Project 2, Study 2: Extended Exposure to Low Nicotine Content Cigarettes in Opioid Abusers

The primary overall objective of these studies is to evaluate the effects of extended exposure to cigarettes differing in nicotine content in adults with opioid use disorder using a 3-condition, parallel groups design. After a baseline period in which daily smoking rate and other baseline assessments are completed, participants will be randomly assigned to one of three cigarette conditions (nicotine content: 0.04, 2.4, and 15.8 mg nicotine/gram of tobacco) for the 12-week experimental period. The cigarettes to be used in this study were made under an NIH contract with production being overseen by the Research Triangle Institute (referred to as "Spectrum cigarettes"). NIH currently has approximately 10 million of these cigarettes (of varying types) for research purposes. The cigarettes selected for the study span the range of yields likely to produce the hypothesized effects, as described above. The Spectrum cigarettes are not currently commercially available, although they are similar in many ways to marketed cigarettes (e.g., similar manufacturing, filter, paper, etc.). The primary overall objective of this study is to evaluate the effects of extended exposure to cigarettes differing in nicotine content in male and female adults with opioid use disorder using a 3-condition, parallel groups design. After a baseline period in which daily smoking rate and other baseline assessments are completed, participants will be randomly assigned to one of three cigarette conditions (nicotine content: 0.04 mg, 2.4 mg, and 15.8 mg nicotine/g of tobacco) for the 12-week experimental period. Participants will be seen weekly throughout the 12-week experimental period to obtain research cigarettes. Cigarettes smoked per day will be obtained by participants completing daily Interactive Voice Response (IVR) reports of cigarettes in past 24 hours. This daily data will be used to calculate weekly means, with week-12 means serving as the primary outcome. This same study was conducted in two additional vulnerable populations under a similar protocol, with differences between protocols consisting of data collection specific to that vulnerable population. This included information such as additional assessments of anxiety and depression for individuals with affective disorders or other measures specific to disadvantaged women of reproductive age. In order to explore potential differences across individuals with different vulnerabilities, data from all three studies were combined for analysis. A vulnerable population-by-condition or population-by-condition-by-time interaction term was included in all analyses. In the event that these interaction terms were statistically significant, all pairwise comparisons were conducted using a Bonferroni multiple comparison adjustment.