Table 1

CYP2A6 activity, measured by urinary caffeine metabolite ratio by subject characteristics, among controls

17U/17X
nMeanMedianPaPb
All control subjects3332.031.63
Sex
 Males2171.981.57
 Females1162.121.760.410.11
Race
 Caucasian2971.961.66
 African-American362.601.530.700.76
Age
 <40211.731.42
 40–49241.731.38
 50–59772.041.56
 60–691252.031.59
 ≥70862.161.910.050.09
Current smoker
 No2892.081.66
 Yes441.691.470.360.36
Cigarettes per dayc
 1–19531.971.42
 20622.071.55
 21–80651.991.620.550.69
  • a For sex, race, and current smoking, P is from Wilcoxon rank sum test for comparison of two groups; for age and number of cigarettes per day, P is from nonparametric trend test for differences across groups.

  • b P from linear regression of natural log of 17U:17X with all covariates shown.

  • c Among 271 current or former smokers reporting number of cigarettes smoked per day.