Associations between worsening renal function and 30-day outcomes among Medicare beneficiaries hospitalized with heart failure.

Background: Kidney disease is common among patients with heart failure, but relationships between worsening renal function (WRF) and outcomes after hospitalization for heart failure are poorly understood, especially among patients with preserved systolic function. We examined associations between WRF and 30-day readmission, mortality, and costs among Medicare beneficiaries hospitalized with heart failure.

Methods: We linked data from a clinical heart failure registry to Medicare inpatient claims for patients >or=65 years old hospitalized with heart failure. We defined WRF as a change in serum creatinine >or=0.3 mg/dL from admission to discharge. Main outcome measures were readmission and mortality at 30 days after hospitalization and total inpatient costs.

Results: Among 20,063 patients hospitalized with heart failure, WRF was common (17.8%) and more likely among patients with higher baseline comorbidity and more impaired renal function. In unadjusted analyses, WRF was associated with similar subsequent mean inpatient costs (USD 3,255 vs USD 3,277, P = .2) but higher readmission (21.8% vs 20.6%, P = .01) and mortality (10.0% vs 7.2%, P < .001). The differences persisted after adjustment for baseline patient and hospital characteristics (hazard of readmission 1.10 [95% CI 1.02-1.18], hazard of mortality 1.53 [95% CI 1.34-1.75]). Associations of WRF with readmission and mortality were similar between patients with reduced and preserved systolic function.

Conclusions: Worsening renal function during hospitalization for heart failure is an independent predictor of early readmission and mortality in patients with reduced and preserved systolic function.