Pederson 1979.

Methods	Country: Canada. Study sites: not stated Study period: not stated. Recruitment: community volunteers. Sample size calculation: not mentioned.
Participants	Number of participants: 65 smokers (17 in live‐hypnosis group and 16 each for other groups). Inclusion criteria: not stated. Exclusion criteria: not stated. Overall demographics: mean age: 41.7; mean years smoked: 23.2; mean base line smoking: 28.2 CPD. All participants had quit smoking at least once prior to participation; range of abstinence varied from < day to > 1 year.
Interventions	a) Live hypnosis and counselling. b) Videotape hypnosis and counselling. c) Relaxation hypnosis (no mention of smoking) and counselling. d) Counselling alone. All groups received 6 x weekly sessions followed by 3 x monthly sessions of group counselling with presentation and discussion of various techniques which could be employed for quitting. The hypnosis session for groups a), b) and c) occurred at the third weekly session. Duration of intervention: approximately 4.5 months. Duration of follow‐up: 6 months.
Outcomes	Definition of smoking cessation: no smoking for at least 3 months at 6 months post‐treatment. Adverse events: no information provided on whether or not AE data were collected and whether any AEs occurred.
Notes	Funding: Ontario Thoracic Society. Author declaration of interest: not reported. Additional notes: this study, Pederson 1975 & Pederson 1980 were undertaken by same authors and funded by the same party.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Randomized, method not stated
Allocation concealment (selection bias)	Unclear risk	No details given
Blinding of outcome assessment (detection bias) All outcomes	High risk	Blinding would not have been possible for hypnotherapy versus control comparison. Outcomes self‐reported.
Incomplete outcome data (attrition bias) All outcomes	High risk	The author stated that "after the hypnosis session (3rd weekly session), the attendance for the live‐hypnosis plus counselling group remained at 75% to 100%, while the attendance of the remaining three groups dropped to about 50%". All participants were included in the analysis; no specific information regarding subjects lost to follow up.
Selective reporting (reporting bias)	Low risk	All outcomes reported as described in the methods section