Safety incidents associated with extended working hours. A systematic review and meta-analysis

OBJECTIVE: We performed a systematic review to assess potential consequences of extended working hours on accidents, near-accidents, safety incidents and injuries (hereafter ’incidents’) by considering the overall certainty of evidence. METHODS: We searched five databases systematically (Medline, Embase, PsycINFO, Web of Science, and Proquest Health and Safety Science Abstracts) and identified 10 072 studies published up to December 2020, 22 of which met the inclusion criteria. We followed a systematic approach to evaluate risk of bias and synthesize results in a meta-analysis. The certainty of evidence was determined by a modified version of the Grading of Recommendations Assessment, Development and Evaluation (GRADE). RESULTS: Our analyses indicated an association between working >12 hours/day [relative risk (RR) 1.24, 95% confidence interval (CI) 1.11–1.40], or working >55 hours/week (RR 1.24, 95% I 0.98–1.57), and elevated risk of incidents. The certainty of evidence evaluated as low. Weak or no associations were observed for other exposure contrasts: working >8 hours/day (RR 0.93, 95% CI 0.72–1.19), or working overtime (RR 1.08, 95% CI 0.75–1.55), working 41–48 hours/week (RR 1.02, 95% CI 0.92–1.13) or 49–54 hours/week (RR 1.02, 95% CI 0.97–1.07). The certainty of evidence was evaluated as low (very low for 41–48 hours/week). CONCLUSIONS: Daily working hours >12 hours and weekly working hours >55 hours was associated with an increased risk of incidents. The certainty of evidence was low. Hence, further high-quality research is warranted to elucidate these associations.