Abstract 19243: Using Inpatient Mortality Differential from Weekend Admission to Identify the Role of Hospital Structures: The Case of Ischemic Stroke
Background: Although hospitals vary widely in inpatient mortality (IM) from acute stroke, little is known about the influence of hospital structures, i.e., the setting in which care is delivered. We examine this using a unique study design (difference-in-difference estimation) based on exploiting the within-hospital variation in IM between weekday and weekend admissions, thereby attenuating confounding from unobserved differences across hospitals.
Methods: We merged discharge and American Hospital Association data for all hospitalizations for ischemic stroke (N=257,089) from all hospitals (N=407) from four states (AZ, FL, MA and NJ; 2004-08). We estimated a hierarchical logit IM prediction model, including interactions of weekend admission and hospital structure indicators. The odds ratio (OR) of each interaction (difference-in-difference estimate) compares the excess IM from weekend admission (“excess weekend IM”) for hospitals with a structure (say, bed capacity<200) with the excess weekend IM for hospitals without that structure.
Results: Average hospital IM was 4.7% with interquartile range of 1.0% to 8.9%. Weekend admissions accounted for 25% of all admissions. Average excess weekend IM was +7.5% with hospital interquartile range of -23% to +42%. We examined nine hospital structure indicators (see Table); three structures were associated with significant excess weekend IM - hospitals with a) <200 beds (+33%), b) 100+ daily census (+28%) and c) 200+ stroke volume (+18%). One-third of hospitals exhibited all three structures. Lower nurse staffing ratio and smaller ICU capacity were associated with sizable, but not significant, excess weekend IM. Other structures, including teaching status, safety-net, public ownership, were not associated with excess weekend IM.
Conclusion: Hospitals with lower bed capacity, higher daily census and higher stroke volume were associated with significant excess IM from weekend admission for ischemic stroke.
- © 2010 by American Heart Association, Inc.