Impact of Hospital Population Case-Mix, Including Poverty, on Hospital All-Cause and Infection-Related 30-Day Readmission Rates

MAJOR ARTICLE Impact of Hospital Population Case-Mix, Including Poverty, on Hospital All-Cause and Infection-Related 30-Day Readmission Rates Shruti K. Gohil, 1,a Rupak Datta, 2,a Chenghua Cao, 1 Michael J. Phelan, 3 Vinh Nguyen, 3 Armaan A. Rowther, 1 and Susan S. Huang 1 Division of Infectious Diseases and Health Policy Research Institute, University of California Irvine School of Medicine, 2 Department of Medicine, Yale School of Medicine, and 3 Department of Statistics, University of California, Irvine Background. Reducing hospital readmissions, including preventable healthcare-associated infections, is a na- tional priority. The proportion of readmissions due to infections is not well-understood. Better understanding of hospital risk factors for readmissions and infection-related readmissions may help optimize interventions to prevent readmissions. Methods. Retrospective cohort study of California acute care hospitals and their patient populations discharged between 2009 and 2011. Demographics, comorbidities, and socioeconomic status were entered into a hierarchical generalized linear mixed model predicting all-cause and infection-related readmissions. Crude verses adjusted hos- pital rankings were compared using Cohen’s kappa. Results. We assessed 30-day readmission rates from 323 hospitals, accounting for 213 879 194 post-discharge person-days of follow-up. Infection-related readmissions represented 28% of all readmissions and were associated with discharging a high proportion of patients to skilled nursing facilities. Hospitals serving populations with high proportions of males, comorbidities, prolonged length of stay, and populations living in a federal poverty area, had higher all-cause and infection-related readmission rates. Academic hospitals had higher all-cause and infection- related readmission rates (odds ratio 1.24 and 1.15, respectively). When comparing adjusted vs crude hospital rank- ings for infection-related readmission rates, adjustment revealed 31% of hospitals changed performance category for infection-related readmissions. Conclusions. Infection-related readmissions accounted for nearly 30% of all-cause readmissions. High hospital infection-related readmissions were associated with serving a high proportion of patients with comorbidities, long lengths of stay, discharge to skilled nursing facility, and those living in federal poverty areas. Preventability of these infections needs to be assessed. Keywords. hospital infections; readmissions; healthcare associated infections; poverty. Hospital readmissions represent a major health and ﬁ- nancial burden to patients. Nearly 30% of hospitalized patients are readmitted within 1 year of hospitalization, with over half occurring within 30 days of discharge Received 27 August 2014; accepted 24 June 2015; electronically published 30 June 2015. a S. K. G. and R. D. contributed equally to this work. Correspondence: Shruti K. Gohil, MD, MPH, UCI Medical Center, Division of In- fectious Diseases, 333 City Blvd, W, Ste 400, Orange, CA 92697 (skgohil@uci.edu). Clinical Infectious Diseases ® 2015;61(8):1235–43 © The Author 2015. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com. DOI: 10.1093/cid/civ539 [1, 2]. The Centers for Medicare and Medicaid Services (CMS) estimate rehospitalization cost among Medicare patients alone at $17 billion annually. Readmission rates serve as hospital quality indicators in an era of transpar- ency, accountability, and best practices in healthcare de- livery [3]. As of October 2012, CMS began restricting reimbursements for readmissions associated with con- gestive heart failure, acute myocardial infarctions, and pneumonia and are now implementing further ﬁnancial restrictions for hospitals with elevated all-cause read- mission rates [4–6]. The interest in readmission rates is driven, in part, by the recognition that a signiﬁcant proportion of Hospital Readmissions Due to Infection CID 2015:61 (15 October)