A similar pattern of results, though slightly weaker, was observed in the total sample of boys and girls, but only after controlling for HC use. This may suggest a link between HC use and smoking topography measures. The stronger relationship found by Strasser [9] and colleagues with total puff volume might be due to both the use of genotype as predictor and the categorical nature of that analysis. In that study of adult smokers, the authors compared mean topography measures among 3 groups (slow, intermediate and normal rate metabolism) of CYP 2A6 genotypes. In the current study, metabolism predicted higher mean puff volume but lower puff duration and smaller number of puffs explaining the lack of relationship of metabolism with total puff volume (the product of mean puff volume by number of puffs). Important differences in smoking histories between adult [10] and adolescent smokers might also have contributed to the different relationships observed. While the samples in the two studies are quite different (i.e., adolescents versus adults), notably, indices of nicotine metabolism (data not shown) and puff volumes found in the current study were comparable to values reported in other adult smokers [20].
