Biochemically confirmed 7-day point prevalence abstinence was assessed at end-of-treatment (8 weeks post-quit). All of participants’ self-reports of abstinence during study visits were confirmed by an expired CO (abstinence = CO < 10 ppm). Follow-up telephone calls permitted the determination of time of relapse via timeline follow-up assessment (19, 20) up to 90 days after the quit date. Relapse was defined as smoking for 7 consecutive days.
