Patient Safety Tip of the Week

July 20, 2010

More on the Weekend Effect/After-Hours Effect


We have discussed in several columns the increased incidence of adverse events and poor outcomes in the hospital at night and on weekends (see our Patient Safety Tips of the Week for February 26, 2008 “Nightmares….The Hospital at Night” and December 15, 2009 “The Weekend Effect” and our What’s New in the Patient Safety World columns for October 2008 “Hospital at Night Project” and September 2009 “After-Hours Surgery – Is There a Downside?”).


Our December 15, 2009 Patient Safety Tip of the Week “The Weekend Effect” discussed how adding nonclinical administrative tasks to already overburdened nursing staff on weekends may be detrimental to patient care. Now a new study from the UK (Temple 2010) suggests a physician component as well is part of “the weekend effect”. The study found the death rate at hospitals across England increased by 7% at weekends over the 2005-06 period. They ascribed the increased mortality rates on weekends to primarily two causes: (1) reliance on more junior physicians and (2) lack of specialist services.


To that we’d add a third contributing factor: physician cross-coverage is increased on weekends as well. That means that physicians who are much less knowledgeable about specific hospitalized patients may be covering.


A new systematic review and meta-analysis (Canallazzi 2010) found that there is an increased risk of death for patients admitted to an ICU over the weekend (about 8%) but not for those admitted at night. They suspect that organizational and staffing issues may explain the increased risk on weekends and note factors such as decreased physician-to-patient ratios, unavailability of board-certified intensivists, physician fatigue, and difficulty obtaining complex diagnostic tests as possible contributing factors.


Our September 2009 What’s New in the Patient Safety World column“After-Hours Surgery – Is There a Downside?”) noted a paper by Ricci et al showing that in orthopedic cases done “after hours” (4 PM to 6 AM) there was an increased need for reoperations for removal of painful fracture hardware. We discussed potential contributing factors such as loss of continuity of operating “teams”, different team dynamics, different staffing in postoperative areas, lack of familiarity with location of equipment, fatigue, lack of other support services (eg. radiology), etc.


Meanwhile, two recent studies using large national databases have looked at the influence of time of day and day of the week on perinatal outcomes. A Scottish study (Pasupathy 2010) showed about a 30% increased neonatal mortality for full-term deliveries taking place at all times other than Monday thru Friday from 9 AM to 5 PM. This was largely explained by an increased number of deaths attributed to intrapartum anoxia. After excluding elective Caesarean sections, the difference was attenuated but a significant association between time of delivery and outcome persisted.


A Dutch study (de Graaf 2010) found increased perinatal mortality and an increase in a combined perinatal adverse outcome measure in nontertiary hospitals during the evening and night and in tertiary hospitals at night.


Though the logical association here is with staffing patterns, neither study can directly link staffing patterns to the adverse outcomes and the authors of both studies point out that other factors may be important. While some past studies on time of day of deliveries had suggested fatigue as a potential factor, the fact that there was no difference between nighttime deliveries during weekdays and daytime deliveries on weekends in the Scottish study makes fatigue less likely an explanation.


It should be kept in mind that despite the increased rates of neonatal adverse events and deaths “after-hours”, the overall absolute numbers remain quite small. That must be taken into account in any cost-effectiveness considerations about staffing, etc. However, the authors of the Scottish study, which looked only at mortality, point out that one might expect the same effect of “after-hours” delivery on infants who survive and might have long-lasting neurological and developmental handicaps.


One factor often overlooked is the impact of shift work. Both nurses and physicians often work in shifts where the time of day worked varies and it is clear that such practices may have a number of detrimental effects in any industry. A nice discussion of this was provided in an article by the BMA Scottish Junior Doctors Committee. Though that paper was aimed at the hours worked by residents, they discuss the implications of shift work in numerous industries and the potential impact on safety and the potential health implications. One statistic they quote is that the estimated risk of reported adverse incidents in industry increases to 6% on the second night shift, 17% on a third, and 36% higher risk on a fourth night shift worked (the corresponding numbers for consecutive day shifts are 2%, 7% and 17%).


Lastly, one area in which there is almost no literature is the occurrence of adverse patient events at night and on weekends for outpatient care. Continuity of care often is often disjointed during such times, particularly when electronic medical records are not readily available to the covering physicians. We strongly suspect analysis of such care is likely to demonstrate a significant number of adverse events due to the unique problems encountered by covering physicians who have limited knowledge of the patients.






Temple J. Time for Training. A Review of the impact of the European Working Time Directive on the quality of training. May 2010



Cavallazzi R, Marik PE, Hirani A, et al. ssociation Between Time of Admission to the ICU and Mortality: A Systematic Review and Metaanalysis.

Chest 2010; 138: 68-75



Ricci WM, Gallagher B, Brandt A, Schwappach J, Tucker M, Leighton R. Is After-Hours Orthopaedic Surgery Associated with Adverse Outcomes? A Prospective Comparative Study. J Bone Joint Surg Am. 2009;91: 2067-2072



Pasupathy D, Wood AM, Pell JP, Fleming M, Smith GCS. Time of birth and risk of neonatal death at term: retrospective cohort study. BMJ  2010;341:c3498, doi: 10.1136/bmj.c3498 (Published 15 July 2010)


full text:



de Graaf J, Ravelli A, Visser G, Hukkelhoven C, Tong W, Bonsel G, Steegers E. Increased adverse perinatal outcome of hospital delivery at night. BJOG 2010; 17: 1098–1107



BMA Scotland. Shift-work, Rest and Sleep: Minimising the Risks

Discussion paper by the BMA Scottish Junior Doctors Committee

February 2010













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