Variability and effectiveness of control group interventions in smoking cessation trials: A systematic review and meta-analysis

Nicola Black, Maarten C. Eisma, Wolfgang Viechtbauer, Marie Johnston, Robert West, Jamie Hartmann-Boyce, Susan Michie, Marijn de Bruin

Research output: Contribution to journalAbstractpeer-review


Background/purpose: We aimed to examine variability and effectiveness of interventions provided to comparator groups in smoking cessation trials.
Methods: We conducted a systematic review of randomised controlled
trials (RCTs) of behavioural interventions for smoking cessation amongst adults, with or without stop-smoking medication (registration: CRD42015025251 and We searched the Cochrane Tobacco Addiction Group Specialized Register for RCTs, published between 1/1996-11/2015, with objective outcomes measured at ≥6 months. Study authors were contacted to obtain comprehensive descriptions of their comparators. Meta-regression analyses examined the relationships of smoking cessation rates with stop-smoking medication and behaviour change techniques (BCTs).
Results: 104 of 142 eligible comparator groups (N=23706) had complete data and were included in analyses. There was considerable variability in the number of BCTs delivered (M=15.97, SD=13.54, range:0-45) and the provision of smoking cessation medication (43% of groups received medication) across comparator groups and within categories of comparator groups (e.g., usual care, brief advice). Higher smoking cessation rates were predicted by provision of medication (B=0.334, 95%CI: 0.030- 0.638, p=.031) and number of BCTs included (B=0.020, 95%CI: 0.008- 0.032, p<.001). Modelled cessation rates in comparator groups that received the most intensive support were 15 percentage points higher than those that received the least (23 versus 8%).
Conclusions and implications: Interventions delivered to comparator groups in smoking cessation trials vary considerably in content, and cessation rates are strongly predicted by stop-smoking medication and number of behaviour change techniques delivered. This should be considered when synthesising and interpreting the results of such trials.
Original languageEnglish
Pages (from-to)S48-S49
Number of pages2
JournalInternational Journal of Behavioral Medicine
Issue numberSUPPL 1
Early online date5 Jun 2021
Publication statusPublished - Jun 2021


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