'Weekend Effect' in Hospital Deaths Is Oversimplified

Marcia Frellick

May 10, 2016

Two new studies published online today in the Lancet call into question previous reports that suggest weekend staffing at hospitals is linked to higher patient mortality.

One study looked specifically at acute stroke care and found no weekend effect on mortality, but found quality of care is inconsistent throughout the week. Therefore, the authors say, addressing only weekend care oversimplifies the problem. The second study found no correlation between weekend specialty staffing and patient deaths.

The two papers add evidence to a report published last week that suggested weekend mortality differences might have more to do with how sick patients are on admission than the care they receive.

In the study on acute stroke, Benjamin Bray, MD, from the Farr Institute of Health Informatics Research at the University College London in the United Kingdom, and colleagues studied outcomes for 74,307 patients with acute stroke admitted to 199 hospitals.

They found that care quality varied by day of the week and time of day. For instance, "patients arriving in the morning were more likely to receive a brain scan within 1 h than were those admitted in the afternoon," they write.

They identified several patterns of variations in care and found that one quality measure — door-to-needle time within 60 minutes — had a particularly strong link to day of week and time of day, and that it was worse over nights and on weekends.

"We believe this pattern could be due to loss of spare bed capacity over the weekend as a result of reduced frequency of hospital discharges, resulting in the slowest transfers to stroke units occurring on Mondays," the authors write.

Also, patients admitted on Thursdays and Fridays waited longest for therapy assessment.

The authors found no difference in adjusted 30-day survival between patients who were admitted during weekend daytime and those admitted on weekdays in the models. However, they did find weak evidence that survival was worse for patients admitted overnight on weekdays (adjusted odds ratio, 0.90 [95% confidence interval (CI), 0.82 - 0.99]; absolute difference in adjusted survival, −0.7% [95% CI, −1.2% to −0.2%).

"Although this study is of the quality of care received by people with acute stroke, it seems unlikely that stroke care alone displays such patterns of temporal variation in quality," the authors write. "Extension of this methodology to other areas of health care would be useful...particularly for presentations for which the timeliness of care is an important determinant of outcomes (such as acute myocardial infarction or surgical emergencies)."

Wednesday vs Sunday Care

In the second study, Cassie Aldridge, PhD, from the University of Birmingham in the United Kingdom, and colleagues used a point prevalence survey to find out about the availability of specialists and the care provide they provided for emergency admissions on Sunday June 15 and Wednesday June 18, 2014.

The results included data from 115 hospital trusts (91% of those eligible) and 15,537 specialists (45% of those eligible).

Overall, they found a substantial difference between weekend and weekday specialist involvement in caring for patients admitted as emergencies to acute hospitals in England. For example, substantially fewer specialists were available to provide care on Sundays (1667 [11%]) compared with on Wednesday (6105 [42%]).

Partially offsetting that, however, was the finding that specialists present on Sunday spent 40% more time caring for emergency patients than did those present on Wednesday (mean, 5.74 hours [standard deviation, 3.39] vs 3.97 hours [standard deviation, 3.31]). On Sunday, the specialist intensity, defined as the number of specialists hours between 0800 and 2000 h for each 10 emergency admissions, was 48% of that on Wednesday.

Despite the variation in care, the authors found no link between risk for death and weekend staffing.

"We are unable to demonstrate an association between specialist staffing and mortality, but would not necessarily expect to do so in the first year of a 5 year longitudinal study," the authors write. "However, this finding suggests the need for caution in attributing the weekend effect mainly to a lack of consultants at weekends."

In an accompanying editorial, Nick Black, MD, from the Department of Health Services Research and Policy, London School of Hygiene & Tropical Medicine, United Kingdom, concludes that "caution should be taken in estimating the effect on mortality. Previous studies based on routine administrative data did their best to use inventive and sophisticated methods to take casemix difference between weekends and weekdays into account, but had little information about how sick patients were on admission."

What is really needed is a study that accounts for patients' severity of illness at admission, he writes.

He adds that because only a small percentage of deaths are avoidable, researchers should perhaps look at factors such as morbidity, length of stay, and quality-of-life and safety aspects of the patient experience, and how they are affected by staffing.

In addition, perhaps it is not the physician staffing, but nurse staffing or diagnostic staffing, that has a bigger effect on outcomes, he says, or combinations of different staffing levels.

"But even that approach might not be sufficient because research on inputs, such as staffing levels, risks missing the processes of care, known to be the key determinants of poor quality care," he writes.

He concludes, "Despite many claims about the quality of care at weekends and strong beliefs about the reasons for this, we need to remain open to the true extent and nature of any such deficit and to the possible causes. Jumping to policy conclusions without a clear diagnosis of the problem should be avoided because the wrong decision might be detrimental to patient confidence, staff morale, and outcomes."

In the study by Dr Aldridge and colleagues, one coauthor is the chair of the National Institute for Health and Care Excellence Acute Medical Emergencies Guideline Development Group, National Clinical Guideline Centre.The study received funding from the National Institute for Health Research Health Services and Delivery Research Programme. In the study by Dr Bray and colleagues, coauthors have received personal fees and nonfinancial support from Boehringer Ingelheim outside the submitted work. One coauthor is trustee and medical vice chair of the Stroke Association, as well as associate director of the Royal College of Physicians Stroke Programme. All other authors have disclosed no relevant financial relationships.

Lancet. Published online May 10, 2016. Aldridge abstract, Bray abstract

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