Table 3.

Correlations (r) between biomarkers and cigarette consumption by variables

When analyzed separately by variables of interest
Total population (n = 700)CYP2A6*1/*1 only (n = 275)CYP2A6 variants only (n = 267)3HC/COT* Quartiles 2-4 (n = 451)Slowest quartile* (n = 151)
CPD
    Expired CO0.320.300.330.280.36
    Plasma nicotine0.310.330.330.300.22
    Plasma COT0.390.400.440.390.33
    Plasma 3HC*0.310.360.310.390.27
Expired CO
    Plasma nicotine0.630.650.610.610.61
    Plasma COT0.600.620.590.590.50
    Plasma 3HC*0.450.520.390.540.44
Total population (n = 700)Males (n = 233)Females (n = 467)Smoke nonmentholated cigarettes (n = 131)Smoke mentholated cigarettes (n = 569)
CPD
    Expired CO0.320.210.380.380.30
    Plasma nicotine0.310.310.310.320.31
    Plasma COT0.390.360.410.370.40
    Plasma 3HC*0.310.21#0.360.360.30
Expired CO
    Plasma nicotine0.630.630.630.650.62
    Plasma COT0.600.630.590.590.61
    Plasma 3HC*0.450.330.500.460.45
Total population (n = 700)Low BMI (<30.0; n = 381)High BMI (≥30.0; n = 316)Younger age (<44.8; n = 349)Older age (>44.8; n = 349)
CPD
    Expired CO0.320.240.380.270.35
    Plasma nicotine0.310.270.340.280.34
    Plasma COT0.390.340.430.360.42
    Plasma 3HC*0.310.290.330.310.32
Expired CO
    Plasma nicotine0.630.610.640.660.59
    Plasma COT0.600.540.650.610.59
    Plasma 3HC*0.450.400.510.540.38

NOTE: Values listed are Pearson's correlation coefficients calculated on log-transformed variables (CPD, expired CO, plasma nicotine, COT, 3HC); all were significant at P < 0.001 with the exception of the value marked as #, which was significant at P < 0.01.

  • *3HC data were available for a subset of the participants only.