Objective To examine the magnitude of the weekend effect, defined as differences in patient outcomes between weekend and weekday hospital admissions, and factors influencing it.
Design A systematic review incorporating Bayesian meta-analyses and meta-regression.
Data sources We searched seven databases including MEDLINE and EMBASE from January 2000 to April 2015, and updated the MEDLINE search up to November 2017. Eligibility criteria: primary research studies published in peer-reviewed journals of unselected admissions (not focusing on specific conditions) investigating the weekend effect on mortality, adverse events, length of hospital stay (LoS) or patient satisfaction.
Results For the systematic review, we included 68 studies (70 articles) covering over 640 million admissions. Of these, two-thirds were conducted in the UK (n=24) or USA (n=22). The pooled odds ratio (OR) for weekend mortality effect across admission types was 1.16 (95% credible interval 1.10 to 1.23). The weekend effect appeared greater for elective (1.70, 1.08 to 2.52) than emergency (1.11, 1.06 to 1.16) or maternity (1.06, 0.89 to 1.29) admissions. Further examination of the literature shows that these estimates are influenced by methodological, clinical and service factors: at weekends, fewer patients are admitted to hospital, those who are admitted are more severely ill and there are differences in care pathways before and after admission. Evidence regarding the weekend effect on adverse events and LoS is weak and inconsistent, and that on patient satisfaction is sparse. The overall quality of evidence for inferring weekend/weekday difference in hospital care quality from the observed weekend effect was rated as ‘very low’ based on the Grading of Recommendations, Assessment, Development and Evaluations framework.
Conclusions The weekend effect is unlikely to have a single cause, or to be a reliable indicator of care quality at weekends. Further work should focus on underlying mechanisms and examine care processes in both hospital and community.
Prospero registration number CRD42016036487
- weekend effect
- adverse events
- systematic review
- Bayesian meta-analysis
- healthcare databases
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Contributors Y-FC led the preparation of the review, contributed to all stages from conceptualisation to drafting the manuscript of the review and is the guarantor; XA contributed to all stages (except data analysis) of the review; CH, NC and RB contributed to data extraction and quality assessment; SIW planned and carried out Bayesian analyses; AB contributed to literature search, study screening and coordination; CT and ES contributed to development of review methods and study screening; C-WW contributed to data checking; CPA contributed to development of review methods and managerial support; AG contributed to study coding; RL contributed to development of review methods and provided senior advice; JB contributed to development of review methods, provided senior advice and is the principal investigator for the HiSLAC project. All authors commented on draft manuscripts and approved the final version.
Funding The High-intensity Specialist Led Acute Care (HiSLAC) project is funded by the NIHR Health Services and Delivery Research (HS&DR) Programme (Project No. 12/128/17). Y-FC, SIW and RL are supported by the NIHR Collaboration for Leadership in Applied Health Research and Care (CLAHRC) West Midlands.
Competing interests None declared. The views and opinions expressed herein are those of the authors and do not necessarily reflect those of the HS&DR Programme, NIHR, National Health Services or the Department of Health.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement All data relevant to the study are included in the article or uploaded as supplementary information.
Patient consent for publication Not required.
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