Table 2

Predictors of the glucuronidation ratioa: multivariate linear regression models and univariate spearman correlation coefficients

Adjusted r2Independent VariablesbpUnivariate Correlation (p)
    Glucuronidation ratio41African American vs. European American<0.0001−0.49 (<0.0001)
Male vs. female0.536−0.21 (0.04)
Age0.138−0.22 (0.03)
Nicotine equivalentsc0.00020.30 (0.003)
trans-3′-Hydroxycotinine/cotinine ratiod0.0031−0.37 (0.0003)
    Glucuronidation ratio50African American vs. European American0.032−0.35 (0.01)
Male vs. female0.103−0.36 (0.01)
Age0.180−0.20 (0.15)
Nicotine equivalentsc0.0010.27 (0.05)
trans-3′-Hydroxycotinine/cotinine ratiod<0.0001−0.56 (<0.0001)
  • a Glucuronidation ratio = cotinine-N-glucuronide/free cotinine; square-root transformed.

  • b Stepwise selection was used to select variables included in the models presented, although demographic variables (ethnicity, age, and gender) were forced into the model if rejected during selection. Nicotine and its metabolites were measured in 24-h urine.

  • c Nicotine equivalents = sum of urinary total nicotine, total cotinine, and total trans-3′-hydroxycotinine.

  • d trans-3′-Hydroxycotinine/cotinine ratio = total trans-3′-hydroxycotinine/total cotinine; square-root transformed.