Effectiveness of Peer-Support Interventions for Smoking Cessation: A Systematic Review and Meta-analysis

Abstract

Introduction: Peer support has been recommended to promote smoking cessation, but results from prior meta-analyses have not established its efficacy. We conducted a systematic review and meta-analysis to assess current evidence and identify potential modifiers of efficacy.

Methods: Randomized controlled trials of peer-support interventions with a smoking cessation outcome were identified in January 2022 from PubMed and references listed in identified studies. The meta-analysis outcome measure was mean risk ratio (RR, 95% confidence interval [CI]) for abstinence at the longest follow-up timepoint between 3 and 9 months from baseline. Potential modifiers tested were peer smoking status (former, current, or unknown), follow-up timepoint, abstinence measure, and cumulative engagement time between peers and smokers ("dose"). Studies were assessed for risk of bias and certainty of evidence.

Results: We identified 16 trials, which varied in abstinence effect size (RR 0.61-3.07), sample size (23-2121), dose (41-207 minutes), and follow-up timepoint (<1-15 months). Across 15 trials with follow-up between 3 and 9 months (N = 8573 participants; 4565 intervention, 4008 control), the pooled Mantel-Haenszel RR was 1.34 (95% CI: 1.11-1.62). Effect sizes were greatest among interventions with formerly smoking peers (RR 1.43, 95% CI 1.17-1.74; five trials). We found positive effects for follow-up timepoints ≥3 months but no effect of intervention dose. The overall quality of evidence was deemed "very low."

Conclusions: Peer-support interventions increased smoking abstinence. There remains a lack of consensus about how to define a peer. Intervention features such as peer smoking status appear to have explanatory power. Additional high-quality and more comparable trials are needed.

Implications: This study reviewed the latest evidence from randomized controlled trials and found that peer-support interventions enhance smoking cessation. Efficacy varies with key intervention features such as peer smoking status and follow-up timepoint, which may be used to facilitate development of more effective peer-support interventions. Future trials and reviews would benefit from careful consideration and clear reporting of peer smoking status, length of follow-up, abstinence measures, and intervention dose.