Table 4.

Multiple regression analysis for biomarkers (adjusted for creatinine)

CovariatesCoefficent (SE)P
Dependent variable = TNE nmol/mg creatinine (N = 343) R2 = 0.32
 Intercept1.9 (20.0)0.925
 Annual income ≥ 15K−5.1 (7.1)0.470
 Number of years using snuff daily1.3 (0.3)<0.001
 Age when first used snuff0.04 (0.42)0.937
 Dependence score−0.5 (1.0)0.608
 Tins per week5.0 (1.7)0.004
 Mean dips per day−0.2 (2.2)0.945
 Mean duration per dip (minutes)−0.01 (0.20)0.958
 Mean daily dip duration (hours)7.6 (2.4)0.002
 Constituent yield: Free nicotine mg/g wet weight−1.9 (2.2)0.402
Covariatesexp(coeff) (95% CI)P
Dependent variable = total NNAL pmol/mg creatininea (N = 342) R2 = 0.50
 Annual income ≥ 15K0.97 (0.81–1.16)0.724
 Number of years using snuff daily1.02 (1.01–1.03)<0.001
 Age when first used snuff1.00 (0.99–1.01)0.520
 Dependence score1.00 (0.98–1.03)0.939
 Tins per week1.13 (1.08–1.18)<0.001
 Mean dips per day1.05 (0.99–1.11)0.089
 Mean duration per dip (minutes)1.01 (1.00–1.01)0.045
 Mean daily dip duration (hours)1.07 (1.01–1.14)0.027
 Constituent yield: NNK μg/g wet weight1.38 (1.16–1.64)<0.001
 Constituent yield: NNK/free nicotine0.84 (0.50–1.39)0.497
Covariatesexp(coeff) (95% CI)P
Dependent variable = total NNN pmol/mg creatininea (N = 326) R2 = 0.43
 Annual income ≥ 15K0.85 (0.69–1.06)0.156
 Number of years using snuff daily1.02 (1.01–1.03)<0.001
 Age when first used snuff1.01 (1.00–1.02)0.180
 Dependence score1.01 (0.98–1.04)0.473
 Smoked >100 cigarettes in lifetime1.21 (0.99–1.49)0.067
 Tins per week1.12 (1.06–1.18)<0.001
 Mean dips per day1.04 (0.97–1.11)0.301
 Mean duration per dip (minutes)1.01 (1.00–1.01)0.067
 Mean daily dip duration (hours)1.07 (1.00–1.15)0.058
 Constituent yield: NNN μg/g wet weight1.12 (1.05–1.20)0.001
 Constituent yield: NNN/free nicotine0.94 (0.76–1.18)0.614

NOTE: The model for each biomarker includes all the covariates from the univariate analysis that were significant with P < 0.1. For total NNN/creatinine, one subject with NNN >60 was excluded from the analysis.

  • aAnalyzed in the logarithmic scale.