Barkley 1977.
| Methods | Site: USA, Bowling Green State University, Ohio. Study period: not stated. Recruitment: advertisements distributed in the university community. Sample size calculation: not mentioned. | |
| Participants | Number of participants: 36 smokers (12 in each group). Inclusion criteria: not stated. Exclusion criteria: those not able to meet demands of procedures including scheduling of treatment sessions, random assignment to groups, data collection, deposit requirements, etc. Overall demographics: primarily students and university affiliated persons, all of whom were young adults; 42% female. | |
| Interventions | a) Rapid smoking (based on a modified version of that reported by Keutzer 1968). b) Group hypnosis (hypnotic suggestions were the same as those reported by Hall and Crasilneck 1970). c) Attention placebo (watching films, receiving and discussing handouts on the topic, discussion of problems they might be experiencing in quitting smoking). All treatments: 7 x 1‐hour sessions over 2 weeks; first and last 15 mins spent discussing problems with quitting smoking, while 30 mins in the middle spent in treatment procedures. | |
| Outcomes | Definition of smoking cessation: point‐prevalence abstinence at 9‐month follow up. Adverse events: no information provided on how AE data were collected; number of participants in rapid smoking group experiencing vomiting was reported. | |
| Notes | Funding: partly supported by Department of Psychology, Bowling Green State University, fund. Author declaration of interest: not reported. |
|
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Randomized, method not stated, possibly stratified by gender |
| Allocation concealment (selection bias) | Unclear risk | No details given |
| Blinding of outcome assessment (detection bias) All outcomes | High risk | Blinding not possible due to nature of intervention; self‐report only |
| Incomplete outcome data (attrition bias) All outcomes | Low risk | 7 participants missed at least one treatment session: (a) 0; (b) 4; (c) 3; not included in the original analysis, but included in our recalculations, following ITT analyses with missing assumed smoking. |
| Selective reporting (reporting bias) | Low risk | All outcomes reported as described in the methods section |