Underreporting of the active content of behavioural interventions: a systematic review and meta-analysis of randomised trials of smoking cessation interventions

Marijn de Bruin*, Nicola Black, Neza Javornik, Wolfgang Viechtbauer, Maarten C. Eisma, Jamie Hartman-Boyce, A. Jess Williams, Robert West, Susan Michie, Marie Johnston

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

28 Citations (Scopus)
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Despite its importance, underreporting of the active content of experimental and comparator interventions in published literature has not been previously examined for behavioural trials. We assessed completeness and variability in reporting in 142 randomised controlled trials of behavioural interventions for smoking cessation published between 1/1996 and 11/2015. Two coders reliably identified the potential active components of experimental and comparator interventions (activities targeting behaviours key to smoking cessation and qualifying as behaviour change techniques, BCTs) in published, and in unpublished materials obtained from study authors directly. Unpublished materials were obtained for 129/204 (63%) experimental and 93/142 (65%) comparator groups. For those, only 35% (1200/3403) of experimental and 26% (491/1891) of comparator BCTs could be identified in published materials. Reporting quality (#published BCTs/#total BCTs) varied considerably between trials and between groups within trials. Experimental (vs. comparator) interventions were better reported (B(SE) = 0.34 (0.11), p <.001). Unpublished materials were more often obtained for recent studies (B(SE) = 0.093 (0.03), p =.003) published in behavioural (vs. medical) journals (B(SE) = 1.03 (0.41), p =.012). This high variability in underreporting of active content compromises reader's ability to interpret the effects of individual trials, compare and explain intervention effects in evidence syntheses, and estimate the additional benefit of an experimental intervention in other settings.

Original languageEnglish
Pages (from-to)195-213
Number of pages20
JournalHealth Psychology Review
Issue number2
Early online date13 Jan 2020
Publication statusPublished - 2021

Bibliographical note


We thank the authors of the included studies who responded to our requests for materials on the (intervention and) comparator group support. These materials were crucial to achieving our current aims. We also thank the members of our advisory board panels, who provided valuable input into the broader study design.


This work was funded by Cancer Research UK (grant number C50862/A18446). The systematic review protocol was previously peer-reviewed by Cancer Research UK as part of the funding process. The funders had no role in protocol design, decision to publish, or preparation of the manuscript.


  • behaviour change technique
  • control group
  • intervention group
  • randomised controlled trial
  • reporting
  • Systematic review
  • CARE


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