What drives day surgery rates in Austrian acute care hospitals? An analysis of variability at hospital level Regional disparities in outpatient MRI utilization in Austria: a Blinder-Oaxaca decomposition Regionale Variation in der österreichischen Gesundheitsversorgung

Hospitals are a key health care provider, accounting for nearly two-fifth of all health expenditure in the European Union. They therefore also play a central role in policy considerations to improve the efficiency of health care systems. One initiative being pursued in many countries is a stronger focus on patient outcomes instead of inputs. Large amounts of routinely collected data are used increasingly to measure and compare the quality of care in hospitals. The aim is to detect problems and weaknesses in the health care system and to identify options for reform. A main challenge when comparing hospitals is patient selection. Widely used risk adjustment methods rely on observable characteristics to account for patient selection, but are often criticized for their inability to fully control for differences in patients across hospitals. We assess hospital performance using exogenous variation shaped by the institutional setting of inpatient care in Upper Austria. Hospitals have agreed on a rotating schedule, where on every day, one or two hospitals are primarily responsible for the admission of inpatients. For patients in need of acute care, this schedule creates a quasi-random allocation into different hospitals. We use this variation in an instrumental variable (IV) framework to estimate hospital performance, and compare the results to traditional risk adjustment methods. We use patient mortality and readmissions as quality indicators and draw on administrative data from Upper Austria with hospital visits from the years 2005 to 2017. We find substantial differences between IV and risk adjustment estimates, and show that increasing the number of variables used to control for patient differences often does not provide more credible results. Parallel Session 1a: Hospital performance _____________________________________________________________________________________________ 7 Title: Frontier efficiency studies and quality: a review Authors: Margit Sommersguter-Reichmann 1 University of Graz