Abstract 275: Effects of Index Admission Length of Stay on Readmission Interval in Patients With Heart Failure
Authors: Breen Thomas J , Patel Hiren , Purga Scott , Fein Steven A , Philbin Edward F , Torosoff Mikhail 
Published: July 2021

Background:
Numerous quality improvement studies have attempted to identify variables that are predictive of repeat hospitalization in patients admitted with heart failure. The relationship between the length of hospital stay (LOS) during the index admission and the readmission risk in patients with heart failure has not been well investigated. Longer index LOS is likely in patients with multiple co-morbidities, which may also predict early readmission.

Methods:
The study included 720 patients with multiple admissions for heart failure to a single academic medical center between 2007-2016. Patients were stratified into four quartiles based on their LOS (days) during their initial admission. Demographic and clinical data were collected from charts.

Results:
The interquartile range of index admission LOS was 7 days. LOS of 1-7 days was observed in 439 patients (60.9%), 8-13 days in 175 (24.3%), 14-20 days in 58 (8.1%), and ≥21 days in 48 patients (6.7%). The longest re-admission interval of 553.5 (SD +/- 611) days was noted in patients with index admission LOS of 8-13 days, while the shortest re-admission interval of 329.1 (SD +/- 430.9) days was noted in patients with index admission LOS of ≥21 days (p=0.02). In comparison to patients with index admission LOS of 8-13 days, those admitted for 1-7 days had a readmission interval of 465.1 (SD +/- 630) days (p=0.11) and those admitted for 14-20 days lasted 444.7 (SD +/- 691.6) days (p=0.25). There were no significant differences in age, gender, race, tobacco use, or evidence-based medical treatment among the four groups. Insulin-dependent diabetes mellitus (IDDM) was more common in patients with increased index admission LOS of 14-20 days and ≥21 days (44.5% [26 of 58] and 47.9% [23 of 48], respectively), as compared to patients with LOS 1-7 days and 8-13 days (33.0% [145 of 439] and 28.6% [50 of 175], respectively, p=0.02). Similarly, chronic kidney disease (CKD) was more common in patients with LOS 14-20 days and ≥21 days (50% [29 of 58] and 56.3% [27 of 48], respectively). When adjusted for IDDM and CKD, the longest re-admission interval was still noted in patients with index admission LOS of 8-13 days, while the shortest re-admission interval was noted in patients with index admission LOS of ≥21 days (p=0.027).

Conclusion:
In our patients admitted with heart failure, 8 to 13-day index admission was associated with the longest readmission interval. It is possible that shorter index admission may not allow for sufficient medical optimization. This conclusion requires further study. While patients with prolonged index admission are more likely to have IDDM and CKD, these co-morbidities do not appear to result in shorter readmission intervals. There may be additional, currently not well investigated factors affecting readmission interval. Further research is needed to define optimal LOS and discharge criteria in patients admitted with a diagnosis of heart failure.