Effectiveness of smoking cessation interventions among adults: an overview of systematic reviews.

backgroundThis overview of reviews aims to identify evidence on the benefits (i.e. tobacco use abstinence and reduction in smoking frequency) and harms (i.e. possible adverse events/outcomes) of smoking cessation interventions among adults aged 18 years and older.

methodsWe searched Medline, Embase, PsycINFO, Cochrane Database of Systematic Reviews, Database of Abstracts of Reviews of Effects, the CADTH Health Technology Assessment Database and several other websites for grey literature. Searches were conducted on November 12, 2018, updated on September 24, 2020, with publication years 2008 to 2020. Two reviewers independently performed title-abstract and full-text screening considering pre-determined inclusion criteria. Data extraction and quality assessments were initially completed by two reviewers independently (i.e. 73% of included studies (n = 22)) using A Measurement Tool to Assess Systematic Reviews-2 (AMSTAR 2), and the remainder done by one reviewer and verified by another due to resources and feasibility. The application of Grading of Recommendations Assessment, Development and Evaluation (GRADE) was performed by one independent reviewer and verified by another.

resultsA total of 22 Cochrane systematic reviews evaluating the impact of smoking cessation interventions on outcomes such as tobacco use abstinence, reduction in smoking frequency, quality of life and possible adverse events were included. Pharmaceutical (i.e. varenicline, cytisine, nicotine replacement therapy (NRT), bupropion) and behavioural interventions (i.e. physician advice, non-tailored print-based self-help materials, stage-based individual counselling, etc.) showed to have increased smoking cessation; whereas, data for mobile phone-based interventions including text messaging, hypnotherapy, acupuncture, continuous auricular stimulation, laser therapy, electrostimulation, acupressure, St John's wort, S-adenosyl-L-methionine (SAMe), interactive voice response systems and other combination treatments were unclear. Considering harms related to smoking cessation interventions, small/mild harms (i.e. increased palpitations, chest pain, nausea, insomnia, headache) were observed following NRT, varenicline and cytisine use. There were no data on harms related to behavioural therapies (i.e. individual or group counselling self-help materials, internet interventions), combination therapies or other therapies (i.e. laser therapy, electrostimulation, acupressure, St John's wort, SAMe).

conclusionResults suggest that pharmacological and behavioural interventions may help the general smoking population quit smoking with observed small/mild harms following NRT or varenicline. Consequently, evidence regarding ideal intervention strategies and the long-term impact of these interventions for preventing smoking was unclear. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42018099691.