Occupational Related Shoulder and Neck Pain Among Working Population of Ethiopia: Systematic Review and Meta-Analysis

Background: Currently, work-related musculoskeletal disorders are a signicant public health concern and are one of the leading causes of disability-adjusted life years and reducing quality of life. Therefore, the current study aimed to provide the country-wide prevalence of work-related musculoskeletal disorders, particularly shoulder and neck pain, in Ethiopia. Methods: This study considered studies conducted in Ethiopia, written in English and published in 2017-2020 and searched using included electronic databases such as PubMed/MEDLINE, Web of Science, Google Scholar, CINAHL, SCOPUS, Embase, African Index Medicus, and African Journals Online database. The quality assessment of the studies was done using Joanna Briggs Institute Critical Assessment tools to determine the relevance of each included article to the study. Results: The study found that the pooled prevalence of shoulder and neck pain in the previous year represented 37.9% [95% CI:26.5, 50.8%] and 29.9% [95% CI: 20.1, 41.9], respectively. Based on the subgroup analysis, the pooled prevalence of shoulder pain in the last year based on the study population, publication year and study region was 47.6% [95% CI: 45.8, 49.4%], 49.8% [95% CI: 45.7, 53.9%] and 44.6% [95% CI: 41.4, 47.8%], respectively, while the pooled prevalence of neck pain in the last year based on the study population, publication year and study area was 39.1% (95% CI: 37.5, 40.7%], 25.1% [ 95% CI: 20.8, 29.9%] and 32.6% [95% CI: 29.8, 35.5%], respectively. Conclusions This study found that at least one third of the study participants had experienced occupational-related shoulder and/or neck pain the previous year. The study suggests that there is a need to implement occupational health and safety to reduce work-related musculoskeletal disorders and other hazards.


Introduction
Musculoskeletal disorders (MSD) are a major public health problem that affect various regions of the body, such as shoulder, elbow, lower back, hips, knees, wrist, neck, hands, upper back, ankle, and feet [1][2][3] and are characterized by symptoms such as pain, ache, and discomfort [4,5]. Workers working in different working environments such as health care, driving, manufacturing industry, general labor, maintenance, repair, and cleaning are potentially at risk of musculoskeletal disorders [6].
According to the Global Burden of Disease report in 2016, MSDs were among the leading causes of disability-adjusted life years [7] with a double burden of economic costs, healthcare service utilization and social problems [8,9]. Occupational-related health problems such as shoulder and neck pain are among the most common causes of morbidity and absenteeism from work and reduced productivity in many countries [10][11][12][13] and have multifactorial biopsychological origin and socioeconomic costs [9,13,[14][15][16].
Two thirds of all populations experience neck pain at some point in their lives [17]. From 1990 to 2010, the effect of adjusted life years for neck pain increased from 23.9 million to 33.6 million [18]. According to the Global Burden of Diseases reported in 2015, neck pain was among the leading causes of disability in most parts of the country [19].
In developing countries, the implementation of occupational health and safety practices is often neglected and preventive measures are poor [20]. As a result of lack of adequate training, poor awareness, and under-reporting of problems, MSD related to work have increased in developing countries [21] and remain less prioritized [22]. In Ethiopia, several studies are conducted on work-related MSDs such as neck and shoulder in various occupational settings [23][24][25][26][27][28][29][30][31][32][33].
as neck and shoulder MSDs that can be crucial for policy makers or / and the ministry of health in designing prevention and control programs and for a better understanding of the current evidence on the prevalence of shoulder and neck pain. Therefore, this study aimed to determine the pooled prevalence of work-related shoulder and neck musculoskeletal disorders related to work in Ethiopia.

Methods
This study aimed to determine the overall prevalence of shoulder and neck musculoskeletal disorders in the previous year. The study was carried out according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines [34].
Eligibility criteria.
Articles that met the following predetermined inclusion criteria were included in the systematic review and metaanalysis.
i. Population: Working population of Ethiopia regardless of their occupation.
ii. Outcome: Articles on the prevalence of MSD and reported a one-year prevalence of shoulder and/or neck pain.
iii. Study design: A cross-sectional study that provides quantitative results (magnitude, frequency, or prevalence or rate). Data/Information Sources and Search Strategies.
The searches of the literature were performed using keywords from systematic review and meta-analysis using search strategies such as the databases SCOPUS, PubMed/ MEDLINE, Embase, Cochrane Library, African Index Medicus, Google Scholar, CINAHL and African Journals online. Articles were searched using a combination of Boolean logic operators ("AND, OR and NOT"), medical subject headings (MeSH) and keywords.
The following are among the search terms that the authors use (DA. Mengistu, and YM. Demmu) used in the initial search of literature from included databases: "Prevalence "OR "Magnitude" AND "Occupational" OR, 'Occupational related' OR 'Work related' OR 'Ergonomic related' AND 'Musculoskeletal' OR 'shoulder' OR 'Neck' AND 'Disorders' OR 'Disease' OR Problems' OR "Pain' OR "Injury" AND 'Working group' OR 'Working population' OR 'Workers' AND 'Ethiopia.
Furthermore, manual searching of the literature was made to cover those articles di cult to locate and missed from the included electronic databases. Finally, all identi ed keywords and index terms were checked across the electronic databases. The last search was done on 22 August 2020.

Outcomes Measure
The primary outcome of interest was the prevalence of occupational-related shoulder and neck disorders/pain that was estimated or reported by dividing those experienced disorders by the total population at a given time. Furthermore, the prevalence of shoulder and neck pain was estimated by dividing the number of people who experienced shoulder or neck pain by the sample size of each study for articles that did not report the prevalence or rate.
Study selection.
Duplicated articles were removed using the ENDNOTE software version X5 (Thomson Reuters, USA). The author (DA. Mengistu, and YM. Demmu) screened the titles and abstracts of the identi ed articles by applying the inclusion and exclusion criteria.
The study selection process was performed using the PRISMA ow chart showing the articles included in the study and the articles excluded from the study for the reasons. Finally, the systematic review and meta-analysis included studies conducted in Ethiopia and published from 2017 to 2020 that reported the last year prevalence of shoulder and neck musculoskeletal disorders.

Data Extraction and Quality Assessment
The author extracted the required data from the eligible articles. Relevant data required for the study were extracted under the following headings: author/s; year of publication; sample size, study region; study design and primary results were extracted using a Microsoft Excel, 2016 format.
The selected articles were subjected to a rigorous evaluation using standardized critical evaluation tools, Joanna Briggs Institute (JBI) Critical Evaluation Tools) [35] to determine the quality and relevance of each article by the authors independently. Then the score was taken across the articles and classi ed as high (85% and above score), moderate (60-85% score) and low (<60% score) quality. The included articles were subjected to the evaluation (appraisal) by the authors (DA. Mengistu, and YM. Demmu) independently and to check the accuracy of the work and reduce the error.
Data Analysis and Statistical Procedures.
The pooled prevalence of MSD related to shoulder and neck pain in the previous year was done using Comprehensive Meta-Analysis (CMA) version 3.0 statistical software. Furthermore, the forest plot and the random-effects model were used to determine the pooled prevalence of shoulder and neck pain in the previous year.
The publication bias of the included studies was evaluated using funnel plots and the P-value of < 0.05 was considered evidence of publication bias. Furthermore, the subgroup analysis was performed based on the year of publication, study population/occupation categories, and study region to minimize random variations between the included studies.
Finally, the results were presented using texts, tables, and graphs/ gures.

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 prevalence estimates due to genuine variation in prevalence [36,37]. Additionally, subgroup analysis was performed based on the years of publication, occupation and study areas to determine the heterogeneity in the prevalence of shoulder and neck pain.

Results
Study Selection. were assessed for eligibility. Finally, a total of 11 articles were included in the systematic review and meta-analysis ( Figure 1).
Based on the JBI Critical Appraisal tool [35], all included articles had a low risk of bias. The prevalence of shoulder and neck pain related to work in the previous year ranged from 10 Table 1).

Prevalence of Musculoskeletal Disorders
The meta-analysis was performed using the Comprehensive Meta-Analysis (CMA) Version 3 statistical package (software) to determine the combined prevalence of shoulder and neck musculoskeletal disorders in Ethiopia.

Prevalence of occupational-related shoulder pain
Overall pooled prevalence of shoulder pain.
The pooled prevalence of occupational-related shoulder pain in the previous year was found to be 37.9% with a 95% CI of 26.5 to 50.8%; I 2 = 98.51% with a P-value < 0.001 ( Figure 2).
Subgroup analysis of the pooled prevalence of shoulder pain.
Based on the subgroup analysis of the pooled prevalence of shoulder pain related to work based on the study population or participants, the overall pooled prevalence of shoulder pain in the previous year was 47.6% (95% CI: 45.8, 49.4% with a P value of =0.009]. Furthermore, after the subgroup analysis was performed based on the year of publication, the total pooled prevalence of occupational-related shoulder pain in the previous year was 49.8 % with 95% CI 45.7, 53.9%) and a P value of >0.05]. After the subgroup analysis of the prevalence of shoulder pain was performed by study region, the overall pooled prevalence of occupational-related shoulder pain was 44.6 % with 95% (supplementary material I).
Prevalence of occupational-related neck pain.
Overall prevalence of neck pain.
The pooled prevalence of occupational-related neck pain in the previous year was 29.9% with a 95% CI of 20.1, 41.9% with a p-value of 0.002 and I 2 = 98.29% with P-value < 0.001 (Figure 3).
Subgroup analysis of the prevalence of occupational-related neck pain.
After the subgroup analysis of work-related neck pain in the previous year based on the study population, the overall pooled prevalence of occupational-related neck pain in the previous year was 39.1% (95% CI 37.

Discussion
This study was aimed to determine the pooled prevalence of occupational-related shoulder and neck pain in the previous year in Ethiopia based on previously published articles. In the current study, a total of 4713 study participants were included in 11 articles published in Ethiopia [23][24][25][26][27][28][29][30][31][32][33].
Musculoskeletal disorders such as neck and shoulder pain are the leading causes of loss of productivity, employee absenteeism, and affect quality of life. The current study found the pooled prevalence of occupational-related shoulder pain in the previous one-year account 37.9% [95% CI:26.5, 50.8%; P-value < 0.001]. However, the pooled prevalence of shoulder pain increased to 47.6%, 49.8% and 44.6% after the subgroup analysis of the prevalence based on the study population, publication year, and study region, respectively.
In general, the current study found that at least two of the seven study participants experienced occupational-related shoulder pain, while three of the eight study participants experienced occupational-related neck pain regardless of the occupation categories. This indicates that occupational-related MSDs continue to have potential health and economic impacts. Thus, the implementation of occupational health and safety practices such as engineering control, administrative control, and the use of personal protective devices in the workplace plays an important role in reducing these problems [38,39].

Limitations
There was an unequal distribution of occupations among the included articles. On the other hand, the prevalence of MSDs such as shoulder and neck pain in some regions of Ethiopia was not covered due to the lack of studies in those regions. Furthermore, cross-sectional studies were included, and causal relationships between MSDs and risk factors cannot be established.

Conclusions
Occupational-related musculoskeletal disorders continue to have a potential impact on worker health, productivity, and Availability of data and materials.
Almost all data are included in this study. However, additional data will be available from the corresponding author upon reasonable request.

Competing Interests
The author declares that there is no competing interest in this work.

Funding
Not applicable.

Authors' Contributions
DAM conceived the idea and played an important role in data review, extraction and analysis, writing, drafting, and editing the manuscript. DAM, and YMD have contributed to data extraction and analysis. Finally, the authors (DAM, and YMD) read and approved the nal version of the manuscript to be published and agreed on all aspects of this work. Table 1 Overall characteristics of included articles in the systematic review and meta-analysis, 2020.  Figure 8 Forest plot shows the subgroup analysis of pooled prevalence of occupational related neck pain in the previous one year based on publication year, 2020.

Figure 9
Forest plot shows the subgroup analysis of pooled prevalence of occupational related neck pain in the previous one year based on study region,2020.