Candidates for this study were a sample of convenience of male and female adolescent smokers who enrolled in a smoking cessation study between September 1999 and May 2003. Participants were recruited through radio, print, and television advertisements broadly directed at Baltimore-area teenage smokers, with some ethnic-specific channels. Study eligibility required that participants be in general good health and report smoking at least 10 cigarettes per day (CPD) in addition to having a score of at least five on the Fagerstrom Test of Nicotine Dependence (FTND). In this analysis, only teenagers who reported mentholated cigarettes as their usual/preferred brand and who self-identified as African-American or European-American were included.
Adolescents and their parents were required to give written informed assent and consent for participation. All participants were compensated for their time and travel costs. The protocol was approved by the NIH/NIDA Intramural Research Program Institutional Review Board.
Prior to randomization to the treatment condition, participant smoking histories, including age of onset, CPD, and number of prior quit attempts were obtained through both self-report questionnaires and a structured screening interview.
Smoking measures were obtained for each participant in a specialized smoking laboratory during an initial screening visit. The topography unit (Clinical Research Support System, Plowshare Technologies, Baltimore, MD) was placed in a ventilated smoking chamber, and a nurse was present at all times during the session. Participants were asked to smoke a single cigarette of their own usual brand (mean Federal Trade Commission yields for all brands = approximately 1.2 mg nicotine) through a plastic mouthpiece connected to a converter by a plastic tube. The mean puff volume, puff duration, and maximum puff velocity were measured and recorded. Topography measures were obtained by averaging the measures from five representative artifact-free puffs (volumes over 12 mL), as previously reported. cialis canadian pharmacy
HR, systolic blood pressure (SBP), and diastolic (DBP) were obtained through the use of an automated cardiovascular monitor (Datascope, Paramus, NJ). Exhaled CO was measured by a Vita-lograph machine (Lenexa, KS). All physiological measures and CO were measured and recorded before and immediately after smoking.
Baseline characteristics (demographics and smoking history variables) and smoking topography variables were compared using two sample t-tests for continuous variables and Chi-square tests for dichotomous variables. The effect of ethnicity on cardiovascular response to smoking and CO boost was determined using analyses of covariance (ANCOVA). In ANCOVA models, dependent variables were measures assessed after smoking (SBP and DBP, HR, CO). The main effect was ethnicity, and the covariate was the corresponding or CO measure assessed prior to smoking. Associations were considered statistically significant if p<0.05. All analyses were conducted using SAS version 8.1 (SAS Institute, Cary, NC).