Predictors of Enrollment and Adherence in a Randomized Tobacco Cessation Clinical Trial.

Background: New therapeutic cessation approaches are being tested in clinical trials to engage and retain people who smoke. Our team is conducting a pragmatic randomized clinical trial (RCT) to evaluate a new treatment for tobacco dependence, but enrolling participants and ensuring adherence has been more challenging than in previous trials.

Objective: To determine the predictors of enrollment and adherence in the RCT.

Design: A secondary analysis of data from a tobacco cessation RCT.

Methods: Data was collected during a two-group RCT testing the efficacy of an integrative guided imagery vs behavioral treatment, with both conditions involving six weekly, hour-long sessions over 9 weeks.

Results: Of the 1074 randomized participants, 803 (74.8%) enrolled (completed the first session), and 631 (78.6%) of those were adherent (attended all scheduled sessions). Variables associated with enrollment included age (adjusted odds ratio [AOR], 1.01; 95% CI, 1.0003-1.02; = 0.04) and state of residence (West Virginia vs New York (NY), AOR, 0.66; 95% CI, 0.46-0.94; = 0.02), with older participants and those from NY more likely to enroll. Variables associated with adherence included race (Black vs White) (AOR, 2.09; 95% CI, 1.05-4.16; = 0.04), higher education (at least some college vs high school or less) (AOR, 2.27; 95% CI, 1.58-3.26; < 0.0001), marital status (all others vs single/never married) (AOR, 1.66; 95% CI, 1.11-2.48; = 0.01), and state of residence (Arizona vs NY) (AOR, 0.52; 95% CI, 0.34-0.78; = 0.002). Within Arizona, older age increased enrollment, while higher education and marriage improved adherence. Within NY, higher education was associated with both increased enrollment and adherence, while higher number of household smokers, and not reporting substance use were associated with increased adherence.

Conclusion: Enrolling and retaining people who smoke in cessation trials requires novel strategies. Identifying predictors of enrollment and adherence offers valuable insights for overcoming barriers in future tobacco cessation RCTs.