Table S1: Qualitative and mixed methods studies included in analysis for review question on positive and negative impacts

1 Study C Methods He Nature of intervention/ Population/ setting Vali ou alt scheme dity nt h Scor ry to e1 pic s Ashton C. Healing from the inside: Ca One semi-structured interview, one Re Circle of Knowledge “Healing Lodge” – a small 3b an analysis of correctional service of na interview by email and publicly du Keepers (CKK) Peer (28 bed) minimum/ medium Canada's circle of Knowledge da available documents including cti education and Counseling security prison for Keepers Program. Canada: strategic plans, evaluation reports on (PEC) program: a peer Aboriginal women, University of Toronto; 2010. and operational outlines of educational and support incorporating Aboriginal spr programme, based within healing practices, ea a ‘healing lodge’ meaningfulness and d cultural-connection. No of fences, lock or bars. inf Women live in communal ect cottages, cook meals iou together. Most women are s serving sentences of 3 years dis or less. eas e, sp eci fic all y HI V/ AI DS an d H C V Betts-Symonds G. Community Ire Lessons learned workshop He Peer education 700 prisoners in Wheatfield 3c based health & first aid in action in la involving all prisons collectively. alt prison, Dublin Ireland Irish prisons. 3 year evaluation. nd Self reports from prisoner h, (medium-high security male Dublin: Irish Prison Service; 2012. volunteers and staff. hy prison) and their immediate

1 Validity score: 1 = good internal validity, 2 = moderate internal validity and 3 = poor internal validity; a = highly relevant, b = of some relevance and c = not very relevant.

2 Study C Methods He Nature of intervention/ Population/ setting Vali ou alt scheme dity nt h Scor ry to e pic s Interviews with prison governors & gie family members staff ne an d cle anl ine ss

Blanchette, K. Eljdupovic-Guzina Ca Semi-structured interviews with Ge Peer support Women resident in one of 2b G. Results of a Pilot Study of the na offenders and staff. ner four small prisons in Peer Support Program for Women da Focus groups with offenders. al Canada: Nova Institution; Offenders. Canada: Correctional Questionnaire surveys of offenders em Establishment Joliette; Service of Canada; 1998. and staff. oti Grand Valley Institution; on Edmonton Institution. al/ me nta l he alt h, ps yc hol ogi cal su pp ort an d co un sel lin g

3 Study C Methods He Nature of intervention/ Population/ setting Vali ou alt scheme dity nt h Scor ry to e pic s Boothby MRK. Insiders’ views of U Two focus groups; 3 Insiders Ge Peer support Male prison in the UK. The 1a their role: toward their training. Can K participated. ner scheme supports prisoners J Criminol 2011;53:424–48. al who are new to the prison he system. alt h/ su pp ort

Boyce I, Hunter G, Hough M. Peer U 73 semi-structured interviews with Ho Peer advisors Serving prisoners in: 3 2a advice project. An evaluation. K 34 Peer Advisors based in prison usi category B prisons (male), 1 London: St Giles Trust, King's and in the community. ng/ Youth Offending Institution College; 2009. 64 semi-structured interviews with res (male) St Giles Trust staff, Prison Officers, ettl resettlement, governors, probation em and CARAT and other advice ent workers based in prison. 25 interviews with clients of the prison Peer Advice service. 4 focus groups with volunteers and clients of the community resettlement service, involving a total of 23 participants. A focus group with clients of the prison Peer Advice service. Observations of NVQ training and the delivery of Peer Advice work in prison. Observations of mentoring work in the community. Review of operational documents. Review of project monitoring. Collation of activity monitoring for prison and community projects.

4 Study C Methods He Nature of intervention/ Population/ setting Vali ou alt scheme dity nt h Scor ry to e pic s Brooker C, Sirdifield, C. New U Telephone interviews with 3 Health M Health Trainers Serving prisoners in 4 adult 1a futures Health trainers: An impact K Trainer tutors and key staff; post- ult prison, one Young assessment. Lincoln: University of training survey (n=17). ipl Offenders Institution and Lincoln; 2007 Focus groups with Health Trainer e one probation setting tutors (n=11) and Health Trainers he and attending a sample of steering alt group meetings (n=4) and obtaining h minutes of these meetings. iss Data captured through a ‘clinical ue activity data form’ and recorded s information on the first fifteen clients that each Health Trainer saw.

Cichowlas JA, Chen Y-J. Volunteer U Volunteer inmates were interviewed So Peer support Ill or dying prisoners in 3c prisoners provide hospice to dying S cia Dixon Hospice in Illinois. inmates. Ann Health Law A l 2010;19:127–32. su pp ort Collica K. The prevalence of HIV U Quantitative and qualitative data HI Peer education All prisons and prisoners in 3c peer programming in American S collected via survey from 51 state V USA prisons: an opportunity wasted. J A departments of corrections and ed Correct Health Care 2007;13:278– Federal Bureau of Corrections from uc 88. January – September 2005. In total, ati 1,280 facilities and 1,427,279 on inmates were covered by this survey. Collica K. Surviving incarceration: U One-to-one interviews with 49 HI Peer education Aimed at women in prison 1b two prison-based peer programs S female offenders (inmate peers) V/ with HIV/AIDS. build communities of support for A who work in a HIV prison-based AI One maximum and one female offenders. Deviant Behav peer program. DS medium security prison for 2010;31:314–47. an women d H C V

5 Study C Methods He Nature of intervention/ Population/ setting Vali ou alt scheme dity nt h Scor ry to e pic s (& oth er inf ect iou s dis eas es)

Correctional Service of Canada. Ca Interviews with 12 peer counsellors Fo Peer Support Team (peer Women’s Prison in Kinston, 3b Opening the window on a very dark na (qualitative). cu counselling) Ontario (Canada). Women day: A program evaluation of the da Survey of inmate population s prisoners “in distress”. Peer Support Team in the Kingston (quantitative). on Prison for women. Ottawa, wo Correctional Service of Canada; me 2009 n pri so ner s wit h a his tor y of chi ldh oo d se xu al ab us

6 Study C Methods He Nature of intervention/ Population/ setting Vali ou alt scheme dity nt h Scor ry to e pic s e. Davies B. The Swansea Listener U In-depth interviews with 6 Listeners Su Listeners HMP Swansea (adult 2b Scheme: views from the prison K and 20 members of staff (selected ici prison) landings. Howard J Crim Justice randomly). 4 prisoners were based de/ 1994;33:125–35. on the adult remand and convicted Sel wings, two prisoners were located f on the segregation unit. har m

Delveaux K. Blanchette K. Results Ca Questionnaires, surveys of Ge Peer support Small women’s prison. 3c of an Evaluation of the Peer Support na offenders and staff. ner Women prisoners, all Program at Nova Institution for da Semi-structured interviews with al serving sentences of two or Women. Canada, Research Branch, offenders and staff; focus groups em more years and classified as Correctional Service of Canada; with offenders. 18 offenders were oti minimum or medium 2000. interviewed; 1 peer support team on security. (PST) member, 4 PST trainees and al/ 13 other offenders. 22 staff me members were interviewed. nta l he alt h, ps yc hol ogi cal su pp ort an d co un sel lin g

7 Study C Methods He Nature of intervention/ Population/ setting Vali ou alt scheme dity nt h Scor ry to e pic s

Dhaliwal R, Harrower J. Reducing U Cross-sectional qualitative study. Su Listeners Vulnerable or distressed 2b prisoner vulnerability and providing K Qualitative interviews (intervention ici prisoners, or those at risk of a means of empowerment: group only) using interpretative de/ suicide. evaluating the impact of a listener phenomenological analysis. 50-60 Sel scheme on the listeners. Br J minute semi-structured interviews. f Forensic Pract 2009;11:35–43. Nine individuals met the inclusion har criteria of having been a Listener m for a minimum of six months, and 7 individuals agreed to take part Eamon KC, McLaren DL, Munchua Ca Quantitative (survey) and Ge Peer Support Edmonton Institution for 3b MM, Tsutsumi LM. The peer na qualitative (interviews). Update to ner Women. support program at Edmonton da Blanchette 1998, carried out in al Institution for Women. Forum April 1999. 26 prisoners and 13 em 2012;11:28–30. staff members responded to survey. oti on al/ me nta l he alt h, ps yc hol ogi cal su pp ort an d co un sel lin

8 Study C Methods He Nature of intervention/ Population/ setting Vali ou alt scheme dity nt h Scor ry to e pic s g

Edgar K, Jacobson J, Biggar U Survey of prisons and interviews M Peer support/ Listeners 12 prisons. No information 2b K.Time Well Spent: A practical K with prisoners and staff involved in ult given on target recipients. guide to active citizenship and active citizenship schemes in 12 ipl volunteering in prison. Prison prisons. (The report mainly draws e Reform Trust London, Prison on the qualitative data) he Reform Trust; 2011 alt h iss ue s

Foster J. Peer support in prison U Face-to-face interviews with 6 Su Listeners Adult category-B local male 1a health care. An investigation into K Listeners; 7 prisoners who had used ici prison. Operational the Listening scheme in one adult the Listening scheme; 7 prisoners de/ capacity 1103 male prison. London, School of who had not used the Listening Sel Health & Social Care, University of scheme; 2 prison officers; 6 health f Greenwich; 2011 care professionals and the har Samaritan Branch Prison Support m Officer. Two Listener training sessions and one Safer Custody Group meeting were also observed. Hall B, Gabor P. Peer suicide Ca Data collected via examining Su Listeners Medium security prison 3c prevention in a prison. Crisis na records and documents including ici with capacity 585. Inmates 2004;25:19–26. da program manuals, minutes of de have committed serious meetings, training records and pre crimes. statistics from the Samaritans of ve Modal age category 18-29 Southern Alberta. nti years, followed by 30-39 Interview and survey information on years. Length of sentence also collected from key ranged from 2 years to life. stakeholders including the SAMS in the Pen volunteers, correctional

9 Study C Methods He Nature of intervention/ Population/ setting Vali ou alt scheme dity nt h Scor ry to e pic s staff, general inmates, and professional staff. 17 interviews conducted with SAMS volunteers; 14 interviews conducted with professionals (parole officers); 12 interviews conducted with nurses, mental health staff, psychologists, chaplains, unit managers Surveys completed by 126 inmates & 27 correctional officers. Hoover J, Jurgens R. Harm M Research involved 7 site visits to HI Peer outreach 7 prisons (6male prisons 3c reduction in prison: The Moldova ol prisons and 1 to a pretrial detention V/ and 1 female prisons) Model. New York, Open Society do facility as well as visits to the AI Institute; 2009 va headquarters of the penitentiary DS system and NGO that provides an harm reduction services in prisons. d Interviews (numbers not known) H were conducted with prisoners, C pretrial detainees, NGO staff, V penitentiary system officials & (& employees at both national & local oth levels. er inf ect iou s dis eas es) Hunter G, Boyce I. Preparing for U 44 semi-structured interviews with Ho Peer advisors Prisoners requiring housing 1a Employment: Prisoners' Experience K 28 offenders in prison and post- usi advice in 5 prisons in South of Participating in a Prison Training release. Interviewees were ng/ East England (Three Programme. The Howard Journal of recruited from five prisons (n=22) res Category B prisons (male), Criminal Justice. 2009; 48:117-31 and from the community project ettl one young offender (n=56). em institution (male) and one ent female open prison.)

10 Study C Methods He Nature of intervention/ Population/ setting Vali ou alt scheme dity nt h Scor ry to e pic s

Jacobson, J, Edgar K. There when U A study in England with 91 Ge Peer support Prisoners on their first night 2c you need them most: Pact's first K prisoners interviewed across 6 ner The Prison Advice and in prison. night in custody services. London, prisons- HMP Holloway, al care Trust (PACT) first No differentiation between Prison Reform Trust; 2009. Wandsworth and Exeter and 3 he night services, includes experienced prisoners (who comparator prisons (One-to-one alt the use of insiders. PACT had previously been in interviews with 15 prisoners from h/ services include prison) and those who had each prison). su providing information never been in prison before. pp about the prison; practical Holloway prison, Exeter A study from a prison in Scotland ort help such as making a prison, Wandsworth prison- (One-to-one interviews with 15 phone call; emotional intervention runs either in prisoners from HMP Edinburgh)/ support; liaising with the Prison visitors centre or families in dedicated first night suites. Levenson J, Farrant F. Unlocking U Fieldwork was undertaken in eight M Peer support schemes, National survey of all 2b potential: active citizenship and K prisons selected to represent all ent including Listeners. prisons in England and volunteering by prisoners. Probat J types of prisons, and which had also al Wales. 2002;49:195–204. been identified from the survey as he having examples of good practice. alt In total, 82 prisoners and 18 h, members of staff were spoken to. su bst an ce mi sus e, ge ner al he alt h, ho usi ng su

11 Study C Methods He Nature of intervention/ Population/ setting Vali ou alt scheme dity nt h Scor ry to e pic s pp ort . Maull FW. Hospice care for U Six month pilot program evaluation Ge Prison hospice volunteers Ill prisoners at U.S. Medical 2b prisoners: establishing an inmate- S included: a review of all the visit ner Centre for Federal Prisoners staffed hospice program in a prison A reports submitted after each patient al in Springfield, Missouri medical facility. Hospice J visit; all hospice team meeting he 1991;7:43–55 minutes; all program alt correspondence; and the results of h/ three separate anonymous su questionnaires, one each for pp hospital staff (physicians, nurses, ort and correctional officers), patients, and inmate hospice volunteers. Munoz-Plaza CE, Strauss SM, U Inmates participated in individual HI Peer education A state correctional facility 2b Astone JM, Des Jarlais DC, Hagan S face to face semi-structured V/ in California. Drug H. Hepatitis C service delivery in A interviews as well as a focus group. AI treatment program is prisons: peer education from the Drug treatment program staff DS located on a medium ‘guys in blue’. J Correct Health members also participated in an security prison yard that Care 2005;11:347–68. individual face to face interviews. d houses male inmates. Age Five inmates participated in the H range 20 – 50 years. individual interviews and 6 in the C focus group. V (& oth er inf ect iou s dis eas es)

Penn State Erie. Final Report of the U This study had 4 components: Pa Peer-led fathering Pennsylvania Department of 3c Process Evaluation of the Long S survey of inmates; caregiver ren program. The LDD Corrections at the State Distance Dads Program. Erie. PA: A telephone interviews; face-to-face tin program is designed to Correctional Institution at

12 Study C Methods He Nature of intervention/ Population/ setting Vali ou alt scheme dity nt h Scor ry to e pic s Penn State Erie; 2001. inmate interviews; and institutional g assist incarcerated men in Albion (Erie county). data collection. Quantitative and developing skills to Fathers in prison. qualitative data collected via survey become more involved from participants in 3, 12-week and supportive fathers. LDD sessions. Telephone interviews were conducted with the caregivers of the LDD participants’ children. Face- to-face interviews were also conducted with a randomly selected sample of LDD participants from session 1, and also regularly collected DOC data. Schinkel M, Whyte B. Routes out of U A total of 123 client/prisoner Ho Peer mentoring Based in Glasgow – prisons 2b prison using life coaches to assist K interviews were conducted; 49 usi not stated. Prisoners serving resettlement. Howard J Crim Justice prisoners pre-release, 54 post- ng/ sentences of between three 2012;4:359–71. release, and 20 at both stages. All of res months and four years. the Life Coaches (14) employed by ettl Service offered to eligible the project were interviewed twice em prisoners who are returning and consulted through focus groups, ent to Glasgow, Renfrewshire twice at different points in the life and North Lanarkshire. of the project. Scott DP, Harzke AJ, Mizwa MB, U Qualitative data collected via initial HI Peer education Prisoners at 5 Texas prison 2c Pugh M, Ross MW. Evaluation of S (March 1999) and follow-up (June/ V facilities. A diversity of an HIV peer education program in A July 1999) interviews with wardens pre facilities was selected Texas prisons. J Correct Health and program coordinators. ve (small and large, short and Care 2004;10:151–73. Four initial (21 peer educators and nti long term, male and female 33 students) and follow-up focus on prisoners) groups (31 peer educators, 36 students) at each site with trained peer educators and their students. Sirdifield C. Piloting a new role in U Focus group discussions with 2 Ge Health Trainer All prisoners 2b mental health – prison based health K health trainers (opportunistic ner trainers. J Ment Health Training sample). al Educ Pract 2006;1:15–22. he alt h/

13 Study C Methods He Nature of intervention/ Population/ setting Vali ou alt scheme dity nt h Scor ry to e pic s su pp ort

Stewart W. Evaluating peer social U Pre and post course questionnaires Ge Peer support 3 UK prisons. 3c care training in prisons. Prison Serv K and semi-structured interviews with ner Originally for older J 2011;195:43–6. stakeholders al prisoners but to include he those with learning alt disabilities, mental health h/ problems and prisoners with su physical and sensory pp disabilities. ort

Syed F, Blanchette K. Results of an Ca Interviews (21 prisoners: 4 PST Ge Peer Support Small women’s prison, 1c Evaluation of the Peer Support na members, 7 recipients, 10 non- ner n=78 at time of study. All Program at Grand Valley Institution da recipients); 12 staff. al were serving sentences of for Women. Ottawa, ON: em minimum 2 years and were Correctional Service of Canada; oti rated at ‘minimum’ or 2000. on ‘medium’ security levels. al/ me nta l he alt h, ps yc hol ogi cal su pp ort an d

14 Study C Methods He Nature of intervention/ Population/ setting Vali ou alt scheme dity nt h Scor ry to e pic s co un sel lin g

Syed F, Blanchette K. Results of an Ca Semi-structured interviews with Ge Peer Support Women’s prison in Canada. 2b Evaluation of the Peer Support na prisoners (n=29: 3 PST members, 7 ner N=56 at time of study. All Program at Joliette Institution for da recipients, 19 non-recipients) and al were serving sentences of Women. Ottawa, ON: Correctional staff (n=19) em minimum 2 years and were Service of Canada; 2000. oti rated at ‘minimum’ or on ‘medium’ security levels. al/ me nta l he alt h, ps yc hol ogi cal su pp ort an d co un sel lin g. Taylor S. New South Wales Prison A Pre (n=491)-post (n=458) HI Peer education New South Wales 3b

15 Study C Methods He Nature of intervention/ Population/ setting Vali ou alt scheme dity nt h Scor ry to e pic s HIV Peer Education Program. us questionnaire with prisoners. V Correctional Centres. 90% Sydney: Department of Corrective tra ‘Random’ surveys conducted with pre of inmates had been in other Services Australia; 1994 lia staff and prisoners. ve correctional centres. Review of the training and the nti programme materials on The Learning Ladder Ltd. U Focus groups comprising of 3 En Peer mentoring Reading YOI. Small prison 3c Mentoring for Progression: Peer K mentors. abl for young offenders aged Mentoring in a YOI. HMYOI ing 18-21 years. Reading; 2010 pri so ner s to rea ch “fu ll pot ent ial ” e.g . by gai nin g qu ali fic ati on s. Wright KN, Bronstein L. Creating U Telephone interviews/surveys- 17 Ge Prison hospice volunteers Dying prisoners in 14 2c decent prisons: a serendipitous S questions lasting 45 mins on ner prison hospices in the USA finding about prison hospice. J A average. In total,14 respondents al Offender Rehabil 2007;44:1–16. from the prison hospice unit; 5 he

16 Study C Methods He Nature of intervention/ Population/ setting Vali ou alt scheme dity nt h Scor ry to e pic s social workers, 3 chaplains, 2 health alt Wright KN, Bronstein L. administrators, 2 nurses, 1 clinical h/ Organizational analysis of prison psychologist, 1 nonprofessional su hospice. Prison J 2007;87:391–407. correctional staff member. pp ort

17