On 2017 Feb 24, Mary Klem commented:

A primary rationale provided by Cooper et al. for conducting this study is that a previous review (Olatunji et al. 2014) used a search strategy that "was not systematic or clearly defined" (pg 111). Cooper et al. claim that they conducted a systematic search "...following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidance...(pg 110). However, details provided in the Methods section strongly suggest that Cooper et al. themselves failed to conduct searches that were systematic and that they have failed to provide a clear explanation of what and how they searched. Thus, this review suffers from the same flaws Cooper et al. identified in Olatunji et al 2014.

PRISMA recommends that authors provide, for each database searched, the database name, the platform used to search the database, and the start and end dates for the search of each database. Cooper et al., fail to do this, providing only database names and no start-end dates. They also include EBSCO in the list of databases searched, even though EBSCO is not a database. EBSCO is a platform that can be used to search a variety of databases, and it is not clear from the paper which databases were searched using this platform.

PRISMA also recommends that authors present the complete search strategy used for at least one of the major databases searched. Cooper et al. fail to do this, providing only what appears to be a simple description of their search terms. The authors note that the search terms "were searched in key words, title, abstract, and as MeSH subject headings" (pg 112). This is an odd statement, because the authors say they searched multiple databases, yet MeSH are controlled vocabulary only available for use in PubMed. So did the authors utilize each database's controlled vocabulary e.g., Emtree terms for Embase, PsycINFO thesarus terms? Or did they somehow attempt to use MeSH in these other databases and fail to use the appropriate controlled vocabulary? Given this apparent confusion about the nature of subject headings, I have little confidence that the authors conducted systematic or comprehensive searches.

Overall, then, this review suffers from a lack of clarity about the search strategies used, and the search strategies themselves are suspect. With these limits, it is unlikely that the findings of this study can add to the current literature in any substantive way.

On 2017 Feb 24, Mary Klem commented:

A primary rationale provided by Cooper et al. for conducting this study is that a previous review (Olatunji et al. 2014) used a search strategy that "was not systematic or clearly defined" (pg 111). Cooper et al. claim that they conducted a systematic search "...following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidance...(pg 110). However, details provided in the Methods section strongly suggest that Cooper et al. themselves failed to conduct searches that were systematic and that they have failed to provide a clear explanation of what and how they searched. Thus, this review suffers from the same flaws Cooper et al. identified in Olatunji et al 2014.

PRISMA recommends that authors provide, for each database searched, the database name, the platform used to search the database, and the start and end dates for the search of each database. Cooper et al., fail to do this, providing only database names and no start-end dates. They also include EBSCO in the list of databases searched, even though EBSCO is not a database. EBSCO is a platform that can be used to search a variety of databases, and it is not clear from the paper which databases were searched using this platform.

PRISMA also recommends that authors present the complete search strategy used for at least one of the major databases searched. Cooper et al. fail to do this, providing only what appears to be a simple description of their search terms. The authors note that the search terms "were searched in key words, title, abstract, and as MeSH subject headings" (pg 112). This is an odd statement, because the authors say they searched multiple databases, yet MeSH are controlled vocabulary only available for use in PubMed. So did the authors utilize each database's controlled vocabulary e.g., Emtree terms for Embase, PsycINFO thesarus terms? Or did they somehow attempt to use MeSH in these other databases and fail to use the appropriate controlled vocabulary? Given this apparent confusion about the nature of subject headings, I have little confidence that the authors conducted systematic or comprehensive searches.

Overall, then, this review suffers from a lack of clarity about the search strategies used, and the search strategies themselves are suspect. With these limits, it is unlikely that the findings of this study can add to the current literature in any substantive way.