Time-of-Day Effects on Surgical Outcomes in the Private Sector: A Retrospective Cohort Study
Received 8 April 2009; received in revised form 11 May 2009; accepted 12 May 2009. published online 24 July 2009.
Background
Surgical care is delivered around the clock. Elective cases within the Veterans Affairs health system starting after 4 pm appear to have an elevated risk of morbidity, but not mortality, compared with earlier cases. The relationship between operation start time and patient outcomes is not described in private-sector patients or for emergency cases.
Study Design
We performed a retrospective cohort study of 56,920 general and vascular surgical procedures performed from October 2001 through September 2004, and entered into the National Surgical Quality Improvement Program database. Operation start time was the independent variable of interest. Random effects, hierarchical logistic regression models adjusted for patient, operative, and facility characteristics. Two independent models determined associations between start time and morbidity or mortality. Subset analysis was performed for emergency and nonemergency cases.
Results
After adjustment for patient and procedure characteristics, mortality had a moderately strong association with start time, but only for nonemergency cases starting 9:30 pm to 7:30 am (odds ratio = 1.752; p = 0.028; reference 7:30 am to 9:30 am). As for morbidity, after adjustment, operations starting 9:30 am to 1:30 pm and 5:30 pm to 9:30 pm were associated with a weakly elevated risk of morbidity, but those starting 9:30 pm to 7:30 am demonstrated a strong effect on morbidity (odds ratio = 1.32; p < 0.0001). Subgroup analysis showed this effect was largely a result of elevated risk of morbidity in emergency cases from this overnight time period (odds ratio = 1.48; p = 0.001).
Conclusions
Surgical start times are associated with risk-adjusted patient outcomes. In terms of facility operations management and resource allocation, consideration should be given to the capacity to accommodate cases with differences in risk during different time periods.
aDepartment of Surgery, Philadelphia VA Medical Center, Philadelphia, PA
bDepartment of Surgery, School of Medicine, University of Pennsylvania, Philadelphia, PA
cDepartment of Surgery, School of Medicine, Washington University in St Louis, St Louis, MO
dHealth Outcomes Program, University of Colorado, Denver, CO
eOlin Business School, Washington University in St Louis, St Louis, MO
fDepartment of Surgery, John Cochran Veterans Affairs Medical Center, St Louis, MO
gCenter for Health Policy, Washington University in St Louis, St Louis, MO
Correspondence address: Rachel R Kelz, MD, MSCE, FACS, Department of Surgery, University of Pennsylvania School of Medicine, 3400 Spruce St, 4 Silverstein, Philadelphia, PA 19104
Disclosure Information: Nothing to disclose.
This study does not represent the views of the ACS or the ACS NSQIP.
This material is based upon work supported by the Office of Research and Development, competitive pilot project fund, Department of Veterans Affairs 693/11. Dr Hall was supported by the Center for Health Policy under the direction of Dr William Peck, Washington University in St Louis, St Louis, MO. This article is partially derived from the Patient Safety in Surgery Study, and partially supported by the Agency for Healthcare Research and Quality, grant number 5U18HS011913, entitled “Reporting System to Improve Patient Safety in Surgery.”
ABSTRACT