Extended Self-Help for Smoking Cessation: A Randomized Controlled Trial.

<bold>Introduction: </bold>Far too few smokers receive recommended interventions at their healthcare visits, highlighting the importance of identifying effective, low-cost smoking interventions that can be readily delivered. Self-help interventions (e.g., written materials) would meet this need, but they have shown low efficacy. The purpose of this RCT was to determine the efficacy of a self-help intervention with increased duration and intensity.<bold>Design: </bold>Randomized parallel trial design involving enrollment between April 2010 and August 2011 with follow-up data for 24 months.<bold>Setting/participants: </bold>U.S. national sample of daily smokers (N=1,874).<bold>Intervention: </bold>Participants were randomized to one of three arms of a parallel trial design: Traditional Self-Help (TSH, n=638), Standard Repeated Mailings (SRM, n=614), or Intensive Repeated Mailings (IRM, n=622). TSH received an existing self-help booklet for quitting smoking. SRM received eight different cessation booklets mailed over a 12-month period. IRM received monthly mailings of ten booklets and additional material designed to enhance social support over 18 months.<bold>Main Outcome Measures: </bold>The primary outcome was 7-day point-prevalence abstinence collected at 6, 12, 18, and 24 months.<bold>Results: </bold>Data were analyzed between 2013 and 2015. A dose-response effect was found across all four follow-up points. For example, by 24 months, IRM produced the highest abstinence rate (30.0%), followed by SRM (24.4%) and TSH (18.9%). The difference in 24-month abstinence rates between IRM and TSH was 11.0% (95% CI=5.7%, 16.3%). Cost analyses indicated that, compared with TSH, the incremental cost per quitter who received SRM and IRM was $560 and $361, respectively.<bold>Conclusions: </bold>Self-help interventions with increased intensity and duration resulted in significantly improved abstinence rates that extended 6 months beyond the end of the intervention. Despite the greater intensity, the interventions were highly cost effective, suggesting that widespread dissemination in healthcare settings could greatly enhance quitting.<bold>Trial Registration: </bold>This study is registered at www.clinicaltrials.gov NCT01352195. [ABSTRACT FROM AUTHOR]