The authors' have thoroughly addressed all comments. Congratulations on this important study.

Is the work clearly and accurately presented and does it cite the current literature?

Partly

If applicable, is the statistical analysis and its interpretation appropriate?

Not applicable

Are all the source data underlying the results available to ensure full reproducibility?

No source data required

Is the study design appropriate and is the work technically sound?

Yes

Are the conclusions drawn adequately supported by the results?

Yes

Are sufficient details of methods and analysis provided to allow replication by others?

Yes

Reviewer Expertise:

NA

We confirm that we have read this submission and believe that we have an appropriate level of expertise to confirm that it is of an acceptable scientific standard.

We have no additional comments. The authors have satisfactorily addressed the issues we had raised.

Is the work clearly and accurately presented and does it cite the current literature?

Yes

If applicable, is the statistical analysis and its interpretation appropriate?

Yes

Are all the source data underlying the results available to ensure full reproducibility?

Yes

Is the study design appropriate and is the work technically sound?

Yes

Are the conclusions drawn adequately supported by the results?

Yes

Are sufficient details of methods and analysis provided to allow replication by others?

Yes

Reviewer Expertise:

NA

We confirm that we have read this submission and believe that we have an appropriate level of expertise to confirm that it is of an acceptable scientific standard.

We are OK with the changes made by the authors and thank them for addressing each point diligently.  

Is the work clearly and accurately presented and does it cite the current literature?

Yes

If applicable, is the statistical analysis and its interpretation appropriate?

Yes

Are all the source data underlying the results available to ensure full reproducibility?

Yes

Is the study design appropriate and is the work technically sound?

Yes

Are the conclusions drawn adequately supported by the results?

Yes

Are sufficient details of methods and analysis provided to allow replication by others?

Yes

Reviewer Expertise:

NA

We confirm that we have read this submission and believe that we have an appropriate level of expertise to confirm that it is of an acceptable scientific standard.

This systematic review examines the criminal recidivism rates of prisoners internationally, with the aspiration that ‘the comparison of recidivism rates between countries and regions may provide useful information about relative effectiveness of different sentencing and rehabilitation policies’ (p.3). This is indeed an important and timely research endeavour given that the Ministry of Justice in England and Wales recently published the responses to a consultation on proposed changes to the proven reoffending rates it produces (see; Ministry of Justice, 2016 ¹ and 2017 ²) to ‘align the existing reoffending measure with those measures necessary for assessing progress against the rehabilitation reforms’ (Ministry of Justice, 2016 ¹, p.3). Furthermore, the production and use of data, such as recidivism rates that is often held by government departments is a major issue of democratic governance (Parsons, 2002 ³, p.145). This review updates findings from a previous one (Fazel & Wolf, 2015 ⁴), and expands the searches conducted from 20 to 50 countries with the largest prison populations.

Whilst recidivism rates do have the potential to be used as a standardised measure of prison performance and could be used to compare prisons nationally (and internationally), any choice of

outcome should reflect the purpose of prisons, and this is likely to vary internationally. There are, however, several drawbacks to using recidivism rates in this context;

• Recidivism rates underestimate the true amount (and cost) of crime in society, as a significant (but unknown) amount of crime is unreported/unsolved.

• Recidivism rates do not tell us anything about whether the new offence committed was more or less serious than the previous one. Therefore, they are a fairly crude measure of effectiveness.

• Recidivism rates only capture instances of failure and do not take into account successes.

• Recidivism rates do not reflect what we know about desistance theory (i.e. pathways out of crime often involve sidesteps and missteps, see McNeill & Schinkel, 2016 ⁵).

• Recidivism rates often do not tell us if the person was returned to custody, and are therefore limited in terms of calculating the cost of crime to society.

Comparisons between prison regimes internationally are fraught with difficulties; especially given recent changes in prison populations, policy and reporting practices. Additionally, what constitutes a crime can vary from one country to the next.

Notwithstanding any concerns as to the appropriateness of these comparisons, one of the main findings of this updated review is that researchers are still some way off being able to perform these comparisons; only 10 of the 50 countries reported recidivism rates for prisoners, and due to the heterogeneity in the type of figures produced it was not possible for the authors to produce a meta-analysis. A recidivism reporting checklist is proposed as a means of standardising how countries produce this statistical information and its adoption should be recommended.

Is the work clearly and accurately presented and does it cite the current literature?

Yes

If applicable, is the statistical analysis and its interpretation appropriate?

Yes

Are all the source data underlying the results available to ensure full reproducibility?

Yes

Is the study design appropriate and is the work technically sound?

Yes

Are the conclusions drawn adequately supported by the results?

Yes

Are sufficient details of methods and analysis provided to allow replication by others?

Yes

Reviewer Expertise:

Prisons research, Quantitative methodologies, Personality disorder, Evaluation.

I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard.

References

This Research Note presents an update of a systematic review of worldwide recidivism rates published 3-years ago (Fazel & Wolf, 2015). Although the manuscript does not significantly add to the literature, as a research note it provides up-to-date results. In 2015, the authors concluded that recidivism data was not valid for international comparisons. This update draws the same conclusions. Overall, this systematic review is methodologically sound and highlights the inherent difficulties in adopting a comparative approach to recidivism. However, the manuscript would benefit from clarifying the results section as well as expanding the rationale.

Introduction:

1. It would be helpful to expand on the rationale for the review. In the introduction, the authors argue that “recently released prisoners often constitute a high-risk group that commit the majority of violent crimes” and then emphasize the public health burden of violent crime. However, much of the literature shows that recidivism events among recently released prisoners commonly involve justice administration offences (e.g., failure to comply with conditions of release). This may weaken the ‘public health burden’ argument and should be the subject of discussion in the manuscript.

Methods:

1. A justification for the selection of the bibliographic database (MEDLINE) should be provided, given that MEDLINE is generally used for biomedical research.

2. The abstract states that “three bibliographic indexes” were used, but this is not mentioned nor expanded upon in the text.

3. “If no new data had been identified for a particular country, we reported the rates from the original review”: in what percentage of cases did this occur? How many new or updated estimates were included?

4. It is unclear from the author list who “PS” is.

5. As per the PRISMA guidelines, it would be helpful to describe the method of data extraction (e.g., independently, in duplicate).  

6. According to the reference list, several reports were available in foreign languages only. How were they translated?

Results:

1. We agree with Reviewer 1 that results are difficult to follow along and that an effort should be made to match up the text with the figures and tables.

2. The rationale for Table 3 is unclear, given that it repeats information that is also provided in Table 2. Perhaps editing Table 2 or synthesizing the 2-year reconviction rates in the text would be more appropriate.

3. Table 4 often mentions that there was a change in reporting practices, which often results in considerable changes in rates (e.g., Denmark: 29% (2005), 63% (2013)). More details should be provided regarding the nature of the change in reporting practices.

4. It would be helpful to clarify if each study examines a population or a sample (for example, in the Notes section of Table 1).

5. If a study examines a sample rather than a population, it would be helpful to provide a confidence interval, if available.

Discussion:

• Given that it is not the objective of the current manuscript, it may be premature to extrapolate on the reasons for a change in rates in the Republic of Ireland.

Is the work clearly and accurately presented and does it cite the current literature?

Yes

If applicable, is the statistical analysis and its interpretation appropriate?

Yes

Are all the source data underlying the results available to ensure full reproducibility?

Yes

Is the study design appropriate and is the work technically sound?

Yes

Are the conclusions drawn adequately supported by the results?

Yes

Are sufficient details of methods and analysis provided to allow replication by others?

Yes

Reviewer Expertise:

Forensic mental health, violence, criminality, psychology

We confirm that we have read this submission and believe that we have an appropriate level of expertise to confirm that it is of an acceptable scientific standard, however we have significant reservations, as outlined above.

This Research Note updates a 2015 systematic review (same senior author) of criminal recidivism rates across countries, including rates of reconviction, re-arrest, and reimprisonment. This is an interesting and important area. The review was carefully conducted, although the findings are modest. As in 2015, the authors conclude that a meta-analysis was not possible. Because recidivism rates are not reported in a comparable fashion across enough countries, they were unable to make many meaningful comparisons or draw conclusions about the association between criminal justice practices and criminal recidivism. The authors provided a summary of the range of recidivism rates for studies reporting 2 year follow-up period (unadjusted). A key message underscores the importance of comparable reporting across countries, and the authors advocate the use of a report checklist to accomplish this. 

It would be very helpful if the authors made it easier to match up the text with the figures and tables. It was quite difficult to follow along, especially in the following areas:

1. The authors state: “We were able to examine recidivism over different time periods for 11 countries”. The results section of the manuscript never refers to these 11 countries. Table 3 refers to 11 countries if one thinks to remove those with asterisks (those included in the original review) but this table only refers to two-year reconviction rates – not the more generally stated recidivism rates. Table 4 identifies a different 11 studies, but this table compares reconviction rates for studies that had updated data from the 2015 review, and these findings are barely referenced in the results section. In sum, it would be helpful to identify the 11 countries and how they were selected.

2. In the first line of the results section, the authors stated that they identified 27 publications (also reported in Figure 1) that reported recidivism rates for 23 countries; they refer the reader to Tables 1 and 2. However, Tables 1 and 2 list 29 “studies” (Table 1) or “Sources” (Table 2) by my count, for 23 countries.

3. The following sentence is highlighted in both the abstract and manuscript: “Of the 50 countries with the largest prison populations, 10 reported recidivism rates for prisoners.” However, none of the figures or tables clearly depicts the list of 10 countries. Perhaps the authors could clarify the significance of the statement and identify the countries?

4. When reporting the key findings perhaps the authors could provide more help, such as:  “As shown in Table (?), the 2-year re-arrest rates ranged from 26% (list country) to 60% (list country), two-year reconviction rates ranged from 20% (list country) to 63% (list country), and two-year reimprisonment rates ranged from 14% (list country) to 43% (list country).

5. Small item: The authors state that “DY and PS” conducted the search. It is unclear who PS is in the list of authors.

6. Small item: In Table 1: Austria ( Statistik Austria, 2018): “ Reconviction: The conviction should happen during a follow-up period. ”The use of “should” is confusing.

Is the work clearly and accurately presented and does it cite the current literature?

Partly

If applicable, is the statistical analysis and its interpretation appropriate?

Not applicable

Are all the source data underlying the results available to ensure full reproducibility?

No source data required

Is the study design appropriate and is the work technically sound?

Yes

Are the conclusions drawn adequately supported by the results?

Yes

Are sufficient details of methods and analysis provided to allow replication by others?

Yes

Reviewer Expertise:

1. Interface between criminal justice and mental health systems.  Needs and outcomes of offenders.

We confirm that we have read this submission and believe that we have an appropriate level of expertise to confirm that it is of an acceptable scientific standard, however we have significant reservations, as outlined above.