Biomarkers of Nicotine and Tobacco Carcinogen Exposure in Socioeconomically Disadvantaged Black Adults Receiving a Brief Smoking Reduction Intervention.

Background: Retrospective reporting of cigarette use can impact the accuracy of outcomes in tobacco treatment trials. The inclusion of objective measures of smoking, like biomarkers of nicotine and tobacco exposure, is recommended. Most trials examining biomarkers after a behavioral intervention have included predominantly White adults enrolled in cessation, versus reduction, trials. The current study examined biomarkers of nicotine and tobacco exposure within a harm reduction trial in Black adults who smoke (AWS).

Methods: Non-treatment-seeking socioeconomically disadvantaged Black AWS (N=65) were randomized to a treatment-as-usual control or enhanced care (EC) single-session intervention aimed to reduce their smoking. Biospecimens were collected at baseline and 1-month post-treatment to measure objective markers of nicotine and smoke exposure, including expired carbon monoxide, urinary metabolites of nicotine (cotinine and trans-3'-hydroxycotinine), and urinary tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL).

Results: Those in the EC condition self-reported a significant reduction in smoking at follow-up (p <.01), but there were no concomitant decreases across biomarkers (all ps >.05). Exploratory analyses in participants who reported at least 50% smoking reductions or reduced daily cigarette intake by at least three cigarettes at follow-up compared to baseline revealed nonsignificant changes across all biomarkers (all ps >.05).

Conclusions: Self-reported smoking reductions were not biochemically verified across measures. It is possible that compensatory behaviors when reducing smoking (e.g., deeper inhalations) or underreporting of smoking contributed to this discrepancy.

Impact: Partial smoking reduction does not appear to reduce biomarkers of carcinogen exposure and may not be an effective strategy to narrow tobacco-related health disparities in Black AWS.