Calle 1994.

Methods	Setting: Florida, USA Recruitment: Volunteers from two local American Cancer Society (ACS) units. Recruitment was primarily through a word‐of‐mouth campaign encouraging current volunteers to participate and recruit others among their acquaintances and organisations. Each volunteer was asked to list the names, addresses and phone numbers of 10 women whom she knew and would be willing to contact by telephone over a six‐month period and encourage to have a mammogram. Randomisation: RCT 2 arm. There was no clear definition of peer support, however study met the inclusion criteria of using peers that shared one or several key characteristics of the target population. Peer training: There was a half day training session including presentations on mammography and details of facilities, American Cancer Society Breast Health Guidelines, instructions for intervention, practice sessions, a breast cancer fact sheet and a resource guide for local mammography centres.
Participants	594 women aged over 40 years.
Interventions	Intervention: During a six month intervention period volunteers called their five intervention participants up to three times. At initial contact they emphasized the importance of receiving regular mammograms and asked the participant to set a date by which she would schedule an appointment for screening. During subsequent calls, volunteers determined if the appointment had been made and kept. If at the initial contact, the participant said she had had a mammogram within the last year, she was not called again but congratulated and encouraged to continue receiving regular mammograms. Control group: No intervention. Caller: Calls made by peer supporters.
Outcomes	Physical health outcomes: none reported. Psychological health outcomes: none reported. Behavioural health outcomes: Mammography usage (questionnaire developed for use in study ‐ self report (not validated)). Social health outcomes: none reported. Impact on participants: none reported. Impact on peer supporter: none reported. Method of assessing outcome measures: phone survey.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	Unclear risk	Unclear.
Allocation concealment?	Unclear risk	B ‐ Unclear.
Blinding? Participants	Unclear risk	Unclear.
Blinding? Providers	Unclear risk	Unclear.
Blinding? Outcome assessors	Low risk	Quote "The interviews were administered during a two week period by an outside contractor unknown to the participants."
Blinding? Data analysts	Unclear risk	Unclear.
Incomplete outcome data addressed? All outcomes	High risk	The response rate for the post‐intervention interview was 76% for women in the intervention group and 79% in the control group. Total lost to follow‐up 23% (175).
Free of selective reporting?	Low risk	Mammography usage was the only outcome measured.