Shift work and long work hours and their association with chronic health conditions: A systematic review of systematic reviews with meta-analyses.
Level 1 - systematic review of randomized trials
Systematic review of systematic reviews with meta-analyses
PubMed 32240254 · doi:10.1371/journal.pone.0231037
What was done
Authors conducted an umbrella systematic review of systematic reviews with meta-analyses (SR-MAs; PROSPERO CRD42019122084) examining associations between shift work or long work hours and chronic health outcomes. They synthesized 48 SR-MAs covering cancers, cardiovascular diseases, metabolic syndrome, pregnancy complications, depression, hypertension, and injuries. Review quality was appraised using AMSTAR v2 (16 items), and body-of-evidence certainty was assessed using the GRADE framework.
What was found
The abstract reports no numerical effect sizes or risk ratios, reporting instead review quality and GRADE certainty tiers: - Included SR-MAs fulfilled an average of only 7 of 16 AMSTAR quality items; few had registered protocols and nearly all failed to conduct comprehensive searches. - Moderate-grade evidence linked shift work to breast cancer and long work hours to stroke. - Low-grade evidence linked both shift work and long work hours to low-to-moderate risk increases for some pregnancy complications and cardiovascular diseases, and long work hours to depression. - Evidence for all other examined chronic conditions was unclear.
Why it matters
This umbrella review shows that despite a large literature on non-standard work schedules, methodological quality across published meta-analyses is generally poor, with moderate-certainty evidence currently established only for breast cancer (shift work) and stroke (long hours).
Limits
The abstract provides no numerical effect estimates (e.g., relative risks or odds ratios), confidence intervals, or underlying participant totals. The primary evidence base is observational, and the constituent systematic reviews predominantly displayed low methodological rigor (fulfilling <50% of AMSTAR criteria on average).
Cited by
- supports People who work night shifts over long periods have a significantly higher risk of metabolic disease and cancer.