Readmission-free period and in-hospital mortality at the time of first readmission in acute heart failure patients-NRD-based analysis of 40,000 heart failure readmissions

The 30-day readmission rates, predictors, and outcomes for acute heart failure (AHF) patients are well published, but data beyond 30 days and the association between readmission-free period (RFP) and in-hospital readmission-related mortality remain unknown. We queried the National Readmission Database to analyze comparative outcomes of AHF. Patients were divided into three groups based on their RFP: group 1 (1-30 days), group 2 (31-90 days), and group 3 (91-275 days). AHF cases and clinical variables were identified using ICD-9 codes. The primary outcome was in-hospital mortality at the time of readmission. A total of 39,237 unplanned readmissions occurred within 275 days; 15,181 within group 1, 11,925 within group 2, and 12,131 within group 3. In-hospital mortality in groups 1, 2, and 3 were 7.4%, 5.1%, and 4.1% (p < 0.001). Group 1 had higher percentages of patients with cardiogenic shock (1.3% vs. 0.9% vs. 0.9%; p < 0.001), acute kidney injury (30.2% vs. 25.9% vs. 24.0%; p < 0.001), dialysis use (8.6% vs. 7.5% vs. 6.9%; p < 0.001), and non-ST elevation myocardial infarction (4.4% vs. 3.8% vs. 3.6%; p < 0.001), but there was no statistical difference among the three groups for ST-elevation myocardial infarction, percutaneous coronary intervention (PCI), or ventricular assist device use at the time of index admission. However, group 3 had higher PCI (1.7%) compared with groups 1 and 2 (p < 0.001). In multivariable logistic regression, groups 2 and 3 had odd ratio of 0.70 and 0.55, respectively, for in-hospital mortality compared with group 1. Longer RFP is associated with decreased risk of in-hospital mortality at the time of first readmission.