Table 5.

Urinary levels of [pyridine-D₄]hydroxy acid:total [pyridine-D₄]NNAL ratio by PEITC treatment in stratified analysis, The PEITC Intervention Study 2008–2013

Stratifying variable at baseline (visit 2)	No	Geometric means of [pyridine-D4]hydroxy acid:total [pyridine-D4]NNAL ratio				P for interactionb
		Placebo	PEITC	% difference (95% CI)	P valuea
Age						0.245
< 40	34	0.531	0.515	−3.2 (−12.9, 7.7)	0.559
≥ 40	48	0.408	0.364	−10.8 (−18.3, −2.5)	0.015
Sex						0.606
Men	44	0.474	0.446	−6.0 (−15.1, 4.0)	0.238
Women	38	0.434	0.394	−9.3 (−17.2, −0.7)	0.043
Years of smoking						0.675
≤10	22	0.511	0.465	−9.0 (−21.8, 6.0)	0.240
11–20	30	0.441	0.423	−4.2 (−13.0, 5.4)	0.386
≥ 21	30	0.436	0.385	−11.6 (−22.1, 0.2)	0.065
Total nicotine equivalentsc
< median	40	0.507	0.453	−10.7 (−18.8, −1.7)	0.026	0.544
≥ median	41	0.409	0.381	−6.8 (−15.8, 3.3)	0.186
Total 3′-hydroxycotinine: total cotinine ratioc						0.345
< median	40	0.463	0.438	−5.6 (−14.0, 3.8)	0.243
≥ median	41	0.446	0.395	−11.5 (−19.6, −2.4)	0.018

^a2-sided P values were derived from the mixed models to test PEITC treatment effect within a subgroup by stratifying variable.

^b2-sided P values were derived from the mixed models to test PEITC treatment effect cross group of stratifying variable.

^cOne subject did not provide the 24-hr urine sample at visit 2, thus, were excluded from the analysis.