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The increased mortality observed if patients are taken to hospitals at weekends also affects night admissions and can be explained in part by the severity of illness.

Five linked NIHR-funded studies reviewed mortality and time and day of admission to hospital, largely using routine England-wide data.

Fewer people are admitted from A&E at the weekend. Admission is more likely if they have arrived by ambulance or been referred directly for admission from community services. Though death rate within 30 days was slightly higher for these admissions, it is likely that this was due to more severe illness. There was no difference in mortality for people who attended A&E but were not admitted.

NHS Trusts have been told by NHS England to reorganise services in line with “seven day working” to eliminate the weekend effect. These studies raise doubts as to whether such a reorganisation will achieve a reduction in mortality overall.

Why was this study needed?

Patients admitted to hospital outside of normal working hours, at night or during weekends, are more likely to die than those admitted during working hours. It is not clear why this is.

One possibility is that the NHS is understaffed at weekends, with a dearth of senior staff and services. Another is that patients admitted at weekends are more severely ill, meaning their chances of survival are lower. There is a lack of clarity about the causes of the “weekend effect”.

NHS England has instructed trusts to reorganise to provide seven-day services. However, it is unclear how costly this would be, what effect it would have on weekend mortality, and what knock-on affects it might have on weekday mortality.

This study aimed to answer some of these questions.

What did this study do?

Researchers carried out a series of retrospective analyses of hospital episode statistics data in England. They looked at data for all emergency admissions and A&E attendances between 1 April 2013 and 31 March 2014, and between 1 April 2010 and 31 March 2011. Specifically, they determined whether time and day of admission affected 30-day mortality.

Further analysis was performed on records of 244,639 emergency admissions to the Salford Royal NHS Foundation Trust between April 2004 and March 2014. Stroke outcomes depending on nurse staffing levels were determined between January 2009 and July 2014.

The research is limited by retrospective data availability and accuracy. In particular, there was little information on deaths that occurred out of hospital.

What did it find?

According to national data:

  • Weekday emergency admissions have a slightly lower rate of death within 30 days of 3.7% compared to 4.05% for weekend admissions.
  • There are fewer emergency admissions from A&E at the weekend (27.5% versus 30%). Those admitted have more severe illness and a slightly higher mortality rate than those admitted via A&E during the week (odds ratio [OR] 1.054, 95% confidence interval [CI] 1.040 to 1.069).
  • People admitted at night and weekends are more likely to arrive by ambulance, a further indication that they may be sicker. Those who self-refer to A&E at the weekend and are not admitted have no increased 30-day mortality risk compared to those attending during weekdays (OR 1.010, 95% CI 0.997 to 1.022).
  • There are 61% fewer direct admissions from services in the community at the weekend, but they have a slightly higher rate of death within 30 days of 2.72% versus 2.37% for weekday direct admissions (difference 0.35%, 95% CI 0.21 to 0.46).
  • A basic analysis of costs and potential benefits of introducing fully-staffed seven-day services England-wide suggested it would cost £1.1 to £1.4 billion each year, with a potential maximum benefit of 29,727 to 36,539 quality-adjusted life years (QALY) per year.

What does current guidance say on this issue?

NHS England has published 10 clinical standards for seven-day services in hospitals. Four have been identified as priorities:

  • Patients should be assessed by a consultant within 14 hours of admission to hospital.
  • Hospital inpatients must have scheduled seven-day access to diagnostic services such as ultrasound, CT scans and microbiology.
  • Hospital inpatients must have timely 24-hour access, seven days a week, to key consultant-directed interventions that meet the relevant speciality guidelines, such as critical care, interventional radiology and emergency general surgery.
  • All patients with high dependency needs should be seen and reviewed by a consultant twice daily.

What are the implications?

Taken together, these studies call into question the causes of the weekend effect and the potential impact on mortality of moves towards seven day working in the NHS. There may be other reasons that change is needed.

Data from local and national level suggests that some of the weekend effect is moderated by differences in severity between patients admitted to hospital during normal working hours and at night or weekends. Higher staffing levels, therefore, may not eradicate the differences in mortality rates between normal and out of hour’s admissions.

Reorganisation of services to meet a 24-hour, seven-day service is likely to be costly. Estimates from early adopter trusts in one of the studies suggest costs in the billions, with a commensurately high cost per QALY – even if seven day working could eradicate all excess deaths, which is doubtful.

Citation and Funding

Han L, Meacock R, Anselmi L, et al. Variations in mortality across the week following emergency admission to hospital: linked retrospective observational analyses of hospital episode data in England, 2004/5 to 2013/14. Health Serv Deliv Res. 2017;5(30).

This project was funded by the Health Services and Delivery Research (HS&DR) programme, part of the National Institute for Health Research (NIHR).



Han L, Sutton M, Clough S, et al. Impact of out-of-hours admission on patient mortality: longitudinal analysis in a tertiary acute hospital. BMJ Qual Saf. 2017. [Epub ahead of print].

NHS Improvement. Seven day services in the NHS. London: NHS Improvement; updated April 2017.

Produced by the University of Southampton and Bazian on behalf of NIHR through the NIHR Dissemination Centre


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