Patient Safety Tip of the Week

October 24, 2017    Neurosurgery and Time of Day



We’ve done several columns highlighting the phenomenon that surgery done “after hours” may be associated with more complications than surgery done during normal daytime working hours (see the list of columns at the end of today’s column).


In our What's New in the Patient Safety World columns for September 2009 “After-Hours Surgery – Is There a Downside?” and October 2014 “What Time of Day Do You Want Your Surgery?” we discussed studies that showed for certain types of orthopedic surgery after hours there was an increased need for reoperations for removal of painful fracture hardware (Ricci 2009) and laparoscopic cholecystectomies done at night compared to daytime were associated with a higher conversion rate to open cholecystectomy (11% vs 6%) (Wu 2014). We also noted previous studies by Kelz and colleagues that showed increased morbidity in non-emergent surgical cases done “after hours”, one in the VA system (Kelz 2008) and another in a private hospital setting (Kelz 2009). And our January 2015 What's New in the Patient Safety World column “Emergency Surgery Also Very Costly” suggested, in addition to the human costs of after-hours surgery there may also be financial costs.


In our October 4, 2016 “More on After-Hours Surgery, we noted Canadian researchers (WFSA 2016) showed that surgical mortality does vary by time of day and that, after adjustment for age and ASA scores, patients operated at night (11:30 PM-7:29 AM) were 2.17 times more likely to die within 30 days than those operating on during regular daytime working hours (7:30 AM-3:29 PM). Those operated on in the late day (3:30 PM-11:29 PM) were 1.43 times more likely to die than those operated on during regular daytime working hours.


Now add to those previous studies a new one which looked at neurosurgical procedures at the University of Michigan Health System (Linzey 2017). Noting that reported outcomes are worse at night for things like coronary angioplasty, orthopedic surgery, and colorectal surgery, Linzey and colleagues reviewed their own experience in neurosurgery. There was a higher percentage of more minor procedures late in the day. As you’d expect, complications were more frequent in those cases done as “emergent” and in those patients with more comorbidities (likelihood of complications increasing 10% for each comorbidity). But after adjusting for all patient and procedure characteristics, the odds of a complication were increased by more than 50% for start times between 21:01 and 07:00 (OR 1.53). The odds ratio was even higher when severe complications were considered (OR 1.61).


Linzey and colleagues have some thoughtful comments on why a “night effect” might not have been seen in some reported series of transplant surgery. They noted that transplant surgery is done by teams who are used to working together and who frequently perform surgery at night. Transplant teams are also less reliant on housestaff. And transplant teams are typically doing one type of surgery, compared to other specialties which may be performing multiple different types of surgery at night.


Why should “after hours” surgery be more prone to adverse outcomes than regularly scheduled elective surgery? There are many reasons aside from the fact that patients needing emergency and after hours surgery are generally sicker. Obviously, fatigue (for all members of the surgical team) may be a factor. But for surgery, in particular, the impact of time of day on teamwork is important. You are often operating with a team that is likely different from your daytime team. All members of that team (physicians, nurses, anesthesiologists, techs, etc.) may not have the same level of expertise or experience as your regular daytime team (because many hospitals have “seniority” policies, you may have less experienced personnel on your OR “on-call” teams) and the team dynamics between members is likely to be different. The post-surgery recovery unit is likely to be staffed much differently after-hours as well. The staff may be more likely to be unfamiliar with things like location of equipment. And some of the other hospital support services (eg. radiology, laboratory, sterile processing, etc.) may have lesser staffing after-hours. Just as importantly, many or all of the “on-call” staff that make up the after-hours surgical team have likely worked a full daytime shift that day so fatigue enters as a potential contributory factor. And there are always time pressures after hours as well. In addition, one of the most compelling reasons surgery is done at night rather than deferred to the next morning is the schedule of the surgeon or other physician for that next morning (either in surgery or the cath lab or his/her office). Because the surgeon does not want to disrupt that next day schedule, he/she often prefers to go ahead with the current case at night. Similarly, many hospitals run very tight OR schedules and adding a case from the previous night can disrupt the schedule of many other cases.


All of this, of course, needs to be balanced against the need to do truly emergent cases as soon as possible. In our August 15, 2017 Patient Safety Tip of the Week “Delayed Emergency Surgery and Mortality Risk” we noted a study (McIsaac 2017) showing that delays in performing emergent cases were associated with increased mortality (OR 1.56), increased length of stay (incident rate ratio 1.07), and higher total costs.


We highly recommend hospitals take a hard look at surgical cases done “after hours”. You need to look at the morbidity and mortality statistics of such cases. In particular, you need to determine which cases truly needed to be done after hours (emergency cases) and, perhaps more importantly, which ones could have and should have been done during “regular hours”. If the latter are significant, you need to consider system changes such as reserving some “regular hours” for such cases to be done the following morning. You may have to alter the scheduling of cases for individual surgeons as well. For example, perhaps the surgeon on-call tonight should not have elective cases scheduled tomorrow morning. That way, if a case comes in tonight that should be done tomorrow morning you will have both a “free” OR room and a “free” surgeon. And you would need to develop a list of criteria to help you triage cases into “regular” or “after-hours” time slots.




Some of our previous columns on “after-hours” surgery:

·         September 2009         After-Hours Surgery – Is There a Downside?

·         October 2014             What Time of Day Do You Want Your Surgery?

·         January 2015             Emergency Surgery Also Very Costly

·         September 2015         Surgery Previous Night Does Not Impact Attending Surgeon Next Day

·         October 4, 2016         More on After-Hours Surgery

·         August 15, 2017        Delayed Emergency Surgery and Mortality Risk







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



Wu JX, Nguyen AT, de Virgilio C, et al. Can it wait until morning? A comparison of nighttime versus daytime cholecystectomy for acute cholecystitis. Amer J Surg 2014; published online first September 20, 2014



Kelz, R.R., Freeman, K.M., Hosokawa, P.W. et al. Time of day is associated with postoperative morbidity: an analysis of the national surgical quality improvement program data. Annals of Surgery 2008; 247: 544–552



Kelz RR, Tran TT, Hosokawa P, et al. Time-of-day effects on surgical outcomes in the private sector: a retrospective cohort study. J Am Coll Surg 2009; 209(4): 434-445.e2.



WFSA (World Federation of Societies of Anaesthesiologists). Five-year study reveals patients operated on at night twice as likely to die as patients who have daytime operations. Science Daily 2016; August 29, 2016


Wang N, et al. Retrospective analysis of time of day of surgery and its 30 day in-hospital postoperative mortality rate at a single Canadian institution. Poster presentation 601. World Congress of Anaesthesiologists 2016



Linzey JR, Burke JF, Sabbagh A, et al. The Effect of Surgical Start Time on Complications Associated With Neurological Surgeries. Neurosurgery 2017; Published online 13 October 2017



McIsaac DI, Abdulla K, Yang H, et al. Association of delay of urgent or emergency surgery with mortality and use of health care resources: a propensity score–matched observational cohort study. CMAJ 2017; 189: E905-E912 published online July 10, 2017







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