)
smoked 10–19 cigarettes/day	1,160,814	1,124	5,173,202.4	2.17	0.83(0.78,0.88)	1.01(0.95,1.08)	1.01(0.95,1.1)
smoked ≥20 cigarettes/day	1,405,910	1,407	6,208,995.1	2.27	0.86(0.82,0.91)	1.01(0.95,1.08)	1.03(0.97,1.10)
Current smoker
smokes <10 cigarettes/day	692,322	538	2,933,516.2	1.83	0.70(0.64,0.76)	0.85(0.78,0.93)	0.86(0.79,0.94)
smokes 10~19 cigarettes/day	2,371,434	1,396	10,335,923.5	1.35	0.51(0.49,0.54)	0.69(0.65,0.73)	0.69(0.65,0.74)
smokes ≥20 cigarettes/day	2,539,743	1,359	11,105,033.4	1.22	0.47(0.44,0.49)	0.60(0.56,0.64)	0.62(0.58,0.66)
Duration of smoking
Never-smoker	14,345,458	16,515	62,819,781.1	2.63	1(ref.)	1(ref.)	1(ref.)
Ex-smoker
smoked for <10 years	708,297	635	3,093,384.6	2.04	0.78(0.72,0.84)	1.02(0.94,1.11)	1.02(0.94,1.11)
smoked for 10–30 years	1,789,335	1,772	7,959,831.9	2.23	0.85(0.81,0.89)	1.04(0.98,1.10)	1.04(0.99,1.11)
smoked for ≥30 years	545,052	596	2,374,378.6	2.51	0.96(0.88,1.04)	0.99(0.90,1.07)	0.98(0.90,1.07)
Current smoker
smokes for <10 years	891,176	521	3,778,089.1	1.38	0.525(0.48,0.57)	0.77(0.71,0.85)	0.791(0.72,0.87)
smokes for 10–30 years	3,424,942	1,868	15,042,614.6	1.24	0.47(0.45,0.50)	0.65 (0.62,0.69)	0.67(0.63,0.70)
smokes for ≥30 years	1,287,381	904	5,553,769.4	1.63	0.62(0.58,0.66)	0.67(0.63,0.72)	0.68(0.63,0.73)

Model 1 Not adjusted.

Model 2 Adjusted by age and sex.

Model 3 Adjusted by age, sex, regular exercise, drinking status, BMI, diabetes mellitus, hypertension, dyslipidemia, history of stroke, and history of myocardial infarction