Relationships Between Smoking Behaviors and Cotinine Levels Among Two American Indian Populations With Distinct Smoking Patterns

Introduction: Smoking prevalence, cigarettes per day (CPD), and lung cancer incidence differ between Northern Plains (NP) and Southwest (SW) American Indian populations. We used cotinine as a biomarker of tobacco smoke exposure to biochemically characterize NP and SW smokers and nonsmokers and to investigate factors associated with variation in tobacco exposure. Methods: American Indians (N = 636) were recruited from two different tribal populations (NP and SW) as part of a study conducted as part of the Collaborative to Improve Native Cancer Outcomes P50 project. For each participant, a questionnaire assessed smoking status, CPD, second-hand smoke exposure, and traditional ceremonial tobacco use; plasma and/or salivary cotinine was measured. Results: Cotinine levels were (mean +/- 95% confidence interval [CI]) 81.6 +/- 14.1 and 21.3 +/- 7.3 ng/ml among NP smokers and non-mokers, respectively, and 44.8 +/- 14.4 and 9.8 +/- 5.8 ng/ml among SW smokers and nonsmokers, respectively. Cotinine levels correlated with CPD in both populations (p < .0001). Cotinine >= 15 ng/ml was measured in 73.4% of NP smokers and 47.8% of SW smokers and in 19.0% of NP nonsmokers and 10.9% of SW nonsmokers. Ceremonial traditional tobacco use was associated with higher cotinine among NP smokers only (p = 0.004). Second-hand smoke exposure was associated with higher cotinine among NP non-smokers (P < 0.02). More second-hand smoke exposure was associated with smoking more CPD in both populations (p = 0.03-0.29). Linear regression modeling mirrored these findings. Conclusions: High prevalence of smoking in the Northern Plains and high cotinine levels among nonsmokers in both regions highlights the tribal populations' risk for tobacco-related disease.