Table 4.

Outcomes of the two-category models for inferring smoking history (years of cessation time) in former smokers from blood based on 13 CpGs

	Former < 5 year versus Former ≥ 5 year cessation time			Former < 10 year versus Former ≥ 10 year cessation time			Former < 15 year versus Former ≥ 15 year cessation time
	Model building data set (N = 1332)		External validation	Model building data set (N = 1332)		External validation	Model building data set (N = 1332)		External validation
	Model building	Fivefold cross-validation	KORA (N = 652)	Model building	Fivefold cross-validation	KORA (N = 652)	Model building	Fivefold cross-validation	KORA (N = 652)
Accuracya (95% CI) ± SD	0.725 (0.700, 0.749)	0.715 ± 0.020	0.830 (0.799, 0.858)	0.730 (0.705, 0.753)	0.721 ± 0.029	0.799 (0.766, 0.829)	0.732 (0.707, 0.756)	0.718 ± 0.016	0.759
Specificity	0.715	0.691 ± 0.090	0.494	0.694	0.682 ± 0.063	0.471	0.663	0.644 ± 0.033	0.449
Sensitivity	0.727	0.718 ± 0.026	0.879	0.740	0.733 ± 0.026	0.900	0.767	0.756 ± 0.015	0.902
AUC	0.793	0.774 ± 0.024	0.760	0.778	0.766 ± 0.033	0.764	0.779	0.767 ± 0.020	0.754

Cross-validation analysis results are presented as mean ± standard deviation

AUC Area under the curve

^aProportion accurately inferred smoking habits, 95% confidence interval (CI)