Analysis of Worsening Heart Failure Events in an Integrated Health Care System

Background: There is growing interest to disentangle worsening heart failure (WHF) from location of care and move away from hospitalization as a surrogate for acuity.

Objectives: The purpose of this study was to describe the incidence of WHF events across the care continuum from ambulatory encounters to hospitalizations.

Methods: We studied calendar year cohorts of adults with diagnosed heart failure (HF) from 2010-2019 within a large, integrated health care delivery system. Electronic health record (EHR) data were accessed for outpatient encounters, emergency department (ED) visits/observation stays, and hospitalizations. WHF was defined as ≥1 symptom, ≥2 objective findings including ≥1 sign, and ≥1 change in HF-related therapy. Symptoms and signs were ascertained using natural language processing.

Results: We identified 103,138 eligible individuals with mean age 73.6 ± 13.7 years, 47.5% women, and mean left ventricular ejection fraction of 51.4% ± 13.7%. There were 1,136,750 unique encounters including 743,039 (65.4%) outpatient encounters, 224,670 (19.8%) ED visits/observation stays, and 169,041 (14.9%) hospitalizations. A total of 126,008 WHF episodes were identified, including 34,758 (27.6%) outpatient encounters, 28,301 (22.5%) ED visits/observation stays, and 62,949 (50.0%) hospitalizations. The annual incidence (events per 100 person-years) of WHF increased from 25 to 33 during the study period primarily caused by outpatient encounters (7 to 10) and ED visits/observation stays (4 to 7). The 30-day rate of hospitalizations for WHF ranged from 8.2% for outpatient encounters to 12.4% for hospitalizations.

Conclusions: ED visits/observation stays and outpatient encounters account for approximately one-half of WHF events, are driving the underlying growth in HF morbidity, and portend a poor short-term prognosis.