Table 1.

Sensitivity to Detect Smoking and Specificity for Verifying Abstinence in All Subjects, by Carbon Monoxide (CO) Cutoff Level (i.e., Below Which Designates Abstinence)

CO cutoff (ppm)	Sensitivity	Specificity	Sensitivity + specificity
3	0.948	0.542	1.490
4	0.885	0.757	1.642
5	0.826	0.873	1.699
6	0.769	0.911	1.680
7	0.710	0.942	1.652
8	0.658	0.955	1.613
9	0.602	0.967	1.569
10	0.560	0.979	1.539