A Systematic Review of the Attributes and Outcomes of Peer Work and Guidelines for Reporting Studies of Peer Interventions
Abstract
Objectives:
The purpose of this review was to describe key attributes and outcome measures reported in controlled trials of peer work, identify outcome measures likely to report significant change as a result of peer work, assess the quality of reporting, and formulate guidelines for the design and reporting of future trials.
Methods:
A systematic review was undertaken of randomized and nonrandomized controlled trials of peer work published since 1995. A content analysis identified reported program attributes in seven areas. Outcome measures were compared with results to identify measures most likely to report a significant difference as a result of peer work. Descriptions of program attributes were rated with respect to how clearly they were specified by authors.
Results:
A total of 37 studies were included. Program attributes varied widely, particularly the services that peers delivered and the outcomes measured. Outcome measures were limited to measures of individual clinical improvement and recovery rather than social and structural impacts. Outcomes that more often showed significant differences as a result of peer work were patient activation, self-efficacy, empowerment, and hope. Gaps in reporting of the attributes of peer work programs were identified and used to formulate guidelines for the design of future trials.
Conclusions:
Lack of attention to fidelity to core peer work principles and aims in the design and reporting of effectiveness trials limits the utility of research to policy and practice. The proposed guidelines will help future researchers to capture the unique value of peer work for individual and systemic change.
The concept of peer work, the provision of support by people who have experienced mental distress to others with similar experiences, has emerged as an alternative to traditional expert-patient relationships (1). Qualitative studies of peer work have emphasized its value for personal empowerment and recovery (2,3); however, inclusion of peer work in traditional mental health services has resulted in increased scrutiny of the effectiveness of such interventions.
The evolving identity of peer work is reflected in the growing distinction between peer-delivered services and peer support (1). Davidson and colleagues (1) suggested that some programs are best recategorized as traditional services delivered by peers rather than as “peer support.” Descriptive studies of case management programs have demonstrated similarities in the way peers and nonpeers deliver case management (1), supporting the need for peer work frameworks that prevent peer workers from reenacting traditional “helping” relationships (4).
Distinct from the employment of peers as providers of conventional services (1), peer support is “a system of giving and receiving help founded on key principles of respect, shared responsibility and mutual agreement of what is helpful” (4). Peer support practitioners work relationally to understand their own and others’ perspectives and patterns and to support and challenge each other toward personal growth and change (4), mirroring the features of naturally occurring peer support relationships (5). This “two-way interaction,” “mutuality,” or “reciprocity” is frequently described as a key principle of peer support (4,6,7).
Peer work that more closely reflects natural peer relationships may assist in achievement of individual recovery outcomes (7). Relationships that involve mutual giving and receiving of support or that involve more provision than receipt of support are likely to result in more benefit (7). Nonetheless, critiques of reciprocity in some of the peer work literature suggest challenges to these principles when peers are employed in clinical settings (8,9). For the purposes of this review, we will consider peer work as a whole while acknowledging the diversity of peer work approaches (10).
The literature reflects more agreement on the aims of peer work (10,11). A key aim of both peer provider and peer support roles is the “the instillation of hope through positive self-disclosure” (11). A recent study working toward the development of a peer specialist fidelity measure proposed the following aims of peer specialist roles: help reduce isolation, focus on strengths, increase access to services, serve as a role model, increase clients’ participation in their own illness management, and share recovery story (12). Although well documented in qualitative studies, these aims are often not specified in the reporting of quantitative peer work trials (10,12)
Reviews of studies of peer work effectiveness suggest that peer workers are at least no worse than clinicians in achieving a range of clinical outcomes (13–15). Peer work has demonstrated effectiveness for recovery-related outcomes, such as feelings of hope, empowerment and agency, self-esteem, self-efficacy, self-management of difficulties, and social inclusion (13–15). Peer workers have been found to be helpful in engaging service users with complex needs and those who may be reluctant to use services (16,17). Despite these findings, few studies have addressed issues of fidelity to core peer work principles and aims, making comparisons of peer programs difficult (10,13).
Although recent studies pay more attention to fidelity (12,18) and meaningful outcomes (19), the wide range of measures used reflects a lack of agreement in the field. Lloyd-Evans and colleagues (13) questioned the mandatory implementation of peer work because of the lack of conclusive randomized trials in the field while acknowledging the challenges of evaluating such “complex interventions” (13,14). Because responses to the complex challenges faced by people experiencing mental health problems may represent a “bricolage” (20), so too must peer work research be designed to capture the complex value of peer work as a resource for personal and social change.
Using content analysis of published randomized controlled trials (RCTs) evaluating peer work, this study aimed to describe key attributes and outcome measures reported in controlled trials of peer work, to identify outcome measures likely to report significant change as a result of peer work, to assess the quality of reporting, and to formulate guidelines for the design and reporting of future trials.
Methods
A search strategy was devised on the basis of the following inclusion criteria: studies testing face-to-face peer interventions between persons diagnosed as having mental disorders, including co-occurring substance use disorders; studies of persons demonstrating symptomatology of mental disorders identified through standardized screening measures; RCTs or controlled trials involving equivalent sample groups; and peer-reviewed studies published in English from 1995 onwards, because previous reviews included no studies prior to 1995 that met our inclusion criteria.
Studies were excluded in which peer-delivered services were a component of a broader intervention model and the study design did not allow the effect of the peers to be isolated, the only mode of contact between peers was online or telephone, the sample group included individuals with a primary diagnosis of substance use disorder, or interventions were delivered in educational settings.
A total of 2,950 papers were identified via searches of PsycINFO, MEDLINE, and Embase databases (N=2,941) and ancestry searching (N=9) (that is, screening of reference lists in included or seminal papers on the topic). [A list of search terms is included in an online supplement to this article. A PRISMA diagram shows the process of screening and excluding studies.] A total of 336 duplicates were removed, leaving 2,605 unique results. After the titles and abstracts of these results were screened, a further 2,526 papers were excluded because they did not meet the inclusion criteria. Ten percent of results were randomly selected for double screening by the second author, with no discrepancies found in assessment of the inclusion or exclusion criteria. The full text was considered for 79 studies. In total, 37 studies, reported in 40 papers, met the inclusion criteria. [The PRISMA diagram in the online supplement includes reasons for exclusion at full-text screening.]
Basic content analysis, whereby descriptions of key attributes provided by authors were coded and the frequency of each code summarized in descriptive statistics across the data set (21), was conducted of peer work programs in completed studies (N=33) and study protocols (N=4). Codes were grouped thematically across the following program attributes: setting, definition of peer, peer control of the service, characteristics of service users, the nature of the services provided by peer workers, the training and supervision peer workers received, and what outcome measures were used. In addition, descriptions were given a rating based on how well the attribute was specified. [The criteria used to assess whether an attribute was fully specified (FS), partially specified (PS), or unspecified (US) are included in the online supplement.]
Results
Below is a systematic account of the content and quality of reported descriptions of peer program attributes. The included studies are listed in Table 1 (8,17,19,22–59), as well as ratings based on the degree of detail provided in descriptions. The content of the descriptions are included in Table 2.
| Study | Participants | Design | Key findings | Setting | Definition of peer | Peer control | Service user characteristics | Services provided | Training and supervision |
|---|---|---|---|---|---|---|---|---|---|
| Barbic et al., 2009, Canada (22) | Adults ages 18–60, who had used ACT services for >6 months and met DSM-IV criteria for schizophrenia, schizoaffective disorder, schizophreniform disorder, delusional disorder, or bipolar disorder | Superiority RCT; single blind; 33 participants randomly assigned to control intervention group or 12-week recovery workbook training in addition to usual treatment | Participation in the intervention group was associated with positive change in perceived levels of hope, empowerment, and recovery but not in QOL. | PS2 | PS | FS | PS1 | PS | US |
| Boevink et al., 2016, Netherlands (23) | Individuals with severe mental illness | Superiority waitlist RCT; 163 participants randomly assigned to intervention plus TAU versus TAU only | Intervention was associated with increased mental health confidence, less self-reported symptoms, lower level of need for care, and reduced risk of institutional residence. TREE participants had significantly lower values on the loneliness scale than nonparticipants. | PS2 | PS | PS | PS1 | FS | PS |
| Bright et al., 1999, USA (24) | Ages 18–60 with moderate to severe depressive symptoms | Noninferiority RCT; 98 adults randomly assigned to CBT or MS group facilitated by therapists or consumer-providers | Consumer-providers were as effective as professionals in reducing depressive symptoms in both groups; however, after treatment, more participants in professionally led CBT group were classified as nondepressed. | PS1 | PS | US | PS1 | FS | FS |
| Cabassa et al., 2015, USA (25) | Adult English or Spanish speakers with a diagnosis of a serious mental illness and BMI ≥25 receiving supportive housing services at the study sites | Hybrid superiority RCT and mixed-methods implementation study; 300 participants in peer- led, healthy lifestyle intervention group or in TAU | Results not found in literature search. Article describes study protocol only. | PS2 | PS | PS | PS1 | PS | PS |
| Chinman et al., 2013, USA (26) | Veterans with primary axis 1 psychiatric disorder and recent history of prolonged or frequent hospital admissions | Superiority RCT; 282 veterans randomly assigned to peer specialists or TAU. | Patients in the peer specialist group improved significantly more on activation compared with those receiving TAU. No other significant differences were found. | PS1 | PS | PS | PS2 | PS | PS |
| Clarke et al., 2000, USA (27) | Adults with “chronic” mental illness | Noninferiority RCT; 163 participants randomly assigned to one of two ACT teams (consumer-staffed or nonconsumer-staffed) or TAU | First psychiatric hospitalization occurred earlier for nonconsumer-staffed ACT participants than for those in consumer-staffed ACT. | FS | PS | PS | PS1 | PS | US |
| Cook et al., 2012, USA (28); Jonikas et al., 2013 (29) | Adults with severe mental illness on the basis of diagnosis, duration, and level of disability | Superiority RCT; 519 participants randomly assigned to 8-week program versus waitlist | WRAP participants reported significantly greater improvement in symptoms, hopefulness, and QOL; receipt of WRAP led to significantly greater propensity to engage in patient self-advocacy behaviors. | PS2 | PS | PS | PS2 | FS | PS |
| Cook et al., 2012 (30); Pickett et al., 2012, USA (31) | Adults with severe mental illness based on diagnosis, duration, and level of disability | Superiority RCT; 428 participants randomly assigned to BRIDGES (intervention condition) or a TAU waitlist | Intervention participants reported significantly greater improvement in overall recovery, as well as on subscales measuring personal confidence and tolerable symptoms, and significantly greater improvement in hopefulness. They also experienced significant increases in overall empowerment, empowerment–self-esteem, and self-advocacy–assertiveness and maintained these improved outcomes over time. | PS2 | PS | PS | PS1 | PS | PS |
| Cook et al., 2013, USA (32) | Adults with serious mental illness | Noninferiority RCT; 143 individuals assigned to WRAP or to a nutrition education course | Compared with the control group, WRAP participants reported significantly greater reduction over time in service use and service need. Participants in both groups improved significantly over time in symptoms and recovery outcomes. | PS1 | PS | PS | PS1 | FS | PS |
| Craig et al., 2009, UK (33) | Adult clients of assertive outreach team with severe mental illness and history of poor engagement | Superiority RCT; 45 participants randomly assigned to assertive outreach incorporating consumer-providers as HCAs or case management and assertive outreach | Clients allocated to the HCAs were more engaged with treatment, demonstrated higher levels of participation in structured social care activities, and had significantly fewer unmet needs. | PS1 | FS | PS | PS2 | PS | PS |
| Davidson et al., 2004, USA (34) | Adults who were receiving outpatient care at state-run community mental health centers | Noninferiority RCT; 260 participants randomly assigned to a peer volunteer (consumer) with an allowance for recreational activities, a nonconsumer peer with the same allowance, and a peer volunteer (consumer) with no allowance | Differences were noted only when a participant's degree of contact with the peer was considered. Participants with a nonconsumer peer improved social functioning and self-esteem when meeting with their partners, but for those with a consumer peer, these measures improved only when they did not meet. | PS2 | FS | PS | PS1 | PS | PS |
| Druss et al., 2010, USA (35) | Adults with a severe mental illness receiving mental health services who had ≥1 chronic general medical conditions | Superiority RCT; 80 consumers randomly assigned to a peer-led intervention to improve self-management of general medical conditions or to TAU | Significantly greater improvement was seen among intervention participants in patient activation and in rates of having ≥1 primary care visits. Small (nonsignificant) effects observed for physical health–related QOL, physical activity, and medication adherence. | PS2 | FS | PS | PS2 | FS | PS |
| Dumont and Jones, 2002, USA (36) | Adults with DSM-III-R diagnoses and history of substantial hospital stays | Superiority RCT; 265 participants randomly assigned into having or not having access to a “crisis hotel” | At 12 months, the experimental group had better healing outcomes, levels of empowerment, shorter hospital stays, and fewer hospital admissions. | PS1 | FS | PS | PS2 | PS | US |
| Eisen et al., 2012, USA (37) | Adults veterans with ≥1 psychiatric diagnoses who received mental health services at the participating site in the preceding 12 months | Noninferiority RCT; 240 participants randomly assigned to a recovery-oriented peer-led group (Vet-to-Vet), a clinician-led recovery group, or TAU | No statistically significant differences in improvement were noted between the groups. | PS2 | PS | FS | FS | FS | PS |
| Frost et al., 2012, USA (38) | Persons invited who had a significant hoarding problem, were not currently receiving treatment, and could meet scheduling requirements for the study | Superiority waitlist control trial; 43 participants randomly assigned to treatment or a waitlist | Intervention participants showed significant improvement on all measures compared with those on the waitlist. | US | PS | PS | FS | PS | FS |
| Hunkeler et al., 2000, USA (39) | Primary care patients diagnosed as having major depressive disorder or dysthymia and given a prescription for a selective serotonin reuptake inhibitor antidepressant | Superiority RCT; 302 participants randomly assigned to TAU, telehealth care, or telehealth care plus peer support; assessments conducted at baseline, 6 weeks, and 6 months | Adding peer support to telehealth care did not improve the primary outcomes. | PS1 | PS | PS | PS1 | PS | PS |
| Jerome et al., 2012, USA (40) | Adults with serious mental illness receiving outpatient mental health services | Superiority RCT; 93 participants randomly assigned to group exercise or group exercise plus peer support | Results not found in literature search. Article describes study protocol only. | PS2 | PS | PS | PS1 | PS | FS |
| Letourneau et al., 2011, Canada (41) | Women with an Edinburgh Postnatal Depression Scale score >12 caring for an infant less than 9 months old | Superiority RCT; 60 participants randomly assigned to control or intervention groups | A significant difference between groups was observed for one of the two measures of maternal-infant interactions. Several other measures favored the control group, including mothers’ depressive symptoms and social support scores. | PS1 | FS | PS | PS2 | PS | PS |
| Li et al., 2014, Singapore (42); Chan et al., 2014, Singapore (43) | Adults with schizophrenia in a stable condition referred by their attending psychiatrist or center counselor at community psychiatric rehabilitation centers | Superiority RCT; 122 participants, randomly assigned to the intervention group or the control group | At 6-month follow-up, significant improvements were found in the intervention group participants' level of empowerment, perceived recovery, social support, and symptom severity. | PS2 | FS | PS | PS1 | PS | PS |
| Mahlke et al., 2017, Germany (19) | Adults with a primary diagnosis of schizophrenia and related disorders, affective disorders, or personality disorder; illness duration of >2 years | Multisite, parallel-arm superiority RCT; 216 patients randomly assigned to one-to-one peer support plus TAU over the course of 6 months, compared with TAU | Patients in the intervention group had significantly higher scores on self-efficacy at 6-month follow-up. | PS2 | FS | PS | PS1 | PS | PS |
| Rabenschlag et al., 2012, Switzerland (44) | Women and men of any age in any kind of psychiatric institution with various psychiatric disorders | Quasi-experimental superiority design (control group but no randomization) with repeated measures; 13 experimental groups (N=115) and 6 control groups (N=34) | Participants had significantly higher values in the dimension “recovery is possible” directly after the interventions but not 6 months later. | PS2 | PS | PS | PS1 | FS | PS |
| Rivera et al., 2007, USA (45) | Adults with a diagnosis of a psychotic or mood disorder on axis I and with ≥2 admissions in the past 2 years; discharged to care of hospital outpatient clinic | RCT; 255 participants randomly assigned to strengths-based intensive case management with or without consumer-provider assistance or to clinic-based care | Similar improvements across conditions in symptoms, health care satisfaction, QOL, and social network behavior. Peer-assisted care showed the greatest increase in contacts with consumer and professional staff. | PS1 | PS | PS | PS1 | PS | PS |
| Robinson et al., 2010, Australia (46) | Young people ages 15–24 being discharged from a specialist first-episode psychosis treatment center | 18-month superiority RCT | Results not found in literature search. Article describes study protocol only. | PS1 | PS | PS | PS2 | FS | FS |
| Rogers et al., 2007, USA (47) | Adults with serious mental illness; DSM axis I or II diagnosis | Superiority RCT; 1,827 participants randomly assigned to COSP or traditional mental health services | Overall, a very modest increase in personal empowerment was seen. | PS2 | PS | PS | PS1 | PS | US |
| Rosenblum et al., 2014, USA (48) | Adults with a DSM-IV diagnosis of mental illness and a history of substance misuse attending a mental health or dual-diagnosis facility who were interested in the intervention group as an aftercare program | Superiority RCT; 203 substance-misusing clients randomly assigned to a dual-focus 12-step group (DTR) or to a waitlist control group | Compared with the control group, DTR participants used alcohol and any substances on fewer days. DTR participants were also more likely to rate themselves as experiencing better mental health and fewer substance use problems. | PS2 | PS | PS | PS1 | FS | US |
| Rowe et al., 2007, USA (17) | Adults with severe mental illness who had criminal charges in the 2 years before study enrollment | 2×3 prospective longitudinal, superiority RCT with two levels of intervention | The experimental group showed significantly reduced alcohol use compared with the control group. Alcohol use decreased over time in the experimental group and increased in the control group. | PS1 | PS | PS | PS2 | FS | PS |
| Rüsch et al., 2014, Switzerland (49) | Adults with ≥1 self-reported current DSM-IV axis I or II disorders and at least a moderate level of self-reported disclosure-related distress | Pilot superiority RCT; 100 participants assigned to the intervention group or TAU | The intervention had no effect on self-stigma or empowerment, but positive effects were noted on stigma stress, disclosure-related distress, secrecy, and perceived benefits of disclosure. | PS2 | PS | PS | FS | FS | PS |
| Salzer et al., 2016, USA (50) | Adults with a schizophrenia spectrum or affective disorder who identified ≥3 needs, recruited from mental health centers | Superiority RCT; 100 participants randomly assigned to be contacted by a certified peer specialist or to TAU | No differences were found in repeated-measures analyses. Post hoc analyses showed some positive results for those in the CIL condition. More than half of CIL participants described obtaining substantive support in ≥1 areas, and almost half of these efforts resulted in some tangible new resource. | PS1 | PS | FS | PS1 | FS | PS |
| Segal et al., 2011, USA (51) | New CMHA clients | Superiority RCT; 139 new clients randomly assigned to CMHA versus CMHA plus COSP | Significant changes favoring the CMHA-only condition were noted in social integration, personal empowerment, and self-efficacy. | PS1 | PS | PS | PS1 | US | PS |
| Segal et al., 2013, USA (52) | New CMHA clients accepted for service under California medical necessity criteria | Superiority RCT; 505 participants randomly assigned to regular CMHA services or to combined SHA and CMHA | The sample with combined services showed greater improvements in personal empowerment, self-efficacy, and independent social integration. Hopelessness and symptoms dissipated more quickly and to a greater extent in the combined condition than in the CMHA-only condition. | FS | PS | PS | PS1 | PS | US |
| Sells et al., 2006, USA (53); Sells et al., 2008, USA (54) | Adults with a primary diagnosis of severe mental illness and treatment disengagement | Noninferiority RCT; 137 participants randomly assigned to peer-based versus regular case management | Participants reported higher positive regard, understanding, and acceptance from peer at 6 months. No differences were noted at 12 months. Invalidation from peer providers was linked to improved QOL and fewer obstacles to recovery at 6 months but not at 12 months, an association that was not found for clients who experienced invalidation from regular providers. | PS2 | FS | PS | PS2 | PS | FS |
| Simpson et al., 2014, UK (55) | Adults diagnosed as having mental illness who were approaching discharge or extended leave from an inpatient unit | Pilot superiority RCT with economic evaluation; 46 participants randomly assigned to peer support plus TAU or to TAU alone | No statistically significant benefits were noted for peer support on the primary or secondary outcome measures. | PS1 | US | PS | PS1 | PS | US |
| Sledge et al., 2011, USA (56) | Adults with a diagnosis of schizophrenia, schizoaffective disorder, psychotic disorder not otherwise specified, bipolar disorder, or major depressive disorder who were admitted to an inpatient unit; ≥2 psychiatric hospitalizations in the past 18 months | Superiority RCT; 74 participants were randomly assigned to TAU or peer mentor and TAU | Participants assigned a peer mentor had significantly fewer rehospitalizations and fewer hospital days. | PS1 | FS | PS | PS1 | PS | PS |
| Solomon and Draine, 1995, USA (57) | Adults with diagnosis of a major mental illness and significant recent treatment history and disability | Noninferiority RCT; 96 participants randomly assigned to case management by peers or nonpeers | No significant between-group differences were found. | PS2 | PS | PS | PS2 | PS | PS |
| Uhm et al., 2016, USA (58) | Adults identified by mental health professionals as having hoarding behaviors who were interested in treatment for hoarding | Noninferiority RCT; 300 participants randomly assigned to CBT or a peer-led self-help group. | Results not found in literature search. Article describes study protocol only. | PS1 | PS | PS | PS1 | PS | PS |
| van Gestel-Timmermans et al., 2012, the Netherlands (59) | Adults with self-reported psychiatric problems and experience of disruptive periods from which they were recovering | Superiority RCT; 333 people randomly assigned to a peer-run course or a control group | The peer-run course had a significant and sustained positive effect on empowerment, hope, and self-efficacy beliefs but not on QOL and loneliness. | US | PS | FS | PS1 | FS | PS |
| Wrobleski et al., 2015, Canada (8) | Adults living with persistent mental illness and receiving services from a community health team | Noninferiority mixed-methods pilot RCT with qualitative interviews; 15 participants randomly assigned to a group with an OT plus a PSW or a group with an OT plus an MHW | Both groups improved from baseline to 6 months; the PSW group did not improve more than the MHW group. | US | PS | PS | PS2 | PS | PS |
TABLE 1. Studies (N=37) included in a systematic review of the attributes and outcomes of peer worka
| Attribute | N | % |
|---|---|---|
| Setting | ||
| Outpatient or community mental health agency | 22 | 59 |
| Urban | 12 | 32 |
| Case management | 9 | 24 |
| Consumer-operated mental health agency | 8 | 22 |
| Inpatient | 7 | 19 |
| Psychosocial services | 7 | 19 |
| Publicly funded | 7 | 19 |
| Community based | 6 | 16 |
| Residential | 5 | 14 |
| Assertive community treatment or outreach | 5 | 14 |
| Nonprofit organization | 4 | 11 |
| Crisis services | 3 | 8 |
| Suburban | 3 | 8 |
| Rural | 3 | 8 |
| Primary care | 2 | 5 |
| Center for independent living | 1 | 3 |
| Fee for service | 1 | 3 |
| Veterans Health Administration | 1 | 3 |
| Definition of peer | ||
| Diagnosis | 15 | 41 |
| “In recovery” | 14 | 38 |
| Employed (paid for peer work) | 13 | 35 |
| Peer role | 12 | 32 |
| Prior peer qualifications | 10 | 27 |
| Service use | 10 | 27 |
| Specified characteristics | 9 | 24 |
| Peer role experience | 8 | 22 |
| Nonpeer skills or qualifications | 5 | 14 |
| Volunteer | 3 | 8 |
| Peer control | ||
| Clinician operated | 17 | 46 |
| Shared responsibility | 13 | 35 |
| Consumer operated | 5 | 14 |
| Service user characteristics, inclusion criteria | ||
| Adults | 23 | 62 |
| Severe, serious, chronic, or major mental illness | 16 | 43 |
| Receiving services in community | 14 | 38 |
| DSM disorder, axis not specified | 13 | 35 |
| Functional impairment | 8 | 22 |
| Inpatient admissions or at risk of hospitalization | 7 | 19 |
| DSM axis I diagnosis | 7 | 19 |
| Treatment disengagement | 2 | 5 |
| Positive screen for mental disorder | 2 | 5 |
| Military veteran | 2 | 5 |
| Comorbid general medical condition | 2 | 5 |
| Young person | 1 | 3 |
| Emergency service use | 1 | 3 |
| Self-reported mental distress or disorder | 1 | 3 |
| Forensic history | 1 | 3 |
| Comorbid substance use disorder | 1 | 3 |
| Hoarding behaviors | 1 | 3 |
| New mother | 1 | 3 |
| Service user characteristics, exclusion criteria | ||
| Inadequate language skills | 19 | 51 |
| Primary substance use disorder | 10 | 27 |
| Low premorbid IQ or other cognitive impairment | 9 | 24 |
| Acutely unwell | 4 | 11 |
| Receiving treatment | 4 | 11 |
| Risk to self | 4 | 11 |
| Risk to others | 3 | 8 |
| Primary personality disorder | 3 | 8 |
| Comorbid substance use disorder | 3 | 8 |
| In prison | 2 | 5 |
| Pregnant or caring for children | 1 | 3 |
| Organic disorder as cause of psychosis | 1 | 3 |
| Psychotic illness | 1 | 3 |
| Unipolar depression or anxiety | 1 | 3 |
| Physical health concerns or impairment | 1 | 3 |
| Services provided | ||
| Group | 22 | 59 |
| Individual | 17 | 46 |
| Peer education | 17 | 46 |
| Skills training | 14 | 38 |
| Peer support or mutual support | 14 | 38 |
| Recovery education and planning | 13 | 35 |
| Sharing lived experience | 11 | 30 |
| Socialization | 11 | 30 |
| Engagement with services | 9 | 24 |
| Peer counseling, coaching, or mentoring | 8 | 22 |
| Case management | 8 | 22 |
| Self-advocacy | 8 | 22 |
| Advocacy | 7 | 19 |
| Practical support | 7 | 19 |
| Information | 7 | 19 |
| Psychoeducation | 4 | 11 |
| Mediation | 3 | 8 |
| Material resources | 3 | 8 |
| Crisis support | 2 | 6 |
| Cognitive-behavioral therapy | 2 | 6 |
| Helping clinical staff | 1 | 3 |
| Training and supervision | ||
| Peer-specific training | 22 | 59 |
| Non–peer-specific training | 13 | 35 |
| Clinical supervision | 12 | 32 |
| Peer supervision | 5 | 14 |
TABLE 2. Attributes of peer programs reported in 37 studies included in the review
Setting
Peer programs were delivered in a range of settings both consumer operated (N=8) and those linked to outpatient (N=22), inpatient (N=7), and residential (N=5) services. Of the studies that specified, most services were in urban settings (N=12). Studies varied greatly in the detail provided about the setting, many offering inadequate description of the program’s funding source, the demographic characteristics and size of the population served, the services provided by the agency, or its staffing profile.
Definitions of Peers
Descriptions of peers most commonly referred to their having a diagnosis of a mental disorder (N=15), being “in recovery” (N=14), or having used mental health services (N=10). References to peers’ capacity to manage their mental health were more frequent in recent studies (28,43,56,59). Although most studies included some description of peers’ lived experience and training, few specified whether peers were employed on a paid (N=13) or voluntary (N=3) basis.
Consumer Control of Service
Although it was often difficult to determine the degree of peer control in the operation of peer programs, most studies were conducted in clinically operated services where peer participation in the running of the program was limited or not described (N=17). An additional group of studies described the responsibility for operations as being shared between clinicians and peers (N=13).
Service Users
When specified, most programs targeted individuals over age 18 (N=23); only one program worked with those under 18. Only one study of new mothers was restricted to female participants. The most commonly used descriptor of participants’ mental health concerns was “severe mental illness” (N=16) or meeting DSM criteria for a mental disorder (N=20). Only three studies targeted those who self-identified as having mental health concerns (N=1) or those who screened positive for symptoms of mental disorders (N=2).
Other common descriptors of service users included persons accessing community mental health services (N=14) or those admitted or at risk of admission to inpatient settings (N=7). Two studies targeted people who were disengaged from services.
Although most studies did not target specific groups, selected studies targeted people with comorbid substance use disorders (N=1) or general medical conditions (N=2), veterans (N=2), persons with forensic histories (N=1), new mothers (N=1), and those with hoarding issues (N=1).
The most common exclusion criterion was the inability to speak, read, or write English or the dominant language of the country where the study was based (N=19). Only one study specified inclusion of individuals who spoke another community language. A number of studies excluded those with primary substance use disorders (N=10) or co-occurring substance use issues (N=3), those with cognitive or intellectual impairments (N=9), and those with primary personality disorders (N=3). Some excluded those acutely unwell (N=4) or who were deemed to present a risk to themselves (N=4) or others (N=3).
Services Delivered
The included studies described peers providing a range of services along the continuum from services able to be provided only by peers, such as peer education (N=17), peer support (N=14), and peer mentoring (N=8), to those typically delivered by clinicians, such as case management (N=8), psychoeducation (N=4), and cognitive-behavioral therapy (N=2). Several studies described peers’ promotion of individuals’ engagement in services (N=9). Less than a third of studies (N=11) explicitly referred to peers sharing their lived experience; however, several studies referred to peers’ provision of skills training (N=14), recovery education (N=13), and promotion of self-advocacy (N=8). Services varied widely in their duration, and slightly more often were provided in a group (N=22) rather than an individual (N=17) format.
Training and Supervision
Most studies (N=22) referred to peers as being engaged in some form of peer-specific training prior to their role, but a smaller proportion of these (N=10) recruited peers who had completed certified peer training. These studies tended to be more recently published. It was often difficult to determine whether peer-specific training was delivered by peer workers, but more commonly it appeared to be delivered by clinicians. Some studies reported peers’ receipt of general training (N=13) in preparation for their roles. Ongoing supervision of peers, when reported, was more often delivered by clinicians (N=12) than by other peer workers (N=5).
Outcome Measures
Outcome measures were the only attribute of peer programs that were fully specified in all studies. Most studies used a combination of both clinical and recovery-related outcomes. Some studies measured the effectiveness of peer workers in engaging consumers. The outcome measures used by all studies and their results are summarized in Table 3 (8,17,19,22–24,26–39,41–45,47–52,54–57,59).
| Study | Symptom severity | Quality of life | Social inclusion | General functioning | Empowerment | Service use | Hope | Recovery | Substance use | Self-efficacy | Hospital admission | Service engagement | Medication adherence | Social disadvantage | Forensic issues | Patient activation | Service satisfaction | Working alliance | Physical health | Cognitive functioning | Community access | Family burden |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Barbic et al., 2009 (22) | 0 | 1 | 1 | 1 | ||||||||||||||||||
| Boevink et al., 2016 (23) | 1 | 0 | 1 | 1 | 0 | 1 | 1 | 1 | ||||||||||||||
| Bright et al., 1999 (24) | –1 | 0 | ||||||||||||||||||||
| Chinman et al., 2013 (26) | 0 | 0 | 0 | 0 | 1 | |||||||||||||||||
| Clarke et al., 2000 (27) | 0 | 0 | 1 | 0 | 0 | 0 | 0 | |||||||||||||||
| Cook et al., 2012 (28); Jonikas et al., 2013 (29) | 0 | 1 | 0 | 0 | ||||||||||||||||||
| Cook et al., 2012 (30); Pickett et al., 2012 (31) | 1 | 1 | 1 | |||||||||||||||||||
| Cook et al., 2013 (32) | 1 | 1 | 0 | 1 | 1 | 1 | ||||||||||||||||
| Craig et al., 2009 (33) | 0 | 0 | 0 | 1 | 1 | 0 | ||||||||||||||||
| Davidson et al., 2004 (34) | 0 | 0 | 0 | 0 | 0 | 0 | ||||||||||||||||
| Druss et al., 2010 (35) | 1 | 1 | 1 | 1 | ||||||||||||||||||
| Dumont and Jones, 2002 (36) | 0 | 1 | 0 | 1 | 1 | |||||||||||||||||
| Eisen et al., 2012 (37) | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | |||||||||||||
| Frost et al., 2012 (38) | 1 | 1 | ||||||||||||||||||||
| Hunkeler et al., 2000 (39) | 0 | 0 | 0 | |||||||||||||||||||
| Letourneau et al., 2011 (41) | –1 | –1 | –1 | 0 | ||||||||||||||||||
| Li et al., 2014 (42); Chan et al., 2014 (43) | 1 | 0 | 1 | 0 | 1 | 0 | 1 | 0 | 0 | |||||||||||||
| Mahlke et al., 2017 (19) | 0 | 0 | 0 | 1 | ||||||||||||||||||
| Rabenschlag et al., 2012 (44) | 1 | |||||||||||||||||||||
| Rivera et al., 2007 (45) | 0 | 0 | 0 | 0 | 0 | 0 | ||||||||||||||||
| Rogers et al., 2007 (47) | 0 | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | ||||||||||||
| Rosenblum et al., 2014 (48) | 1 | 0 | 1 | 0 | 0 | |||||||||||||||||
| Rowe et al., 2007 (17) | 1 | 0 | ||||||||||||||||||||
| Rüsch et al., 2014 (49) | 1 | 0 | 0 | |||||||||||||||||||
| Salzer et al., 2016 (50) | 0 | 0 | 0 | 0 | 0 | |||||||||||||||||
| Segal et al., 2011 (51) | 1 | 1 | 1 | 1 | 1 | |||||||||||||||||
| Segal et al., 2013 (52) | 0 | –1 | –1 | 0 | –1 | |||||||||||||||||
| Sells et al., 2008 (54) | 1 | 0 | 0 | 0 | 1 | |||||||||||||||||
| Simpson et al., 2014 (55) | 0 | 0 | 0 | 0 | ||||||||||||||||||
| Sledge et al., 2011 (56) | 1 | |||||||||||||||||||||
| Solomon and Draine, 1995 (57) | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | ||||||||||||
| van Gestel-Timmermans et al., 2012 (59) | 0 | 0 | 1 | 1 | 1 | |||||||||||||||||
| Wrobleski et al., 2015 (8) | 0 | |||||||||||||||||||||
| Total | 22 | 17 | 15 | 14 | 13 | 13 | 10 | 9 | 9 | 8 | 7 | 5 | 5 | 5 | 4 | 3 | 3 | 3 | 2 | 1 | 1 | 1 |
| Significant difference favoring peer intervention | 7 | 2 | 4 | 2 | 8 | 3 | 6 | 4 | 2 | 5 | 3 | 1 | 1 | 1 | 0 | 2 | 0 | 1 | 1 | 0 | 0 | 0 |
| No significant difference | 13 | 15 | 9 | 10 | 4 | 10 | 4 | 5 | 7 | 2 | 4 | 4 | 4 | 4 | 4 | 1 | 3 | 2 | 1 | 1 | 1 | 1 |
| Significance difference favoring control conditions | 2 | 0 | 2 | 1 | 1 | 0 | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| % of studies using this measure reporting significant difference favoring peer intervention | 32 | 12 | 27 | 14 | 62 | 23 | 60 | 44 | 22 | 63 | 43 | 20 | 20 | 20 | 0 | 67 | 0 | 33 | 50 | 0 | 0 | 0 |
TABLE 3. Results of studies of peer interventions included in this review, by outcome measureda
The measures most likely to report favorable outcomes as a result of peer work were patient activation (67% of studies using this measure), self-efficacy (63%), empowerment (62%), and hope (60%). Although commonly used, some measures were less likely to report a significant difference as a result of peer work, including symptom severity (32% of studies using this measure), quality of life (12%), social inclusion (27%), general functioning (14%), and service use (23%).
Guidelines for Future Research
On the basis of the findings of our first two research questions, some guidelines for future research are summarized in Table 4. First and most important, it is recommended that authors adhere to existing guidelines for the reporting of RCTs. Second, measurement of fidelity alongside measurement of effectiveness, using mixed-methods research designs, is warranted to establish the principles that guide effective peer programs. Rather than prescriptively defining the activities of peer workers through manualized interventions and inflexible delivery, peer work research should seek to both promote and measure programs’ fidelity to core principles. Fidelity might be improved by increasing access to peer-delivered training and supervision to monitor and improve role definition (60,61).
| Gaps identified in this review | Recommendations | Suggestions |
|---|---|---|
| Inadequate reporting of program attributes | Improved reporting of core features of setting, peer workers, participants, interventions, and support structures to allow for replication in a different setting or similar study | Authors to refer and adhere to CONSORT guidelines in reporting results of RCTsa |
| Inconsistent reporting of adherence to core peer work principles and tasks | Measure of fidelity to core peer support tasks | Use of mixed-methods research design to simultaneously report the nature of peer interventions provided, as well as results (for example, qualitative interviews with participants to assess fidelity to core peer support tasks). Use of existing peer fidelity instruments (12) to correlate fidelity with positive outcomes. Further development of peer fidelity instruments measuring adherence to peer principles |
| Lack of evidence supporting mechanisms of change of peer-delivered interventions | Testing the theoretical underpinnings of peer support | Exploration of correlation between fidelity to peer support principles and recovery outcomes. Further exploration of the relationship between shared lived experience, including the degree of shared experience, and recovery outcomes. Testing of established psychosocial theories thought to operate within peer work relationships |
| Inappropriate use of outcome measures in research evaluation of peer-delivered interventions | Agreement on outcome measures sensitive to peer work interventions in the short and long terms | Continued use of outcome measures that assess empowerment, hope, self-efficacy, patient activation, and illness management. Further testing of program attributes that predict better outcomes in other recovery-related areas (for example, social inclusion, quality of life, recovery). Measure such outcomes as program duration, additional qualifications of peer workers, peer work model used, activities, and setting. Increased use of outcome measures that evaluate the process of peer support (for example, working alliance and consumer satisfaction). Increased caution in reporting outcomes less relevant to the objectives of peer work (for example, symptom severity) |
| Lack of evaluation of system-level impacts of peer work | Development of measures and research designs to assess system-level impacts of peer work | Use of measures of service recovery orientation (66) (for example, Pillars of Recovery Service Audit Tool [66] and the Recovery Promotion Fidelity Scale [67]) to capture the impact of employment of peer workers within services on overall recovery orientation |
TABLE 4. Guidelines for reporting of future peer support research
Third, although recent qualitative studies have attempted to articulate the mechanisms of change within peer work (62,63), these must be correlated against measures of effectiveness to be validated. Sells and colleagues’ (54) investigation of the value of invalidation in peer work relationships is a rare but informative example of testing of the mechanisms of change referred to by peer support theorists. Salzer and Shear (64) identified the following concepts and theories that may be relevant to peer-delivered services: social support, experiential knowledge, the helper-therapy principle, social learning theory, and social comparison theory. Further testing of these theories might inform the development of fidelity measures to guide future peer program design and research (10).
Last, in addition to use of more appropriate individual outcome measures, more work is needed to capture the system-level impacts of peer work, such as recovery orientation, in traditional mental health settings (65–67).
Discussion
Attributes of Peer Work Reported in Peer Work Trials
Overall, included studies reflected the changing face of peer work (2). In role descriptions and specialist peer training, a transition from peer providers of traditional services to greater recognition of the specific skill set was evident (11). Despite evidence of a transition, the vast majority of services were provided in settings in which clinical staff exercised a degree of control over the services delivered. These findings are in line with results of a recent review of traditional mental health settings that found low participation rates of consumer staff in leadership roles (68). Further research is needed to determine whether consumer leadership in peer programs has an impact on fidelity to core peer work principles and aims (69).
The employment of peers in paid positions represents a challenge in maintaining the “peerness” of peer providers. Several studies (N=8) referred to services as “peer counseling,” “peer mentoring,” and “peer coaching,” which may indicate a shift toward more uneven relationships. Further investigation of the relationship between mutuality and recovery outcomes is needed to determine its importance in formal peer programs.
Despite research evidence demonstrating the superiority of peers in engaging persons reluctant to access services (17), only two studies targeted those who were disengaged from services, and several studies excluded those with more complex needs. The work of Sells and colleagues (54) regarding the role of invalidation suggests that peers may be in a unique position to challenge each other and thus may be underutilized if they are restricted from working with service users who have more complex conditions, such as those with self-harm or substance use issues.
Outcome Measures Used in Peer Work Research
The use of measures of clinical recovery (for example, symptom severity) to assess the effectiveness of peer work is problematic given that peers may aim to support individuals in living meaningful lives despite ongoing symptoms. As such, measures that capture subjective distress or perceived control of symptoms may be more appropriate and sensitive to change. Similarly, suggesting that peers are ineffective because of a lack of short-term differences in measures of quality of life, social inclusion, and functioning underestimates the complex nature of recovery. More long-term studies are needed to determine whether improvements in hope and confidence in self-advocacy, which frequently respond to peer interventions, are correlated with more substantive recovery outcomes (35,70).
Gaps in the Reporting of Peer Work Trials
Insufficient detail about the guiding principles of peer programs—beyond the fact that the programs are provided by peers—makes it difficult to draw conclusions about the relationship between fidelity to these principles and outcomes. As Davidson and colleagues (1) noted, “the fact that a person is in recovery from his or her own serious mental illness tells us little about how he or she functions in the role of service provider.” Some progress has been made in further defining peer specialist roles (11,12,18); however, fidelity to principles guiding these roles is yet to be measured in quantitative studies.
Limitations
Although we limited our review to RCTs or controlled trials involving equivalent sample groups, the limitations of these research designs with reference to peer work are well recognized (71). Many studies acknowledged limitations of small sample sizes (8,55,57). It is important to note that many studies excluded individuals with inadequate spoken language or literacy skills. Given the potential value of peer work for reducing social exclusion and bridging cultural differences, this represents a significant gap in our understanding of the value of peer work with these groups (6).
Conclusions
Lack of attention to core peer work principles and aims in the design and reporting of effectiveness trials limits translation to policy and practice. To better understand the value of peer work, further research is needed to validate the theorized mechanisms of change within peer relationships (10). The impact of providing peers with training and supervision delivered by other peers on the effectiveness of peer work interventions also requires further investigation. Outcome measures should be chosen to capture not just the value of peer work in promoting personal empowerment and hope but also systemic impacts, such as the recovery orientation of services (66).
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