Sicker patients account for the weekend mortality effect among adult emergency admissions to a large hospital trust

Research output: Contribution to journalArticlepeer-review


  • Jianxia Sun
  • Cassie Aldridge
  • Felicity Evison
  • Chris Beet
  • Gavin Rudge
  • Richard J. Lilford

Colleges, School and Institutes


Objective: To determine whether the higher weekend admission mortality risk is attributable to increased severity of illness.

Design: Retrospective analysis of 4 years weekend and weekday adult emergency admissions to a university teaching hospital in England.

Outcome Measures: 30-day post-admission weekend:weekday mortality ratios adjusted for severity of illness (baseline National Early Warning Score), routes of admission to hospital, transfer to the Intensive Care Unit (ICU), and demographics.

Results: Despite similar emergency department (ED) daily attendance rates, fewer patients were admitted at weekends (mean admission rate 91/d vs 120/d), because of fewer general practitioner referrals. Weekend admissions were sicker than weekday (mean NEWS 1.8 vs 1.7, p=0.008), more likely to undergo transfer to ICU within 24h (4.2%; 3.8/d versus 3.0%; 3.6/d), spent longer in hospital (median 3d vs 2d), and less likely to experience same day discharge (17.2% vs 21.9%) (all p values <0.001).

The crude 30-day post-admission mortality ratio for weekend admission (OR=1.13; CI 1.08-1.19) was attenuated using standard adjustment (OR=1.11; CI 1.05-1.17). In patients for whom NEWS values were available (90%), the crude OR (1.07; CI 1.01-1.14) was not affected with standard adjustment. Adjustment using NEWS alone nullified the weekend effect(OR=1.02; 0.96-1.08).

NEWS completion rates were higher at weekends (91.7%) than weekdays (89.5%). Missing NEWS was associated with direct transfer to intensive care bypassing electronic data capture. Missing NEWS in non-ICU weekend patients was associated with a higher mortality and fewer same-day discharges than weekdays.

Conclusions: Patients admitted to hospital at weekends are sicker than those admitted on weekdays. The cause of the weekend effect may lie in community services.


Original languageEnglish
Number of pages8
JournalBMJ Quality & Safety
Early online date9 Oct 2018
Publication statusE-pub ahead of print - 9 Oct 2018


  • mortality (standardized mortality ratios), patient safety, duty hours/work hours, emergency department, hospital medicine