Thirty-seven RCTs of variable quality met the inclusion criteria. The included trials focused on seven target behaviours: smoking cessation, physical activity, dietary change, multiple lifestyle changes, screening mammography, treatment adherence in the context of mental illness, and preventing the uptake of unhealthy behaviours such as smoking and alcohol use.
There was little evidence to support the effectiveness of stage-based interventions as a basis for behaviour change or for facilitating stage progression, irrespective of the comparator (other types of intervention, no intervention, or usual care). The authors appropriately highlighted the need for stronger evaluations of theory-based interventions.