Table 2.

Comparisons of pure tone audiometry threshold according to smoking status after adjusting for confounding variables

Frequency	Non-smoker * (n = 2,270)	Ex-smoker * (n = 2,680)	Current smoker * (n = 3,593)	p value †	Post-hoc comparison
1 kHz	15.9 (15.47–16.37)	15.9 (15.51–16.34)	16.5 (16.10–16.83)	0.098	-
2 kHz	18.8 (18.24–19.35)	18.6 (18.04–19.07)	19.6 (19.11–20.01)	0.012	a,b < c
3 kHz	26.5 (25.81–27.22)	27.0 (26.36–27.67)	28.0 (27.43–28.58)	0.005	a,b < c
4 kHz	32.1 (31.30–32.80)	32.5 (31.84–33.24)	33.9 (33.34–34.55)	<0.001	a,b < c

mean (95% confidence interval), dBHL.

^* a: Non-smoker, b: Ex-smoker, c: Current smoker.

^†p-value was calculated by ANCOVA and adjusted for age, working period, noise level, body mass index, mean arterial pressure, fasting blood glucose, total cholesterol, triglyceride, HDL cholesterol, hemoglobin.