The patients who underwent a neurosurgical procedure between 9 pm and 7 am were at an increased risk of developing complications compared to patients who started surgery earlier in the day. The study was published in Neurosurgery.

In earlier studies, the relationship between the surgical and medical management of diseases at night leading to a worse outcome has been demonstrated in those undergoing: coronary angioplasty, transplant surgery, orthopedic surgery, cardiac arrest, and colorectal surgery. The main aim of the current study was to understand the relationship of the surgical start time to the development of neurosurgical morbidity and mortality.

Data from 15,807 patients were collected through a retrospective cohort study. Self-reported morbidity and mortality reports of patients who had undergone neurological surgery (2007-2014) in the University of Michigan Health System were assessed and 785 complications were identified.

In the study, researchers found that there was an increased risk of complications (>50%) for the surgical procedures which were conducted between 9 pm and 7 am. This also increased complications, particularly in later periods. The type of surgery, emergency operation or an elective surgery predicted the severity of the complication.

The outcomes from the task which was accomplished outside the "normal" timeframe (i.e. after-hours or on the weekend) were statistically worse.

The average age of the patient population varied with the surgical day. Higher age groups had surgical start times earlier in the day, and lower ages later in the day. The variation in other patient factors was unlikely to be clinically significant. The emergency cases predominated while the percentage of elective cases decreased in the later day.

The authors acknowledge that while the after-hour effect is a potential explanation for the increased odds of complications with later surgical start times, there could be other explanations.

Aditya Pandey mentioned, “We need to continue to study this relationship as we aim to minimize surgery-related complications. Could it mean that health systems need to invest more with respect to increasing the number of surgical teams and operating rooms to allow for a greater proportion of surgeries to be performed during day hours and that urgent cases should be stabilized and performed during day hours? These are important questions that must be raised as we continue to solidify the relationship between the surgical start time and surgical complications.”