Pickworth 1997.

Methods	Randomized trial of electrostimulation Country: USA Recruitment: 'from community'
Participants	121 adults aged over 21 yrs, smoking >20/day for at least 1 yrs, no psychoactive medications; without pregnancy, drug history, medical condition, implanted device, history of seizures or migraine
Interventions	5 consecutive days of 60 min of a) electrostimulation, 10Hz 2 msec pulse, 30 µamp to mastoid, or b) sham electrostimulation
Outcomes	Abstinence after 5 days and 1 month, verified by exhaled CO. Withdrawal symptoms.
Notes	Stimulation parameters were criticised by Boutros 1998
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	"the instrument manufacturer 'prepared sealed envelopes containing a cartridge and an insert that was randomly assigned to each subject' but method of sequence generation not described
Allocation concealment (selection bias)	Low risk	Sealed envelopes prepared with cartridge and insert
Blinding (performance bias and detection bias) All outcomes	Low risk	Described as double‐blind, and interventions were appropriate
Incomplete outcome data (attrition bias) All outcomes	Low risk	Dropout rates 16% and 17%
Other bias	Low risk	No baseline differences