Table 3.

Comparison of the classification of smoking status based on five biomarkers.

Urinary Biomarkers	Cases	Cotinine		Nicotine		Nornicotine		3-OH Cotinine		Anabasine
		Positive	Negative	Positive	Negative	Positive	Negative	Positive	Negative	Positive	Negative
		(3682)	(16,192)	(3460)	(16,414)	(3567)	(16,440)	(3574)	(16,566)	(3566)	(17,250)
Cotinine	Positive			3437	245	3550	113	3519	163	2641	1041
	Negative			23	15,172	17	15,178	55	15,140	925	14,270
	κ			0.954	(0.948–0.959)	0.978	(0.974–0.982)	0.963	(0.958–0.968)	0.664	(0.651–0.678)
Nicotine	Positive	3437	23			3434	26	3308	152	2624	836
	Negative	245	16,169			133	16,281	266	16,148	942	15,472
	κ	0.954	(0.948–0.959)			0.973	(0.968–0.977)	0.968	(0.964–0.973)	0.693	(0.679–0.706)
Nornicotine	Positive	3550	17	3434	133			3417	150	2636	931
	Negative	132	16,308	26	16,414			157	16,283	930	15,510
	κ	0.978	(0.974–0.982)	0.973	(0.968–0.977)			0.948	(0.942–0.953)	0.683	(0.669–0.696)
3-OH cotinine	Positive	3519	55	3308	266	3417	157			2562	1012
	Negative	163	16,403	152	16,414	150	16,416			1004	15,562
	κ	0.963	(0.958–0.968)	0.968	(0.964–0.973)	0.948	(0.942–0.953)			0.657	(0.643–0.671)
Anabasine	Positive	2641	925	2624	942	2636	930	2562	1004
	Negative	1041	16,209	836	16,414	931	16,319	1012	16,238
	κ	0.664	(0.651–0.678)	0.693	(0.679–0.706)	0.683	(0.669–0.696)	0.657	(0.643–0.671)

3-OH cotinine, trans-3′-hydroxycotinine; κ, Cohen’s kappa. Furthermore, 20 ng/mL for nicotine and cotinine, 50 ng/mL for 3-OH cotinine, and 2 ng/mL for nornicotine and anabasine are the cut-off values of five biomarkers for distinguishing between current smokers and non-current smokers.