Intended for healthcare professionals

Research News

“Weekend effect” is due to patient differences rather than staffing levels, study concludes

BMJ 2017; 357 doi: (Published 12 May 2017) Cite this as: BMJ 2017;357:j2331
  1. Jacqui Wise
  1. London

The “weekend effect” on mortality arises from patient level differences at admission rather than reduced hospital staffing or services, research published in the Lancet concludes.1

Substantial medical and media attention has been paid to the weekend effect—namely, that patients admitted to hospital at a weekend have greater mortality than patients admitted on weekdays.

In 2015 the health secretary, Jeremy Hunt, claimed that 6000 avoidable deaths occurred each year and that a lack of weekend cover by consultants was a key factor. He cited various studies to support the government’s push to improve hospital services on Saturdays and Sundays and to justify imposing new contracts on junior doctors.234

Sarah Walker, of the Oxford Biomedical Research Centre, and colleagues analysed unselected emergency admissions to four large Oxford hospitals from January 2006 to December 2014. During that period 257 596 patients underwent 503 938 admissions: the study found that 18 313 patients (4.7%) who were admitted as weekday emergency admissions and 6070 patients (5.1%) admitted at the weekend died within 30 days (P<0.001).

The researchers adjusted for factors not considered in other studies, including haematology and biochemistry tests such as median neutrophil count and C reactive protein. In 271 465 admissions for which complete data existed (53.9% of the total), these test results strongly and independently predicted 30 day mortality. The study found that adjustment for 15 routinely measured haematology and biochemistry test results accounted for 33% of the excess mortality on Saturdays and 52% of the excess mortality on Sundays.

The residual “weekend effect” was predominantly restricted to the middle of the day on Saturdays and Sundays (11 am to 3 pm), and no excess mortality was found on weekend nights. In addition, excess mortality at the weekend was not associated with multiple measures of hospital workload, including staffing levels.

The researchers also found that 9347 patients underwent 9707 admissions on public holidays, and 559 (5.8%) died within 30 days. In this group, adjustment for the 15 biochemistry and haematology tests accounted for 87% of the excess mortality.

“Because staffing levels and services are more similar on public holidays and weekends, it seems unlikely that differences in staffing levels or services alone would explain the excess mortality associated with weekend versus weekday admission,” the authors said.

They noted that access to senior staff, imaging, and other diagnostic tests is similar throughout the weekend. They said that their observation that the weekend effect was restricted to admissions in the middle of the day may be due to the availability of services outside hospital or differences in health seeking behaviour at weekends.

A limitation of the study is that the researchers had no access to patients’ vital signs or direct measures of acute illness severity. They said that much of the remaining excess risk may be explained by accounting for other patient level factors.

They concluded, “Increased mortality in patients admitted between 1100h and 1500h at weekends might not be preventable through implementation of 7-day hospital services. By contrast, the unintended consequence of patients delaying presenting to hospital because of fears of worse care at the weekends poses a clear, avoidable danger.”

Tim Peto, professor of medicine at the University of Oxford and a coauthor, added, “As well as these 15 blood tests [adjusted for in the study], patients admitted at weekends could also differ in their vital signs (fever, blood pressure, etc). They may also have different reasons for coming to hospital at weekends, including lack of other services such as social care outside the hospital.

“Our study found that the ‘weekend effect’ is more likely to come from differences in how sick individual patients are at admission, rather than reduced hospital staffing or services. So patients should feel safe to attend hospital on any day.”


View Abstract

Log in

Log in through your institution


* For online subscription