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

Abstract

Aims: To examine variability and effectiveness of interventions provided to comparator (control) groups in smoking cessation trials.

Methods: Systematic review with meta-analysis of randomized controlled trials (RCTs) of behavioral interventions for smoking cessation, with or without stop-smoking medication. We searched the Cochrane Tobacco Addiction Group Specialized Register for RCTs with objective outcomes measured at ≥ 6 months. Study authors were contacted to obtain comprehensive descriptions of their comparator interventions. Meta-regression analyses examined the relationships of smoking cessation rates with stop-smoking medication and behavior change techniques.

Results: One hundred and four of 142 eligible comparator groups (n = 23 706) had complete data and were included in analyses. There was considerable variability in the number of behavior change techniques delivered [mean = 15.97, standard deviation (SD) = 13.54, range = 0-45] and the provision of smoking cessation medication (43% of groups received medication) throughout 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% confidence interval (CI) = 0.030-0.638, P = 0.031] and number of behavior change techniques included (B = 0.020, 95% CI = 0.008-0.032, P < 0.001). 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: Interventions delivered to comparator groups in smoking cessation randomized controlled trials vary considerably in content, and cessation rates are strongly predicted by stop-smoking medication and number of behavior change techniques delivered.

Keywords: Behavior change techniques; comparator group; control group; meta-analysis; meta-regression; smoking cessation; systematic review.

Figure 1

Preferred Reporting Items for Systematic Reviews and Meta‐Analyses (PRISMA) flow diagram. BCTs = behavior change techniques

Figure 2

Predicted smoking cessation rates across the observed range of (a) total behavior change techniques (BCTs) and (b) personalized, person‐delivered BCTs. Dotted lines represent 95% confidence intervals. Estimated smoking cessation rates are computed at 6‐month follow‐up, non‐cotinine verified, point prevalence abstinence and mean levels of age and nicotine dependence. [Colour figure can be viewed at wileyonlinelibrary.com]