What is the clinical evidence from this study?

Study design: Cohort. Population: Acute heart failure (n=610). Intervention: High risk group (BUN >27.5 mg/dl and age >86 years) vs. Low risk group (BUN ≤27.5 mg/dl). Primary outcome: 1-year mortality (HR 2.0, 95% CI 1.7-2.4, p=<0.001).

September 26, 2011Open Access

Risk stratification for 1-year mortality in acute heart failure

Q: What are the key findings of this study?

A simple risk stratification algorithm using blood urea nitrogen and age identified acute heart failure patients at high risk for 1-year mortality, with a hazard ratio of 2.0 compared to low-risk patients.

CHCorinna HeinischSpitalzentrum Centre hospitalier Biel- Bienne CTChristopher TschungUniversity Hospital of Basel MPMihael PotockiJohns Hopkins University

Key Result

A simple risk stratification algorithm using blood urea nitrogen and age identified acute heart failure patients at high risk for 1-year mortality, with a hazard ratio of 2.0 compared to low-risk patients.

Study Design

Type

Cohort (n=610)

Multicenter

Structured PICO

Population

610 consecutive patients presenting to the emergency department with acute heart failure (AHF), median age 82, 46% female, based in Switzerland. Excluded: cardiogenic shock or end-stage kidney disease.

Intervention

Risk stratification using classification and regression tree (CART) analysis based on blood urea nitrogen (BUN) and age

Outcome

1-year mortality (death within 360 days)hard clinical

A simple risk stratification algorithm using blood urea nitrogen and age can effectively identify acute heart failure patients at high risk for 1-year mortality.

Main Result

Effect estimate: HR 2.0 (95% CI 1.7-2.4)

Absolute Event Rate: 63% vs 22%

p-value: p=<0.001

Limitations

AHF is a clinical diagnosis and no gold standard exists, leading to possible misclassification.
Assessed all-cause mortality because classification of cause of death can be difficult and unreliable.
Data derived from a single-center study requires external validation in larger multicenter studies.
Patients with terminal kidney failure requiring dialysis were excluded from the analysis.

Abstract

BACKGROUND: Simple tools for risk stratification of patients with acute heart failure (AHF) are an unmet clinical need, particularly regarding long-term mortality. METHODS: We prospectively enrolled 610 consecutive patients presenting to the emergency department with AHF. The diagnosis of AHF was adjudicated by two independent cardiologists. The classification and regression tree (CART) analysis was used to develop a simple risk algorithm. This was internally validated by cross-validation. RESULTS: One-year follow-up was complete in all patients (100%). A total of 201 patients (33%) died within 360 days. The CART analysis identified blood urea nitrogen (BUN) and age as the best single predictors of 1-year mortality and patients were categorised to three risk groups: high risk group (BUN >27.5 mg/dl and age >86 years), intermediate risk group (BUN >27.5 mg/dl and age ≤ 86 years) and low risk group (BUN ≤ 27.5 mg/dl). The Kaplan-Meier curves showed a significant increase in mortality in the high risk group compared with the lower risk groups (log-rank test p <0.001). The hazard ratio regarding 1-year mortality between patients identified as low and high risk was 2.0 (95% confidence interval, 1.7-2.4), with statistically significant differences between all risk groups (p <0.001). The likelihood-based 95%-confidence set for the age- and the urea-threshold is contained in the rectangular set defined by 25 mg/dl ≤ urea threshold ≤30.6 mg/dl and 76 years ≤ age threshold ≤96 years. CONCLUSION: These results suggest that AHF patients at low, intermediate and high risk for death within 360 days can be easily identified using patient's demographics and laboratory data obtained at presentation. Application of this simple risk stratification algorithm may help to improve the management of these patients.

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