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.