Prevalence of Occupational Related Upper and Low Back Musculoskeletal Disorders in Ethiopia: Systematic Review and Meta-Analysis

Background: Occupational related musculoskeletal disorders (MSDs) are a major public health problem and result in the growing demands of healthcare service utilization, causing temporary and permanent disability and reduced quality of life. In developing countries, particularly in Ethiopia, there is no adequate evidence on the overall prevalence of occupational-related MSDs and remains less prioritized and empirically unrepresented. Thus, this study aimed to determine the pooled prevalence of occupational-related musculoskeletal disorders, particularly low and upper back musculoskeletal disorders in Ethiopia. Methods: This systematic review and meta-analysis considered studies conducted in Ethiopia, written in the English language, and published from 2017-2020. The articles were searched using the following electronic databases such as Web of Science, SCOPUS, PubMed, Google Scholar, CINAHL, Cochrane Library, African Index Medicus, African Journals Online database, and Science direct using a combination of Boolean logic operators, Medical Subject Headings, and main keywords. Quality assessment of the articles was done using the Joanna Briggs Institute Critical Appraisal tools to determine the relevance of articles to the study. Results: The current study found the pooled prevalence of occupational-related upper back pain and low back pain in the previous one year was 27.1% [95% of CI: 18.4, 37.9%] and 54.2% [95% of CI: 48.2, 60.0%] respectively. However, the pooled prevalence of occupational-related upper back pain in the previous one year after subgroup analysis based on publication year, study population, and study area was 43.8% [95% of CI: 39.3, 47.7%], 34.7%[95% of CI: 33.1, 36.2%] and 36.2% [95% of CI: 33.6, 39.0%] respectively while the pooled prevalence of occupational-related low back pain in previous one year based on subgroup analysis by publication year, study population, and study area was 61.8% [95% of CI: 58.9, 64.6%], 52.8% [95% of CI: 51.3, 54.3%] and 55.2% [95% of CI: 51.4, 59.0%]


Background
Musculoskeletal disorders (MSDs) are impairments of the body affecting various body parts such as muscles, tendons, ligaments, joints, nerves, bones, and blood circulation system [1,2] and characterized by various symptoms such as pain, ache, and discomfort [, 3,4]. Workers involved in various occupational settings such as health care, driving, manufacturing, general labor, maintenance or repairing, and cleaning are at the highest risk of MSDs [5].
Globally, occupational-related MSDs are among the most common leading causes of worker complaints [13]. According to the Global Burden of Disease report, 2016, musculoskeletal disorders were the leading cause of disability-adjusted life years [14] with a double burden of economic costs and healthcare needs as well as a major social problem [15]. Annually, more than 2.3 million people die from an occupational injury or related diseases [16,17]. In developing countries where there is poor awareness of ergonomics issues, lack of adequate training, and problems are underreported, occupationalrelated MSDs have been increased [18].
Furthermore, health and safety procedures are often disregarded, and infrastructure and preventive measures are poor in developing countries [19]. In developing countries, occupational-related MSDs remain less prioritized and empirically unrepresented [20] and only ve to ten percent of workers get access to basic occupational health services [21].
There are many studies conducted on occupational-related MSDs such as upper and low back pain in different occupational settings in Ethiopia [22,23,[29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48]. However, no study that provides adequate evidence on the overall pooled prevalence of upper and low back MSDs that can be important for policymakers, the federal Ministry of Health, and for a better understanding of the current evidence on the prevalence of upper and low back MSDs in Ethiopia. Thus, this study aimed to determine the pooled prevalence of occupational-related upper and low back musculoskeletal disorders among the working population in Ethiopia.

Methods
This study included articles that reported the prevalence of low back pain or/and upper back pain musculoskeletal disorders in the previous one year. This study was conducted under the Preferred Reporting Items for the Systematic Reviews and Meta-Analysis (PRISMA) guidelines [24].

Eligibility Criteria.
The articles that met predetermined inclusion criteria were included in the systematic review and meta-analysis. A crosssectional study design conducted in Ethiopia from 2017 to 2020 that provided quantitative outcomes (magnitude, frequency, or prevalence) of low and/or back musculoskeletal disorders in the last twelve months was included in this study. Furthermore, the study included full-text articles written in the English language and published in peer-reviewed journals from 2017 to 2020.

Information Sources and Search Strategy.
The searches were focused on keywords of the systematic review and meta-analysis through search strategies such as Web of Science, SCOPUS, PubMed, Google Scholar, CINAHL, Cochrane Library, African Index Medicus and African Journals Online databases and Science Direct. The articles were searched using a combination of Boolean logic operators (AND, OR, and NOT), Medical Subject Headings (MeSH), and major keywords.
The following is a search term, the authors (DA. Mengistu and YM. Demmu) used in the initial searching of articles: "Prevalence "OR "Magnitude" AND "Occupational-related" OR "Work-related" AND "Musculoskeletal" OR "Low back" OR "Upper back" AND "Disorders" OR "Disease" OR " Problems" OR "Pain" OR "Injury" AND "Working group" OR "Working population" OR "Workers" AND "Ethiopia". Furthermore, the manual searching was made to cover the search missed from the electronic databases.
Finally, all identi ed keywords and an index term were checked by the authors (DA. Mengistu and YM. Demmu) across the included electronic databases. The last search was done on 12 October 2020.

Study Selection
After searching, duplicated articles were removed using the ENDNOTE software version X5 (Thomson Reuters, USA). The authors (DA. Mengistu and YM. Demmu) screened the titles and abstracts of the identi ed articles by applying the predetermined inclusion and exclusion criteria. Finally, the systematic review included articles conducted in Ethiopia and published from 2017 to 2020 that reported the last one-year prevalence of occupational-related musculoskeletal disorders (low and upper back pain) in different occupational settings.

Data Extraction and Quality Assessment
The authors (DA. Mengistu and YM. Demmu) independently extracted the required data from the eligible articles. The relevant data required for the study under the following headings: author; publication year; sample sizes, study area/region; study design, and primary outcomes of interest were extracted using a Microsoft Excel, 2016 format.
The quality of each article was assessed to evaluate and to con rm the relevance of the articles to the study. The selected articles were subjected to a rigorous and independent appraisal using standardized critical appraisal tools, Joanna Briggs Institute (JBI) Critical Appraisal tools) [25] to determine the quality and relevance of the articles. Then the score was taken across all studies and graded as high (85% and above score), moderate (60-85% score), and low (< 60% score) quality. Disagreements made between authors (DA. Mengistu and YM. Demmu) were solved by discussion after repeating the same procedure.

Data Analysis and Statistical Procedures.
The pooled prevalence of occupational-related low and upper back musculoskeletal disorders in the previous one year was done using Comprehensive Meta-Analysis (CMA) version 3.0 statistical software. The forest plot and random-effects model were used to determine the pooled prevalence of selected musculoskeletal disorders in the previous year.
The publication bias of included articles was evaluated using funnel plots and a P-value of less than 0.05 was considered as the evidence for publication bias. Furthermore, the subgroup analysis based on the publication year, occupation categories/population, and the study region was done to minimize the random variations between the point estimates of the included articles. Finally, the characteristics of the included articles were presented using texts, tables, and graphs.

Heterogeneity
Cochran's Q test (Q) and I Squared test (I 2 statistics) were used to evaluate the heterogeneity among the included articles. I 2 statistics is the proportion of the variation in the estimates of prevalence due to genuine variation in prevalence [26,27]. The level of heterogeneity was divided into four categories; no heterogeneity (0%), low (25-50%), moderate (50-75%), and high (greater than 75%). [28]. Furthermore, subgroup analysis and meta-regression were used to determine the heterogeneity in the prevalence of MSDs based on the years of publication, occupation/study population, and study areas.

Study Selection
About 1114 articles, editorials, and reports were searched through electronic databases such as Web of Science, SCOPUS, PubMed, Google Scholar, CINAHL, Cochrane Library, African Index Medicus, African Journals Online databases and Science direct from 10 September to 12 October 2020. Following the searching of articles, 285 duplicated articles were excluded. Furthermore, 706 articles were excluded after initial screening, and 35 articles excluded after full-text articles were assessed for eligibility, of which 20 articles were included in the systematic review and meta-analysis (Fig. 1).

Prevalence of Musculoskeletal Disorders
The meta-analysis was conducted using the Comprehensive Meta-Analysis (CMA) Version 3 statistical package (software) to determine the pooled prevalence of occupational-related low back and upper back musculoskeletal disorders in Ethiopia.

Overall Pooled Prevalence of Upper Back Pain
The pooled prevalence of occupational-related upper back pain in the previous one year was 27.1% with 95% CI of 18.4 to 37.9%; I 2 = 98.029% with p-value < 0.001 (Fig. 2).

Subgroup Analysis of Prevalence of Upper Back Pain by Study Population
Based on the subgroup analysis of prevalence by the study population, the lowest prevalence [ Furthermore, after the subgroup analysis was done based on the study region, the overall pooled prevalence of occupational-related upper back pain was 36.2 % with 95% CI: 33.6, 39.0%) and a p-value of < 0.001] (Fig. 5).

Overall Prevalence of Low Back Pain
The pooled prevalence of occupational-related low back pain in the previous one year was 54.2% with 95% CI of 48.2, 60.0 with p-value of 0.173 and I 2 = 96.78% with a P-value < 0.001 (Fig. 6).

Prevalence of Low Back Pain Based on Study Population
Based on the subgroup analysis of prevalence by the study population, the lowest prevalence [25.5% (95% CI: 21.5, 29.9%) with a p-value < 0.001] of occupational-related low back pain in the previous one year was reported among construction workers whereas the highest prevalence [67.3% (95% CI: 62.7, 71.6%) with a p-value of < 0.001] was reported among pedestrian back-loading women.
Furthermore, after subgroup analysis was done based on study population or participants, the overall pooled prevalence of occupational-related low back pain in the previous one year was 52.8% (95% CI: 51.3, 54.3% with a P-value of < 0.001] (Fig. 7). Furthermore, after the subgroup analysis was done based on the year of publication, the overall pooled prevalence of occupational-related low back pain in the previous one year was 61.8 % with 95% CI: 58.9, 64.6%) and a p-value < 0.001] (Fig. 8).

Prevalence of Low Back Pain by Study Areas (Region)
Based on the subgroup analysis of the pooled prevalence of occupational-related low back pain by study region, the lowest pooled prevalence [50.7% (95% CI: 25.0, 76.0%)] was reported among the studies conducted in Tigray regional state whereas the highest prevalence [56.3%, (95% CI: 37.1, 73.9%)] was reported among the studies conducted in Southern Nations, Nationalities, and Peoples.
Furthermore, after the subgroup analysis of the prevalence of low back pain was done by the study region, the overall pooled prevalence of occupational-related low back pain was 55.2 % with 95% CI: 51.4, 59.0%) and a p-value of a = 0.007] (Fig. 9).

Discussion
The current study was conducted to determine the pooled prevalence of occupational-related musculoskeletal disorders; lower back and upper back pain in the previous one year in Ethiopia based on previously (2017-2020) published articles.
Musculoskeletal disorders are the leading causes of loss of productivity and employee absenteeism and affect the quality of life [49,50]. The study found the prevalence of low back pain among various groups of the working population of Ethiopia ranged from 25.5-67.3% that was lower than the nding of another study conducted in Saudi Arabia and found the prevalence of lower back pain in different professional groups ranged from 64% and 89% [51].
Furthermore, the current found pooled prevalence of occupational-related low back pain accounted 54.2% [95% of CI: 48.2, 60.0%] that was relatively smaller than the pooled prevalence of low back pain in Africa accounted 57% [52]. The difference may be related to the scope of the study or variation in the implementation of occupational health safety practices or low awareness on occupation health issues. workers. The variation may be related to the variation in activities or workload or working time or nature of the work or availability and implementation of occupational health safety services.
In general, the current study found that at least one out of four study participants experienced work-related upper back musculoskeletal disorders, whereas one out of two participants experienced work-related low back pain regardless of the occupation categories. Thus, the implementation of occupational health and safety practices such as engineering control, administrative control, and the use of personal protectives in the working environment plays an important role in reducing these problems [53,54].

Limitations
There was an unequal distribution of the occupations among the included articles. On the other hand, the prevalence of MSDs in some regions of Ethiopia was not covered because of the lack of studies in those regions.

Conclusions
Occupational related musculoskeletal disorders continue to have a potential impact on worker's health, productivity, and quality of life worldwide. This systematic review and meta-analysis found that more than half of the included participants experienced low back pain at least once a time in the previous one year, whereas more than one-fourth of the included participants experienced upper back pain. Thus, applying occupational health and safety practices in the working environment plays an important role in reducing these problems. Almost all data are included in this study. However, additional data will be available from the corresponding author on reasonable request. PRISMA-P (Preferred Reporting Items for Systematic Review and Meta-Analysis) 2015 checklist is one of the recommended items to address in a systematic review and Meta-analysis.
The authors declare that they have no competing interests in this work.

Funding
This review did not receive any grants/funds Authors' Contributions DA. Mengistu conceived the idea and had major roles in the data review, extraction, and analysis, writing, drafting, and editing of the manuscript. YM. Demmu has contributed to data extraction, analysis, and editing. Finally, the authors (DA. Mengistu, YM. Demmu) read and approved the nal version of the manuscript to be published and agreed on all aspects of this work.