Urinary cotinine and cotinine + trans-3'-hydroxycotinine (TNE-2) cut-points for distinguishing tobacco use from non-use in the United States: PATH Study (2013-2014).

BACKGROUND Determine the overall, sex-, and racially/ethnically-appropriate population-level cotinine and total nicotine equivalents (TNE-2, the molar sum of the two major nicotine metabolites) cut-points to distinguish tobacco users from non-users across multiple definitions of use (e.g., exclusive vs. polytobacco, and daily vs. non-daily). METHODS Using Wave 1 (2013-2014) of the U.S. Population Assessment of Tobacco and Health (PATH) Study, we conducted weighted Receiver Operating Curve (ROC) analysis to determine the optimal urinary cotinine and TNE-2 cut-points, stratified by sex and race/ethnicity. RESULTS For past 30-day exclusive cigarette users, the cotinine cut-point that distinguished them from non-users was 40.5 ng/mL, with considerable variation by sex (male: 22.2 ng/mL; female: 43.1 ng/mL) and between racial/ethnic groups (non-Hispanic other: 5.2 ng/mL; non-Hispanic black: 297.0 ng/mL). A similar, but attenuated, pattern emerged when assessing polytobacco cigarette users (overall cut-point= 39.1 ng/mL, range= 5.5 ng/mL- 80.4 ng/mL) and any tobacco users (overall cut-point= 39.1 ng/mL, range= 4.8 ng/mL- 40.0 ng/mL). Using TNE-2, which is less impacted by racial differences in nicotine metabolism, produced a comparable pattern of results although reduced the range magnitude. CONCLUSIONS Due to similar frequency of cigarette use among polytobacco users, overall cut-points for exclusive cigarette use were not substantially different from cut-points that included polytobacco cigarette use or any tobacco use. Results revealed important differences in sex and race/ethnicity appropriate cut-points when evaluating tobacco use status and established novel urinary TNE-2 cut-points. IMPACT These cut-points may be used for biochemical verification of self-reported tobacco use in epidemiologic studies and clinical trials.