What’s New in the Patient Safety World

June 2013

Oh No! Not Fridays Too!



The “weekend effect” is a term used to refer to an increase in untoward events or suboptimal outcomes occurring in patients admitted to hospitals over the weekend. In some cases we use the term “after hours effect” since some of the same issues occur in patients admitted at night. We’ve discussed the numerous factors that may contribute to the “weekend effect” in our previous columns listed at the end of today’s column.


Various studies have demonstrated higher mortality rates for patients admitted on weekends with strokes, atrial fibrillation, diverticulosis surgery, a variety of other surgical procedures, head trauma, COPD, CHF, perinatal events, ICU admissions, ESRD, and other conditions. In fact, in our June 2011 What’s New in the Patient Safety World “Another Study on Dangers of Weekend Admissions” we noted a study (Ricciardi 2011) that found that mortality rates were higher for 15 of 26 major diagnostic categories when patients were admitted on weekends. Even after adjustment for comorbidities and a variety of other clinical and demographic characteristics there remained a significant increase in mortality, on the order of 10% higher for those admitted on weekends.


Now a new study (Aylin 2013) from the UK evaluated mortality for patients undergoing elective surgical procedures by day of the week and found the risk of death was 44% higher for surgery done on Fridays and 82% higher for those done on weekends compared to surgery done on Mondays. This occurred despite patients operated upon on Fridays and weekends having fewer comorbidities than those operated upon on Mondays.


A previous study done in the VA system in the US (Zare 2007) found that for patients admitted to regular hospital floors after non-emergent major surgery, mortality was increased if surgery is performed on Friday versus Monday through Wednesday. After adjusting for patient characteristics, odds ratio of 30-day mortality for operations on Fridays was 17% higher than for operations on Mondays through Wednesdays.


The perioperative period is one of greatest vulnerability for most patients undergoing surgery. So it is not surprising that we might expect more complications on the several days following surgery, whether elective or emergent. Since most of the postoperative care for patients having surgery on Fridays will actually occur over the weekend, it’s logical to attribute this Friday phenomenon to “the weekend effect” (but see below for other key considerations).


Our healthcare systems clearly do not deliver uniform care 24x7. The differences between the hospital during weekday daytime hours and the hospital at night and on weekends is striking. Staffing patterns (both in terms of volume and experience) are the most obvious difference but there are many others as well. Many diagnostic tests are not as readily available during these times. Physician and consultant availability may be different and cross-coverage by physicians who lack detailed knowledge about individual patients is common. You also see more verbal orders, which of course are error-prone, at night and on weekends.


But often it is the difference in non-clinical staffing that is a root cause. Our December 15, 2009 Patient Safety Tip of the Week “The Weekend Effect” discussed how adding non-clinical administrative tasks to already overburdened nursing staff on weekends may be detrimental to patient care. Just do rounds on one of your med/surg floors or ICU’s on a weekend. You’ll see nurses answering phones all day long, causing interruptions in some attention-critical nursing activities. Calls from radiology and the lab that might go directly to physicians now go first to the nurse on the floor, who then has to try to track down the physician. They end up filing lab and radiology reports or faxing medication orders down to pharmacy, activities often done by clerical staff during daytime hours. Even in those facilities that have CPOE, nurses off-hours often end up entering those orders into the computer because the physicians are off-site and are phoning in verbal orders. You’ll also see nurses giving directions to the increased numbers of visitors typically seen on weekends. They even end up doing some housekeeping chores. All of these interruptions and distractions obviously interfere with nurses’ ability to attend to their clinically important tasks (see our Patient Safety Tips of the Week for August 25, 2009 “Interruptions, Distractions, Inattention…Oops!” and May 4, 2010 “More on the Impact of Interruptions”).


While staffing levels have attracted the most attention in attempt to explain “the weekend effect”, there may be other factors that are important. Consecutive days worked may also play a role and this could apply to surgeons as well as all other members of the OR team. Our November 9, 2010 Patient Safety Tip of the Week “12-Hour Nursing Shifts and Patient Safety” cited a study on shift workers in fields other than healthcare (Folkard 2003) which showed that the risk of incidents increased each consecutive day worked. For example, on average for night shifts risk was 6% higher on the second night, 17% higher on the third night, and 36% higher on the fourth night. While most people reading that article focus on those night shift statistics, the corresponding risks for morning/day shifts were 2%, 7% and 17%. So it is clear that risks in most industries increase with consecutive days worked. In fact, in the Aylin study mortality increased in a linear fashion by a factor of 1.09 for each day beyond Monday. So it is hard to ignore the parallel between the consecutive days worked statistics and the pattern of mortality seen by day of the week.



As noted in the editorial accompanying the Aylin study (Kwan 2013) maybe we need to think twice about the adage “thank goodness it’s Friday”! Guess what! If we ever need elective surgery, we aren’t going to have it on a Friday even if that’s the most convenient day for us!




Some of our previous columns on the “weekend effect:







Ricciardi R, Roberts PL, Read TE, et al. Mortality Rate After Nonelective Hospital Admission. Arch Surg. 2011; 146(5): 545-551




Aylin P, Alexandrescu R, Jen MH, et al. Day of week of procedure and 30 day mortality for elective surgery: retrospective analysis of hospital episode statistics. BMJ 2013; 346: f2424




Zare MM, Itani KMF, Schifftner TL, Henderson WG, Khuri SF. Mortality after nonemergent major surgery performed on Friday versus Monday through Wednesday. Ann Surg 2007; 246: 866-74




Folkard S, Tucker P. Shift work, safety and productivity. Occupational Medicine 2003; 53: 95-101




Kwan JL, Bell CM. Should we rethink the scheduling of elective surgery at the weekend?

BMJ 2013; 346: f3353 (Published 28 May 2013)






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