Does socioeconomic position moderate the associations between the content and delivery features of digital behaviour change interventions for smoking cessation and intervention effectiveness? A systematic review and meta-analysis

Prior research indicates that digital smoking cessation interventions can be effective, but little is known about their active ingredients. Therefore, this review aimed to examine the associations of content (behaviour change techniques [BCTs]), delivery features (delivery mode, readability, ease-of-use), and socioeconomic position with effectiveness. Systematic searches and hand searches were conducted from February to June 2023 to identify experimental evaluations of digital smoking cessation interventions published since 2004. Random-effects meta-analyses were used to explore intervention effectiveness. Meta-CART were used to explore whether content, delivery features, or socioeconomic position moderate effectiveness and assessed interactions between potential moderators. Meta-regressions were performed as sensitivity checks. For k = 29 studies (n = 42,662), the authors provided sufficient data and materials for inclusion in the primary analyses. Participants in the intervention groups had greater odds of successfully quitting smoking (OR = 1.29, 95% CI: 1.10–1.51, p =.002) with similar effect sizes across socioeconomic groups (OR_{low SEP}= 1.25, 95% CI: 1.00–1.57, p =.048; OR_{high SEP}= 1.36, 95% CI: 1.06–1.76, p =.017). No delivery features were significantly associated with effectiveness. The BCT ‘commitment’ was associated with larger effects in populations with high, but not low, socioeconomic positions. There were no significant interactions between potential moderators. Digital smoking cessation interventions are effective across socioeconomic groups. Uncertainty around active ingredients remains.