Table 2.

Relationships among biomarkers analyzed in this study

Toenail nicotineToenail cotinineToenail NNALPlasma nicotinePlasma cotininePlasma 3HC
Toenail cotinine
    Pearson correlation coefficient0.43
    P value<0.001
    No. samples105
Toenail NNAL
    Pearson correlation coefficient0.680.69
    P value<0.001<0.001
    No. samples5151
Plasma nicotine
    Pearson correlation coefficient0.390.260.22
    P value<0.0010.0210.252
    No. samples787829
Plasma cotinine
    Pearson correlation coefficient0.540.450.370.86
    P value<0.001<0.0010.050<0.001
    No. samples78782978
Plasma 3HC
    Pearson correlation coefficient0.390.300.240.550.67
    P value<0.0010.0080.220<0.001<0.001
    No. samples7878297878
Urine NNAL
    Pearson correlation coefficient0.420.430.530.350.530.40
    P value<0.001<0.0010.0050.003<0.001<0.001
    No. samples717127707070
  • Abbreviation: 3HC, trans-3′-hydroxycotinine.