Factors associated with unplanned readmissions in a major Australian health service

Objective: The aim of the present study was to gain an understanding of the factors associated with unplanned hospital readmission within 28 days of acute care discharge from a major Australian health service. Methods: A retrospective study of 20 575 acute care discharges from 1 August to 31 December 2015 was conducted using administrative databases. Patient, index admission and readmission characteristics were evaluated for their association with unplanned readmission in ≤28 days. Results: The unplanned readmission rate was 7.4% (n = 1528) and 11.1% of readmitted patients were returned within 1 day. The factors associated with increased risk of unplanned readmission in ≤28 days for all patients were age ≥65 years (odds ratio (OR) 1.3), emergency index admission (OR 1.6), Charlson comorbidity index >1 (OR 1.1-1.9), the presence of chronic disease (OR 1.4) or complications (OR 1.8) during the index admission, index admission length of stay (LOS) >2 days (OR 1.4-1.8), hospital admission(s) (OR 1.7-10.86) or emergency department (ED) attendance(s) (OR 1.8-5.2) in the 6 months preceding the index admission and health service site (OR 1.2-1.6). However, the factors associated with increased risk of unplanned readmission ≤28 days changed with each patient group (adult medical, adult surgical, obstetric and paediatric). Conclusions: There were specific patient and index admission characteristics associated with increased risk of unplanned readmission in ≤28 days however, these characteristics varied between patient groups, highlighting the need for tailored interventions. What is known about the topic?: Unplanned hospital readmissions within 28 days of hospital discharge are considered an indicator of quality and safety of health care. What does this paper add?: The factors associated with increased risk of unplanned readmission in ≤28 days varied between patient groups, so a 'one size fits all approach' to reducing unplanned readmissions may not be effective. Older adult medical patients had the highest rate of unplanned readmissions and those with Charlson comorbidity index ≥4, an index admission LOS >2 days, left against advice and hospital admission(s) or ED attendance(s) in the 6 months preceding index admission and discharge from larger sites within the health service were at highest risk of unplanned readmission. What are the implications for practitioners?: One in seven discharges resulted in an unplanned readmission in ≤28 days and one in 10 unplanned readmissions occurred within 1 day of discharge. Although some patient and hospital characteristics were associated with increased risk of unplanned readmission in ≤28 days, statistical modelling shows there are other factors affecting the risk of readmission that remain unknown and need further investigation. Future work related to preventing unplanned readmissions in ≤28 days should consider inclusion of health professional, system and social factors in risk assessments.