Eligible studies were published primary studies without restriction of study design. Studies were required to measure self efficacy pre and post intervention. The intervention had to target self efficacy in the context of behaviour change. Self efficacy and behaviour change were not defined. Specific inclusion criteria for participants were not reported.
Studies were conducted in the USA, Canada, the Netherlands and Taiwan. The setting included schools, hospitals, community settings and treatment centres. Participants were either from the general population or from specific groups such as inpatients from a treatment program, high school students or cardiac patients. Addiction behaviours targeted were tobacco smoking, alcohol, anabolic steroids, substance abuse and drug dependency. All of the studies measured self efficacy. More than half the studies also measured behaviour change. The interventions used verbal persuasion and activities to increase self efficacy. Interventions ranged from group activities to computer-generated letters providing persuasive information on self help.
One reviewer screened abstracts for inclusion. A second reviewer assessed a subset of 30 abstracts. The authors stated neither how full text studies were selected for inclusion nor how disagreements were resolved relating to final selection.