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

Geometric means of [pyridine-D4]hydroxy acid:total [pyridine-D4]NNAL ratio
Stratifying variable at baseline (visit 2)NPlaceboPEITC% Difference (95% CI)P valueaP for interactionb
Age, y
 <40340.5310.515−3.2 (−12.9–7.7)0.5590.245
 ≥40480.4080.364−10.8 (−18.3−2.5)0.015
Sex
 Men440.4740.446−6.0 (−15.1–4.0)0.2380.606
 Women380.4340.394−9.3 (−17.2−0.7)0.043
Years of smoking
 ≤10220.5110.465−9.0 (−21.8–6.0)0.240
 11–20300.4410.423−4.2 (−13.0–5.4)0.3860.675
 ≥21300.4360.385−11.6 (−22.1–0.2)0.065
Total nicotine equivalentsc
 <Median400.5070.453−10.7 (−18.8−1.7)0.0260.544
 ≥Median410.4090.381−6.8 (−15.8–3.3)0.186
Total 3′-hydroxycotinine: total cotinine ratioc
 <Median400.4630.438−5.6 (−14.0–3.8)0.2430.345
 ≥Median410.4460.395−11.5 (−19.6−2.4)0.018
  • aTwo-sided P values were derived from the mixed models to test PEITC treatment effect within a subgroup by stratifying variable.

  • bTwo-sided P values were derived from the mixed models to test PEITC treatment effect across group of stratifying variable.

  • cOne subject did not provide the 24-hour urine sample at visit 2, and thus was excluded from the analysis.