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1002: Hospital variation in the rate of emergency department visits after ambulatory stone surgery

C. Dauw, Ann Arbor (US)
Dauw C., Hollingsworth J., Dupree J., Hou H., Ghani K.
University of Michigan, Dept. of Urology, Ann Arbor, United States of America, 0
33rd Annual EAU Congress (EAU18)
Date – time - Location
19 March 2018, 14:00 - 15:30, Green Area, Room 1 (Level 0)
Poster Session 73 - Safe access through natural orifice: It is the era of ureteroscopy
Stones: Ureteroscopy

Introduction & Objectives

Emergency department (ED) visits after ambulatory surgery for urinary stone disease are significant events for patients and the healthcare system. To inform quality improvement (QI) efforts at reducing these visits, we assessed variability in ED visits following ambulatory stone surgery as well as patient and hospital factors associated with their occurrences.

Materials & Methods

The Michigan Value Collaborative (MVC) is a QI initiative whose goal is to enhance the quality and efficiency of healthcare delivery in the State. MVC collects complete inpatient and outpatient medical claims from residents enrolled in Medicare fee-for-service or Blue Cross Blue Shield of Michigan’s preferred provider organization insurance plans. Using these data, we identified patients who underwent shockwave lithotripsy (SWL) or ureteroscopy (URS) at hospitals in the state of Michigan between 2012 and 2015. We identified patients who required an ED visit within 30 days of surgery and calculated individual hospital ED visit rates. We fitted multilevel models to quantify variation across hospitals and associations between ED visits and patient, provider, and hospital characteristics.


We identified a total of 15,657 procedures (6,696 SWL and 8,961 URS) that were performed at 58 participating hospitals during the study period. The mean adjusted rate of ED visit after ambulatory stone surgery was 17.0%. This rate was stable over time (P=0.47). When analyzed individually, SWL and URS were associated with a 14.9% and 18.5% ED visit rate, respectively. ED visit rates after URS were higher, with variation in rates across hospitals (range 3% to 26% for SWL; 11% to 43% for URS; figure). Younger patients, females, those with more comorbidities, and those in urban settings more commonly presented to the ED after ambulatory stone surgery (all P<0.05).


Wide variation exists in ED visit rates after SWL or URS in Michigan, and overall nearly 1 in 5 patients undergoing ambulatory stone surgery visit the ED. Further, our analysis identifies patient factors that can be used in the design of QI initiatives aimed at reducing these encounters.