METHODS AND RESULTS -The BIOSTAT‐CHF index cohort included 2516 patients with new or worsening HF symptoms: 1694 enrolled as inpatients (acute HF) and 822 as outpatients (worsening HF in chronic outpatients). A validation cohort included 935 inpatients and 803 outpatients. Multivariable models were developed in the index cohort using clinical characteristics, routine laboratory values, and proteomics data to examine which factors predict adverse outcomes in both conditions and to determine which factors differ between acute HF and worsening HF in chronic outpatients, validated in the validation cohort.

Patients with acute HF had substantially higher morbidity and mortality (6 months mortality was 12..3% for acute HF and 4..7% for worsening HF in chronic outpatients). Multivariable models predicting 180‐day mortality and 180‐day HF re‐admission differed substantially between acute HF and worsening HF in chronic outpatients. CA‐125 was the strongest single biomarker to distinguish acute HF from worsening HF in chronic outpatients, but only yielded a C‐index of 0..71. A model including multiple biomarkers and clinical variables achieved a high degree of discrimination with a C‐index of 0..913 in the index cohort and 0..901 in the validation cohort.

CONCLUSION - The study identifies different characteristics and predictors of outcome in acute HF patients as compared to outpatients with chronic HF developing worsening HF. The markers identified may be useful in better diagnosing acute HF and may become targets for treatment development.