This systematic review and meta-analysis have been registered at the international prospective register of systematic review and meta-analysis (PROSPERO). This review protocol adheres to the Preferred Reporting Items for Systematic Reviews and Meta-analysis Protocols (PRISMA-P, 2015) [20,21] (Additional file 1). PRISMA flow diagram will be presented to describe the screening and selection processes. The findings of the review will be illustrated through figures and tables.
Data sources and search strategies
A systematic search of databases like MEDLINE, PubMed, CINAHL, Science Direct index, and Google Scholar will be conducted without any time restriction and in accordance with a detailed search strategy. Both Medical Subject Headings (MeSH) and free text words will be used while searching for relevant articles. We will use the following search terms; “work-related musculoskeletal disorders” [-MeSH], “musculoskeletal pain” [-MeSH], “musculoskeletal disorders” [-MeSH], neck pain, spinal pain, back pain, low back pain, shoulder pain, elbow pain, groin pain, knee pain, ankle pain in combination with “workers”, “employees” “staffs”, adults, “occupation”, “workplace” “prevalence” and “Ethiopian”, “AND” and “OR” Boolean operator terms will be used as appropriate. The search query and details like time, date of search, terms used, and the number of hits/results will be recorded for every session to keep a note new studies add during the review period. The details of electronic search terms and strategies are included in the supplementary information (Additional file 2). Furthermore, we will also search grey literature resources such as a database or website of dissertations and theses, google, WHO websites and websites of other professional bodies(eg; Centers for Disease Control and Prevention, Workplace Health Promotion). The reference lists of the included articles will be hand-searched for additional eligible studies. Moreover, the corresponding authors will be contacted by mail whenever a need arise or for any difficulties faced during data extraction.
Inclusion and exclusion criteria
All observational studies reporting on the prevalence of musculoskeletal disorders and/or musculoskeletal pain with factors associated with musculoskeletal disorders among the adult working population of Ethiopia will be included. Article that meets the following criteria will be included: (1) Conducted solely among adult men or women Ethiopian those who work in governmental sectors or private sectors or self-employed, (2) reported the prevalence using standardized pain scales or questionnaires (eg: Standardized Nordic Questionnaire, Dutch Musculoskeletal questionnaire, or Visual Analogue Scale) providing sufficient information to calculate prevalence, and (3) Published in English language. Review, clinical commentary, conference abstracts, letter to editors, non-human articles and studies conducted outside of Ethiopia will be excluded. Studies published in non-English language will be excluded as we do not possess resources to pay or delegate volunteers to translate the data.
Study screening and selection for inclusion in the review
The titles and abstracts of articles retrieved from the search of different databases will be stored and managed in a Zotero version 5 reference manager. Two reviewers (BJ and KN) will independently review the titles and abstract part of all the articles and case of conflict or disagreement will be solved by discussion.
Data extraction and management
Once eligible studies are identified, two independent reviewers (BJ and KN) will extract the data using a prepared standardized data extraction form. Data such as first author’s last name, year of publication, study location within Ethiopia, sample size, response rate, reason for non-response, number of events, regions of pain reported,data on prevalence, recall period, ascertainment of outcome measures, risk factor or protective factors determined by each study along with their respective odds ratio (OR) and 95% confidence interval, and information needed for the risk of bias assessment will be extracted.
Risk of bias and quality assessment
Two review authors (BJ and KN) will independently assess the quality of all included studies using the Newcastle-Ottawa Quality Assessment tool adapted for cross-sectional studies [22,23]. The tool will be further adapted for use in this review (Additional file 3). Discrepancies of aggregate or total scores will be resolved by the third reviewer (TG) after a detailed evaluation of the source of the discrepancy. The tool contains three domains; selection of participants (3 items), quality of data (4 items), and definition of work-related musculoskeletal disorders (3 items). For the purpose of this review, all the items in the appraisal tool will be equally weighted and so the total score will be 10. There will be no subminimum score criteria for inclusion of studies.
Data synthesis
The prevalence rate, logarithm of prevalence, and standard error (SE) of the logarithm of prevalence will be computed. Correspondingly, for the factors associated, the logarithm of OR and SE of the logarithms of OR will be calculated. The pooled prevalence (proportion) of musculoskeletal disorders or musculoskeletal pain-related work and the pooled odds ratios (OR) of associated factors with a 95% confidence interval will be calculated using random-effects and quality effects models. The quality-effects meta-analysis [24] will be used to examine how the quality of each study influenced the pooled estimate compared with the results from the random effects [25]. The quality scores of each included study will be incorporated in the calculation of study weight to improve the robustness and help minimize the estimator variance and subjectivity in quality assessment. The presence of heterogeneity among studies will be examined using both Cochrane’s Q statistics and the I2 statistics. I2 values greater than 50% will be declared as the presence of substantial heterogeneity [26,27]. Funnel plots will be used to assess publication bias[28] and in addition Egger’s regression test (p<0.05) [29] and Beggs equations will be computed to declare publication bias. Double arsine transformation will be used in case of variance instability [30].
Possible subgroups will be identified based on the study characteristics and population characteristics. Subgroup analysis will be performed to determine the source of heterogeneity attributed to gender, sample size, place of study, study setting, year of publication, outcome tool used, type of occupation, and region of pain. Sensitivity analysis will be performed after excluding each study one by one and the pooled estimate will be calculated for the remaining studies. All statistical analyses will be performed using Meta XL version 5.3 [31] and STATA 15 Metaprop package [32].
Presenting and reporting of the results
The study selection step by step process will be outlined in a flow diagram and the reasons for exclusion will also be mentioned. The study characteristics, risk of bias, and quality assessment of the included studies will be presented in tables. Forest plots will be used to display the pooled estimates of prevalence proportions.