Newswise — Winner of the Robert Florin Award, Michael Bohl, MD, presented his research, Overlapping Surgeries are not Associated with Worse Patient Outcomes: Retrospective Multivariate Analysis of 14,872 Neurosurgical Cases Performed at a Single Institution, during the 2017 American Association of Neurological Surgeons (AANS) Annual Scientific Meeting.

The purpose of this study was to characterize and evaluate the effect of overlapping surgery on patient outcomes. Study authors conducted a retrospective analysis of all neurosurgical procedures performed at a single institution from July 2013-May 2016. Case variables were extracted from the electronic medical record, including patient sex, age, type of procedure, resident year of training, evening case, emergency case, ASA score, severity of illness, risk of mortality and percentage of case overlap. The authors ran univariate and multivariate analyses for the following primary outcomes: procedure length, length of hospital stay, return to OR, disposition upon discharge, hospital readmission and mortality. Separate analyses were performed for overlap thresholds of 0 percent, 20 percent, 50 percent and 100 percent.

All of the 14,872 cases performed during the study period were included in the statistical analyses. Univariate analysis showed a benefit for overlapping cases in terms of hospital LOS, return to OR and disposition status. No difference was found for hospital readmission and mortality. Overlapping cases were significantly longer and were staffed by more senior residents. Multivariate analysis showed either no difference or a benefit for overlapping surgeries for all the measured outcomes except procedure length.

These results reject the hypothesis that overlapping surgeries are associated with worse outcomes. When considered in the context of the current debate regarding overlapping surgeries, these results argue against claims that overlapping surgeries are dangerous or harmful to patients. 


Author Block: Michael Mooney, MD; John Sheehy, MD; Abigail Cantwell; Steve Chang, MD; Kristina Chapple, PhD; Udaya Kakarla, MD; and Robert Spetzler, MD



Disclosure: The author reported no conflicts of interest.


Media Representatives: The 2017 AANS Annual Scientific Meeting press section will include releases on highlighted scientific research, AANS officers and award winners, Neurosurgery Awareness Month and other relevant information about the 2017 program. Releases will be posted under the “Media” area on the 2017 AANS Annual Scientific Meeting website. If you have interest in a topic related to neurosurgery or would like to interview a neurosurgeon — either onsite or via telephone — during the event, please contact Alice Kelsey, AANS associate executive director, via email at


About the 2017 AANS Annual Scientific Meeting: Attended by neurosurgeons, neurosurgical residents, medical students, neuroscience nurses, clinical specialists, physician assistants, allied health professionals and other medical professionals, the AANS Annual Scientific Meeting is the largest gathering of neurosurgeons in the nation, with an emphasis on the field’s latest research and technological advances. The scientific presentations accepted for the 2017 event will represent cutting-edge examples of the incredible developments taking place within the field of neurosurgery. Find additional information about the 2017 AANS Annual Scientific Meeting and the meeting program here.


Founded in 1931 as the Harvey Cushing Society, the American Association of Neurological Surgeons (AANS) is a scientific and educational association with more than 10,000 members worldwide. The AANS is dedicated to advancing the specialty of neurological surgery in order to provide the highest quality of neurosurgical care to the public. Fellows of the AANS are board-certified by the American Board of Neurological Surgery, the Royal College of Physicians and Surgeons of Canada or the Mexican Council of Neurological Surgery, A.C. Neurosurgery is the medical specialty concerned with the prevention, diagnosis, treatment and rehabilitation of disorders that affect the spinal column, spinal cord, brain, nervous system and peripheral nerves.


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