Volume 53 | Number 5 | October 2018

Abstract List

Hillary J. Mull Ph.D., Amy K. Rosen Ph.D., William J. O'Brien M.S., Nathalie McIntosh Ph.D., Aaron Legler M.P.H., Mary T. Hawn M.D., M.P.H., Kamal M. F. Itani M.D., Steven D. Pizer Ph.D.


To examine factors associated with 0‐ to 7‐day admission after outpatient surgery in high‐volume specialties: general surgery, orthopedics, urology, ear/nose/throat, and podiatry.

Study Design

We calculated rates and assessed diagnosis codes for 0‐ to 7‐day admission after outpatient surgery for Centers for Medicare and Medicaid Services () and Veterans Health Administration () dually enrolled patients age 65 and older. We also estimated separate multilevel logistic regression models to compare patient, procedure, and facility characteristics associated with postoperative admission.

Data Collection

2011–2013 surgical encounter data from the Corporate Data Warehouse; geographic data from the Area Health Resources File; enrollment and hospital admission data.

Principal Findings

Among 63,585 outpatient surgeries in 124 facilities, 0‐ to 7‐day admission rates ranged from 5 percent (podiatry) to 28 percent (urology); nearly 66 percent of the admissions occurred on the day of surgery. Only 97 admissions were detected in the data (1 percent). Surgical complications were diagnosed in 4 percent of admissions. Procedure complexity, measured by relative value units or anesthesia risk score, was associated with admission across all specialties.


As many as 20 percent of outpatient surgeries result in an admission. Complex procedures are more likely to be followed by admission, but more evidence is required to determine how many of these reflect potential safety or quality problems.