Strengthening literature search strategies for systematic reviews reporting population health in the Middle East and North Africa: A meta‐research study

Abstract Objective In the Middle East and North Africa (MENA), data are produced in languages other than English and available through gray literature sources. We assessed the comprehensiveness of literature search strategies of systematic reviews (SRs) reporting population health primary data on MENA. Methods Utilizing the registered protocol (PROSPERO CRD42017076736), we conducted a meta‐research analysis on a cohort of SRs (systematic PubMed search: from 2008 to 2016) and evaluated their search strategies following AMSTAR recommendations. Results A total of 379 SRs were included. Few SRs (10.3%, n = 39) conducted a comprehensive literature search including at least two databases, reference lists of included primary studies, gray literature sources, and no language restriction. Nevertheless, 90.5% (n = 343) searched at least two databases and 67.0% (n = 254) searched gray literature sources. Authors from MENA searched statistically more for gray literature than authors from Western countries (P = 0.022). Reference lists of the included studies were searched in 40.4% (n = 153) of the SRs. Searching the reference lists was positively associated with searching for gray literature (P < 0.001). Only 38.8% (n = 147) of the SRs had no language restriction or searched in English and in at least one language relevant to MENA, whereas 27.2% (n = 103) did not report this information. Conclusions Literature searches for SRs reporting population health data on MENA were limited in reporting quality, language restrictions, and lack of reference list searches. This was probably due to lack of adherence to the reporting guidelines. To ensure compilation of optimum evidence, expanding literature searches to reference list search and for additional languages relevant to MENA are required.

in non-indexed journals affiliated to local universities. This is a potential challenge for a comprehensive literature search, since the information may not be easy to search and/or to retrieve.
Our meta-research study is part of the Population Health Publications Assessment Project aiming to assess the methodological quality and the use of gray literature in published SRs on population health in MENA. 10,11 This study aimed to evaluate the comprehensiveness of the literature search strategies utilized in SRs reporting population health data in MENA and to explore the variability of the search strategies, and to provide recommendations to strengthen literature search strategies for SRs.

Study design
Based on a published protocol 9 (PROSPERO registration number CRD42017076736), 12 we conducted a meta-research analysis of the comprehensiveness of the systematic reviews' literature search. First, we conducted a systematic overview to systematically identify a cohort of SRs. The study is reported following PRISMA statements.

Eligibility criteria and selection
We included all SRs reporting population health data on countries in the MENA region, published and indexed on PubMed(13) between 2008 and 2016. The 20 countries included in our review were Algeria, Bahrain, Djibouti, Egypt, Iraq, Jordan, Kuwait, Lebanon, Libya, Morocco, Oman, Pakistan, Palestine, Qatar, Saudi Arabia, Sudan, Syria, Tunisia, United Arab Emirates, and Yemen. The selection process of these 20 MENA countries was described in our protocol. 9 We included SRs of observational studies presenting descriptive epidemiological data and excluded clinical and interventional study SRs. Narrative reviews or synthesis papers analyzing primary studies, which did not follow a systematic process were excluded. Based on PRISMA-P terminology, 14 we defined a SR as a review of primary studies reporting a search strategy for at least one electronic database along with eligibility criteria, which were applied during a multistage process of study selection. Population health was defined as the health outcomes of a group of individuals including the distribution of such outcomes within the group. 15 The literature search strategy published in our protocol 9

Data extraction
Systematic review characteristics (gray literature search, reference list checking, database search, language restriction, year of publication, geographical coverage, and health topic) and authors' country of affiliations and potential collaborations were extracted by one author and checked for accuracy by a second author. Discrepancy meetings including all the authors were set up after each stage of the screening process and following data extraction checks. We retrieved the journals' impact factor (JIF) during the year of publication from the Institute of Scientific Information's Journal Citation Report. 19 The list of included SRs along with their characteristics are presented in Supplementary Material S2.

Data analysis
We assessed the comprehensiveness of the literature search strategy used in the included SRs by focusing on four criteria: searches of at least two databases and reference list, search for gray literature, and use of languages during the literature search, as recommended by AMSTAR guidelines. 6 We also evaluated the proportion of SRs report-

RESULTS
The initial literature search identified 5 747 articles. Thereafter, double multi-stage screening included a cohort of 379 SRs ( Figure 1).

DISCUSSION
In this meta-research study, we identify that a minority of SRs reporting population health data on MENA countries utilized a and 39% reported no language restriction. 28 In contrast, our study findings suggest that SRs' authors were reporting data on MENA search more frequently for gray literature (67%) to identify research not disseminated in journals controlled by commercial publishers. We observed that all SRs, however, did not extend their search to include languages relevant to MENA. Consequently, these published SRs may be missing essential data pertinent to the region.
We make the point that authors' adherence to reporting and methodological guidelines such as PRISMA and AMSTAR will improve the quality of the SRs reporting data on MENA. Emphasis must be made on the importance of a comprehensive literature search, particularly for this region since research is disseminated in languages other than English. We recommend that literature searches should be extended to Arabic, French, and/or Urdu, depending on the geographical coverage of the epidemiological SRs.
We believe this is the first study that evaluates the comprehensiveness of literature search strategies utilized in SRs reporting on population health data in MENA. We aimed to estimate the proportion of the included systematic reviews that comprehensively conducted their literature search, and to assess the differences between these systematic reviews according to their search. Consequently, we did not conduct an overview of systematic reviews in order to report a nar- Our assessment of the search strategy was based on the reporting quality of the SRs. Hence, we may have been conservative in our evaluation of the methodology of some SRs due to a lack of comprehensiveness in reporting. Furthermore, the assessment was conducted using the original version of the AMSTAR checklist. 6