Work-relatedness of inguinal hernia: a systematic review including meta-analysis and GRADE

Purpose: Clinicians need to know whether inguinal hernia (IH) can be attributed to work to answer questions regarding prevention and medical causation. This review describes whether work-related risk factors are associated with IH. Methods: A systematic review was performed in Medline via PubMed until February 3rd, 2020. Inclusion criteria were that IH was diagnosed by a clinician, and workers exposed to work-related risk factors were compared to workers less exposed or not at all. A quality assessment and a meta-analysis using Cochrane’s RevMan 5.3 were performed, including GRADE for quality of evidence. Results: The search resulted in 540 references. Fourteen studies fulfilled the inclusion criteria, of which three were included in a meta-analysis, all three being of high quality, including 621 workers diagnosed with IH. The meta-analysis revealed significant associations with physically demanding work (OR 2.30, 95% CI 1.56–3.40). Two prospective studies, including 382 and 22,926 cases revealed associations that this was true for male workers with a lateral IH that reported standing or walking for more than six hours per workday (OR 1.45, 95% CI 1.12–1.88) or lifting cumulative loads of more than 4000 kg per workday (OR 1.32, 95% CI 1.27–1.38). The level of certainty for the latter two work-related risk factors was moderate and high according to GRADE. Conclusion: Lateral IH among males is associated with work-related risk factors depending on the level of exposure to the time standing/walking per workday, or the amount of load lifted per workday.