Original Article Emergency readmissions are substantially determined by acute illness severity and chronic debilitating illness: A single centre cohort study Richard Conway, Declan Byrne, Deirdre O'Riordan, Bernard Silke ⁎ Department of Internal Medicine, St. James's Hospital, Dublin 8, Ireland abstract article info Article history: Received 3 October 2014 Received in revised form 12 December 2014 Accepted 26 December 2014 Available online 10 January 2015 Keywords: Readmission Prediction Emergency medical admissions Background: The factors influencing hospital readmissions are debated. We assessed whether readmissions could be predicted using routinely collected hospital data. Methods: All emergency admissions to a single institution over 12 years (2002–2013) were included. The predictor variables, of acute illness severity, Manchester Triage Category, chronic disabling disease and Charlson co-morbidity scores, were studied univariably and entered into a multivariable logistic regression model to predict the bivariate of any readmission or none. A zero truncated Poisson regression model assessed the predictors against the readmission count and incidence rate ratios were calculated. Factors reflecting the clinical load on the emergency department were examined. Results: 66,933 admissions were recorded in 36,271 patients. The readmission rates at 1, 3, 6 and 9 years were 29.5%, 38.9%, 42.9% and 44.1%. Early readmissions represented 14.1%. In the multivariable model, an admission in the previous 6 months was the strongest predictor of readmission, OR of 5.02 (95% CI: 4.86, 5.18). Acute illness severity — OR of 2.68 (95% CI: 2.33, 3.09) for group VI vs group I, and chronic disabling score — OR of 2.08 (95% CI: 1.87, 2.32) for a score of 4+ vs 0 were significant predictors of readmission in the multivariable model. Both of these predictors demonstrated a linear relationship. Illness severity was the strongest predictor of an early readmission within 4 weeks. Conclusion: Readmissions increase as a function of time; illness severity, chronic disabling disease score and a recent admission are the strongest predictors of readmission. © 2014 European Federation of Internal Medicine. Published by Elsevier B.V. All rights reserved. 1. Introduction There is a rising trend of unplanned hospital medical readmissions; a particular concern are those occurring early — defined as within 1 month of hospital discharge; it has been suggested to adopt this time interval in comparative studies [1]. This trend of increase in readmissions is of concern because of implications about quality of care during index hospitalisations, but also because of the burden placed on the provision of acute hospital services [1,2]. It has been esti- mated that 13% of inpatients in the United States use more than half of all hospital resources through repeated admissions [3,4]. Reported rates of unplanned emergency readmissions in the United Kingdom and Ireland vary depending on the population and setting studied. Reported rates are 15.1% at 28 days from North East Thames [5], 28% at three months in Edinburgh [6], 38% at six months in London [7] and 19.5% at one year in Galway [8]. Overall, it has been estimated that 7% of hospital discharges result in a readmission [9], the number of these readmissions which are deemed avoidable varies widely between studies from 5% to 58.6% [10]. There have been conflicting results on the causes of hospital readmissions in the literature. A meta-analysis of 16 studies [11] showed that the risk of early readmission (within 31 days) was in- creased by 55% when care was of relatively low quality. A systematic review by Ashton et al. indicated that on average, sub-standard care increased the risk of early readmission by 24% [12]. However, DesHarnais et al. ranked 300 hospitals on 3 risk adjusted indices of hospital quality: mortality, readmissions and complications [13]. They found no relationship between a hospital's ranking on any one of these indices and it's ranking on the other two indices. These discrepancies may reflect methodological differences arising from the evaluation of direct clinical care in the first instances and organisational characteristics in the DesHarnais study. Several prediction models for readmission have been developed to identify specific patient characteristics that may be amenable to intervention. Many factors have been identified, such as advancing age, prior hospitalisation, male gender, co-morbidities, functional status, and economic disadvantage [2,14,15]. However many prediction models are complex and use information not currently routinely European Journal of Internal Medicine 26 (2015) 12–17 ⁎ Corresponding author. Tel.: +353 1 416 2777; fax: +353 1 410 3451. E-mail address: bernardsilke@physicians.ie (B. Silke). http://dx.doi.org/10.1016/j.ejim.2014.12.013 0953-6205/© 2014 European Federation of Internal Medicine. Published by Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect European Journal of Internal Medicine journal homepage: www.elsevier.com/locate/ejim