Table 2.

Correlations and percent difference in cigarette consumption and biomarkers while smoking usual brand of cigarettes on two occasions

Correlation coefficient (r)P% Difference (95% confidence interval)
Cigarettes per day0.91<0.0010.8 (−8.8 to 10.4)
Baseline plasma nicotine (ng/mL)0.550.03434.5 (−46 to 115)
Baseline plasma cotinine (ng/mL)0.81<0.00110.9 (−6.0 to 27.9)
Baseline COHb (%)0.91<0.00114.7 (−0.1 to 29.5)
Plasma nicotine boost (ng/mL)0.460.088.4 (−25.2 to 42.0)
Free NNAL (pmol/mg creat)0.83<0.001−15.5 (−34.4 to 3.4)
Total NNAL (pmol/mg creat)0.92<0.001−12.7 (−30.7 to 5.2)
1-Hydroxypyrene (pmol/mg creat)0.780.00112.3 (−23.4 to 48.0)
Sum 1- and 2-naphthols (pmol/mg creat)0.400.1516.9 (−22.4 to 56.1)
Sum of isomeric hydroxyphenanthrenes (pmol/mg creat)0.090.7424.9 (−30.8 to 80.5)
Sum of isomeric hydroxyfluorenes (pmol/mg creat)0.210.4517.4 (−35.6 to 70.5)