Long-Term Effectiveness of a Digital Therapeutic Intervention for Smoking Cessation: A Randomized Controlled Trial

Abstract

Background: Smoking is the leading cause of preventable mortality worldwide. Digital therapeutic interventions offer a novel approach to smoking cessation and overcome many barriers to accessibility of traditional methods. Yet, the long-term efficacy of these interventions is largely unknown. Based on a chronic disease model of smoking, the present study evaluated the effects of Quit Genius, a novel, long-term digital therapeutic intervention for smoking cessation. Methods and Findings: Using a single-blind, two-arm parallel-group, randomized controlled trial design, adult smokers of 5 or more cigarettes per day (N=556) were recruited between January and November of 2019 via social media advertisements and referrals from primary care practices in the UK. Participants were offered nicotine replacement therapy for a 12-week period and randomly assigned to one of two interventions.The Quit Genius group received a digital therapeutic intervention for smoking cessation comprising a clinician supported smartphone application delivering cognitive behavioral therapy (CBT). The CBT component included self-directed coping skills training and individually tailored therapeutic content, coupled with personalized clinician-delivered counselling via instant messaging. The control intervention was Very Brief Advice, a face-to-face, single session intervention based upon the Ask, Advise, Act model. Half of each group received a carbon monoxide (CO) device for biochemical verification of smoking abstinence. The primary outcome, by intention to treat (ITT), was sustained abstinence at 4, 26, and 52 weeks post-quit date. Secondary outcomes included self-reported 7-day point prevalence abstinence at 26 and 52 weeks post-quit date, and self-reported quit attempts and putative mechanisms of action of CBT for smoking cessation, including self-efficacy and psychological well-being. Participants (N=556) were randomly assigned to Quit Genius (n=277) or the Very Brief Advice control condition (n=279). The final sample included 530 participants, comprising roughly equivalent proportions of men (n=291; 54%) and women, averaging 41 years of age (SD=12), who smoked an average of 15 cigarettes per day (SD=7). Using an Intention-to-treat (ITT) analysis, seven-day point prevalence abstinence from weeks 4 through 52 ranged from approximately 27% to nearly 45% among those who received the Quit Genius intervention, and from 13% to 29% for those in the control condition. Continuous smoking abstinence at 26 and 52 weeks occurred in 27.2% and 22.6% of Quit Genius participants, respectively, relative to 16.6% and 13.2% of those assigned to the control group; Quit Genius participants were more likely to remain abstinent than those in the control group Relative Risk [RR]= 1.71, 95% CI 1.17-2.50; p=0.005). Conclusions: Using an extended care model combining NRT with evidence-based psychosocial treatment, a digital therapeutic intervention (Quit Genius) produces continuous abstinence rates that are notably higher than those typically observed in the literature. Trial Registration: The trial was registered in the ISRCTN database on December 18, 2018 (https://www.isrctn.com/ISRCTN65853476).