Duration of exposure and educational level as predictors of occupational respiratory symptoms among adults in Ethiopia: A systematic review and meta-analysis

Our plain-English summary of Duration of exposure and educational level as predictors of occupational respiratory symptoms among adults in Ethiopia: A systematic review and meta-analysis, by B. Dagnew, Z. Andualem, D.A. Angaw, et al (SAGE Open Medicine, 2021).

The study

• Authors: B. Dagnew, Z. Andualem, D.A. Angaw, K. Alemu Gelaye, H. Dagne
• Journal: SAGE Open Medicine
• Published: 2021;9:20503121211018121
• Type of article: Review
• Cited by: 10 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Introduction: Occupational respiratory symptoms are manifestations of respiratory diseases because of exposure to dust or chemicals such as asbestos, silicon and aluminium in the workplace like cement factory, tannery, textile and/or street sweeping, all of which affect the health condition and productivity. In Ethiopia, several primary studies were conducted regarding the magnitude of occupational respiratory symptoms with the prevalence of 68.89% in street sweepers and associated factors with inconsistent results. This meta-analysis aimed to pool the prevalence of respiratory symptoms and their associated factors among Ethiopian adults working in different workplaces.

Methods: PubMed, African Journals Online, Google Scholar, Cochrane Library and Direct Google were systematically searched to identify primary studies. Two authors performed data abstraction and quality assessment for each included study independently. Cochran's Q-statistic and I2 (I-squared) statistic were used to check heterogeneity. DerSimonian and Laird random-effects models were used to estimate the pooled prevalence and associated factors of respiratory symptoms. Publication bias was checked by funnel plot and Egger's test, and also sensitivity analyses were performed.

Results: Ten primary studies with 3441 study participants were included for the narrative synthesis and meta-analysis of the pooled prevalence of occupational respiratory symptoms. The pooled prevalence of overall occupational respiratory symptom was 54.58% (95% CI: 45.37-63.79). Dry cough was the most encountered respiratory symptom [34.93, 95% CI: 29.52-40.35], followed by breathlessness [28.67%, 95% CI: 20.13-37.22]. Work experience of over 5 years [OR = 2.24, 95% CI: 1.21-4.16] and educational level of Grade 8 and lower [OR = 1.28, 95% CI: 1.06-1.55] were significantly associated with occupational respiratory symptoms.

Conclusion: In this review, the pooled prevalence of occupational respiratory symptoms was high. The findings of this study dictate the need for the implementation of workplace safety measures. Special attention is required to employees with lower educational level and longer duration of work experience.

Prospero Registration: CRD42020176826.

© The Author(s) 2021.

In plain English

This systematic review and meta-analysis pooled ten cross-sectional studies of dust-exposed workers in Ethiopia, with 3441 participants aged 18 to 68. The studies covered street sweepers and cement, textile, tannery and flour mill workers. Asbestos appears only in the article's background, and the review did not examine asbestos exposure. Overall, 54.58% of workers reported respiratory symptoms (95% CI 45.37 to 63.79), with large differences between studies. Dry cough was the most common symptom (34.93%, 95% CI 29.52 to 40.35), followed by breathlessness (28.67%, 95% CI 20.13 to 37.22). Working more than 5 years, versus 5 years or less, was linked to higher odds of symptoms (pooled odds ratio 2.24, 95% CI 1.21 to 4.16). Grade 8 education or less, versus secondary or above, was also linked to higher odds (pooled odds ratio 1.28, 95% CI 1.06 to 1.55). Sex was not significantly associated with symptoms. The authors concluded that prevalence was high and that workers with lower education and longer work experience needed special attention. They cited high heterogeneity, few participants and no studies from most regions as limitations.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Systematic review and meta-analysis (random-effects) of observational studies. All ten included studies were cross-sectional.
• Who was studied: Ten primary studies with 3441 adult workers in Ethiopia (1983 male, 1458 female, aged 18 to 68). Seven were published from 2014 to 2019 and three were unpublished. They came from Addis Ababa, Oromia, Amhara and SNNP regions, and studies were searched up to 28 March 2020.
• Exposure: Workplace dust exposure in street sweeping, cement factories, a textile factory, a tannery and a flour mill. Duration of work (more than 5 years vs 5 years or less) was analysed as a factor. Asbestos is mentioned only in the introduction as one of several workplace chemicals and was not studied as a separate exposure.
• Main results:
  • Pooled prevalence of overall occupational respiratory symptoms across all ten studies was 54.58% (95% CI: 45.37 to 63.79), with significant heterogeneity between studies (I-squared 96.9%).
  • Dry cough was the most common symptom (34.93%, 95% CI 29.52 to 40.35), followed by breathlessness (28.67%, 95% CI 20.13 to 37.22). Pooled prevalence of phlegm was 27.88%, wheezing 22.14% and chest tightness 17.05%.
  • By occupation, pooled prevalence was 59.98% among cement factory workers and 58.6% among street sweepers.
  • In seven studies, workers with more than 5 years of work experience had higher odds of occupational respiratory symptoms than those working 5 years or less (pooled OR 2.24, 95% CI 1.21 to 4.16).
  • In eight studies, workers with primary education (Grade 8 and lower) had higher odds of symptoms than those with secondary education and above (pooled OR 1.28, 95% CI 1.06 to 1.55).
  • In nine studies, sex was not significantly associated with occupational respiratory symptoms.
  • The funnel plot and Egger's test (bias coefficient minus 0.1, p = 0.650) showed no evidence of publication bias or a small-study effect.
• The authors' conclusion: The authors concluded that the pooled prevalence of occupational respiratory symptoms was high and called for workplace safety measures. In their view, special attention was needed for employees with lower educational level and longer work experience.
• Limitations the authors state:
  • Considerable heterogeneity between the included studies.
  • Few participants, raising doubt about how representative the samples were of the national population.
  • No studies were available from most regions of Ethiopia.

Topics

Medical terms in this study, explained in our Lexicon: Systematic Review, Meta-Analysis.

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