'Weekend Effect' Observed in Obstetric Care in Large Study

Diana Phillips

November 25, 2015

Obstetric outcomes for women admitted and infants born on a weekend day were worse than for those with weekday admissions and births, according to an observational study of more than 1.3 million deliveries.

"[B]abies born at the weekend had an increased risk of being stillborn or dying in hospital within the first seven days," William L. Palmer, MA, MSc, from the Dr Foster Unit, Department of Primary Care and Public Health, Imperial College London, and the National Audit Office, London, United Kingdom, and colleagues report in an article published November 24 in in the BMJ. "Moreover, the results also suggest increases in the rates of other complications for both women admitted and babies born at weekends, with higher rates of puerperal infection, injury to neonate, and three day neonatal emergency readmissions."

Although the study design precludes definitive conclusions about causation, the apparent "weekend effect," which has been observed internationally across medical conditions, warrants additional research into organizational factors that might to contribute to quality-of-care disparities between weekday and weekend obstetrical admissions, the authors stress.

To investigate the possible association between day of delivery and the quality and safety of obstetric care, the investigators examined outcomes for 1,332,835 deliveries and 1,349,599 births between April 1, 2010, and March 31, 2012, included in the nationwide administrative data set. They looked specifically at outcomes across seven quality and safety indicators: perineal tear, puerperal infection, and 3-day emergency readmission for mothers, and in-hospital perinatal mortality, injury to neonate, selected neonatal infections, and 3-day emergency readmissions for newborns.

"We found statistically significant associations in four of the indicators, all of which were consistent with a lower standard of care for women admitted and babies born at weekends," the authors write.

The largest effects were seen in perinatal mortality (adjusted odds ratio [aOR], 1.07; 95% confidence interval [CI], 1.02 - 1.13), puerperal infections (aOR, 1.06; 95% CI, 1.01 - 1.11), injury to neonate (aOR, 1.06; 95% CI, 1.02 - 1.09), and 3-day neonatal readmissions (aOR, 1.04; 95% CI, 1.00 - 1.08).

Of note, the perinatal mortality rate was 7.3 per 1000 babies delivered on weekends, which is 0.9 per 1000 higher than that observed for weekdays. As such, the authors estimate this translates to 770 newborn deaths above what could be expected if performance were consistent across days of the week.

The investigators also explored the association between outcomes and staffing levels in the hospital obstetrical services.

"Within the maternity data extract, 51 [39.8%] of the 128 units were compliant with the recommended level of consultant presence," they report. Statistically significant differences in outcomes between compliant and noncompliant units were observed in rates of perineal tears (aOR, 1.21, 95% CI, 1.00 - 1.45), but not for any other indicators.

"Further work is needed to understand what organisational factors might influence the weekend effect and to investigate centres that have reduced the disparities in access and outcome in out of hours care," the authors write, advocating for better data and an out-of-hours admission flag for hospital administrative data.

"Unless managers and practitioners work to better understand and tackle the problems raised in this paper, health outcomes for mothers and babies are likely to continue to be influenced by the day of delivery," the authors stress.

In an accompanying editorial, Jonathan M. Snowden, PhD, and Aaron B. Caughey, MD, PhD, from the Department of Obstetrics and Gynecology and School of Public Health, Oregon Health and Science University, write that the most likely mechanisms underlying the weekend effect observed in this and other studies are system factors such as staffing, resource availability, and hospital policies, which tend to be healthcare system– and even hospital-specific. "Therefore, finding evidence of an effect in one population does not guarantee that the association will persist in others or even within a single population over time," they note.

"The weekend effect in obstetrics fits within the broad concept of 'capacity strain' in healthcare systems — the process by which performance of a clinical unit can deteriorate above a certain threshold of patient volume, complexity (acuity), or both," the editorialists write. "Given the decreased levels of staffing and availability of resources that characterize most hospitals at the weekend, a lower threshold above which capacity strain threatens patients' outcomes is likely." This and other forms of capacity strain in obstetric units may be mitigated by innovative, flexible staffing models, such as the obstetric hospitalist model, as well as condition-specific protocols and other policy-level initiatives at the hospital level.

The authors and editorialists have disclosed no relevant financial relationships.

BMJ. 2015;351:h6192. Article full text, Editorial full text

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