Evaluation of a complex intervention (Engager) for prisoners with common mental health problems, near to and after release: study protocol for a randomised controlled trial

Introduction The ‘Engager’ programme is a ‘through-the-gate’ intervention designed to support prisoners with common mental health problems as they transition from prison back into the community. The trial will evaluate the clinical and cost-effectiveness of the Engager intervention. Methods and analysis The study is a parallel two-group randomised controlled trial with 1:1 individual allocation to either: (a) the Engager intervention plus standard care (intervention group) or (b) standard care alone (control group) across two investigation centres (South West and North West of England). Two hundred and eighty prisoners meeting eligibility criteria will take part. Engager is a person-centred complex intervention delivered by practitioners and aimed at addressing offenders’ mental health and social care needs. It comprises one-to-one support for participants prior to release from prison and for up to 20 weeks postrelease. The primary outcome is change in psychological distress measured by the Clinical Outcomes in Routine Evaluation-Outcome Measure at 6 months postrelease. Secondary outcomes include: assessment of subjective met/unmet need, drug and alcohol use, health-related quality of life and well-being-related quality of life measured at 3, 6 and 12 months postrelease; change in objective social domains, drug and alcohol dependence, service utilisation and perceived helpfulness of services and change in psychological constructs related to desistence at 6 and 12 months postrelease; and recidivism at 12 months postrelease. A process evaluation will assess fidelity of intervention delivery, test hypothesised mechanisms of action and look for unintended consequences. An economic evaluation will estimate the cost-effectiveness. Ethics and dissemination This study has been approved by the Wales Research Ethics Committee 3 (ref: 15/WA/0314) and the National Offender Management Service (ref: 2015–283). Findings will be disseminated to commissioners, clinicians and service users via papers and presentations. Trial registration number ISRCTN11707331; Pre-results.

My two main issues with the current draft of the manuscript are: -The primary outcome is psychological distress. This is the only outcome for which power calculations are provided. Given the scope of the intervention, why did the researchers decide to focus on this outcome in particular? -In my view the manuscript could be shortened considerably, without loss of information. A careful proofread for clarity of expression would also strengthen the manuscript. I would also encourage the authors to consider replacing the term "offender" with something less pejorative. Since the population of interest is adult males released from prison, not necessarily on parole, one might argue that use of the term "offender" in this context is somewhere between pejorative and inaccurate.
More specific comments follow. P. 5 line 5 "rates of 50-90%"presumably prevalence rates? Is this point, period or lifetime prevalence? p. 5 line 5 "trials are limited"it might be appropriate to cite here a recent systematic review documenting precisely this: Kouyoumdjian et al (2015). Am J Public Health, 105(4), e13-e33. P. 5 line 11 need a reference to support the statement about PTSD.
p. 5 line 16 clarify whether comorbidity refers to multiple mental illnesses, or co-occurrence of mental illness and substance use disorder, or both/either. p. 5 line 21 "in our previous study"more information is required and could be provided in a few wordsfor example was this a cross-sectional study of ### prisoners in the UK? p. 5 line 25is the SPCR study based in the UK? p. 6 line 15 note that there is also some international evidence regarding engagement with mental health services for ex-prisoners: see for example Thomas et al (2016). Psychological Medicine, 46(3), 611-621.
p. 6 line 49 it would be helpful to briefly explain WHY the primary outcome is psychological distress (rather than one or more of the secondary outcomes), either here or earlier in the Introduction.
p. 8 line 18 who determines that a mental health problem "is likely to be a problem for them again following their release", and how? p. 9 line 6 a web-based randomisation system is used to "ensure concealment" but if it is 1:1 potential participants may detect a pattern. Has block randomisation been considered? If not, why not? p. 10 line 16 "Outcome measure data will be collected at baseline"this seems contradictory.
The CORE-OM is the primary outcome measurewhat evidence exists for its reliability and validity? The entire trial hinges on this measure, so this is critical. p. 13 line 3 small typo: "follow-ups interviews" (remove "s") Table 2 lists some measures not identified as primary or secondary outcome measures (e.g., Trauma questionnaire). The primary and secondary outcome measures are also listed on page 10. Then the survey measures are listed again on page 13. Removal of significant redundancy/duplication such as this would substantially shorten the paper, without loss of information.
Health economic work appears to rely on self-reported health service use. It would be useful to cite recent evidence suggests that this can be valid in ex-prisoners: Carroll et al (2016). Health & Justice, 4:11; DOI: 10.1186/s40352-016-0042-x.
p. 14 line 48 assuming lifetime maintenance of short-term health gains seems incautious. Is this justifiable?
Consider a Figure depicting the study design. Is the primary analysis powered to accommodate inclusion of baseline measures as covariates a priori? Is the trial powered for the secondary outcomes?
Have the researchers considered the risk of contamination, and strategies to minimise this? If not, why not?
ISRCTN registration is noted in the Abstract but not the body of the manuscript. This information should be included in the body of the manuscript.

REVIEWER
Leah Hamilton Temple University Philadelphia PA, USA REVIEW RETURNED 19-Jul-2017

GENERAL COMMENTS
Overall the authors present a detailed protocol of an interesting and important study on offender mental health in the transition back into the community. Most of the "N/A" and "No" responses in the tick-box section of this review are due to the fact that this is a protocol not a completed study. However a few issues remain that ought to be addressed.

Selection bias issues:
The protocol should acknowledge and discuss the potential selection bias of 1. excluding the serious/enduring mental health problem population and 2. having only those 'willing to engage with treatment services and research procedures'. Of course, this is not to suggest that either individuals with serious mental health conditions need to be included or that participation should be mandatory. Rather it needs to be clearer why the eligibility criteria is what it is, how this may influence the outcomes, and whether anything can be done to statistically mitigate this bias.
3. Is there any justification for the intervention time-frame? It does appear to align with the RPI project, but there's no explanation given in text.
4. Are there arguments for the use of the various outcome measure instruments? For example, why is the Leeds Dependence Questionnaire used? There are a number of substance use disorder screeners available (e.g. the DAST-10) including those specifically designed for offender populations (TCU Drug Screen). Please justify the screener choice.
5. For the process evaluation, will any standardized measures be developed to measure implementation fidelity? Some basic questionnaires could be used to supplement the semi-structured interviews 6. Although it is difficult to develop an in-depth statistical analysis plan prior to data collection, the multi-institution nature of the study suggests that higher level effects should be considered in the analyses. Consider multi-level modelling using nesting within region, institution or practitioners.

Reviewer 1
Comment: In my view the manuscript could be shortened considerably, without loss of information. A careful proofread for clarity of expression would also strengthen the manuscript.
Response -we have attempted to shorten the manuscript, but due the the addtional infomation requested it has actually increased in size Comment: I would also encourage the authors to consider replacing the term "offender" with something less pejorative. Since the population of interest is adult males released from prison, not necessarily on parole, one might argue that use of the term "offender" in this context is somewhere between pejorative and inaccurate.
Response -The term offender has been replaced with a more appropriate term where applicable More specific comments follow.
Response -We have clarified in the text that this is point prevalence Comment: p. 5 line 5 "trials are limited"it might be appropriate to cite here a recent systematic review documenting precisely this: Kouyoumdjian et al (2015). Am J Public Health, 105(4), e13-e33.
Response -reference has been added and text slightly amended Comment: P. 5 line 11 need a reference to support the statement about PTSD.
Response -statement about PTSD has been removed as it is covered later in paragraph Comment: p. 5 line 13 note also recent evidence of high rates of self-harm after release from prison: Borschmann et al (2017). ANZ J Psychiatr, 51(3), 250-259.
Response -reference has been added Comment: p. 5 line 16 clarify whether comorbidity refers to multiple mental illnesses, or co-occurrence of mental illness and substance use disorder, or both/either.