Risk score may aid emergency heart failure decisions

Jun 12 2012

By Eleanor McDermid

A novel risk score may help physicians decide whether to admit or discharge patients who present to the emergency department (ED) with an acute episode of heart failure (HF), say its developers.

Douglas Lee (University of Toronto, Ontario, Canada) and colleagues constructed the score using data for 12,591 HF patients who presented to EDs in Ontario, Canada. This contrasts with previous studies that considered only hospitalized patients, they say.

"If a model is intended to guide hospitalization-versus-discharge decisions based on acute prognosis, it is important to examine a patient sample whose inception is presentation to the ED and not only those who were hospitalized," they write in the Annals of Internal Medicine.

The score, which the team calls the Emergency Heart Failure Mortality Risk Grade (EHMRG), was about 80% accurate for discriminating between patients who survived and those who died, in both the derivation and validation cohorts, compared with accuracies ranging from 53% to 75% for previously published algorithms based purely on hospitalized patients.

The EHMRG is based on 10 variables that predicted mortality among the 7433 patients in the derivation cohort. These are age, arrival by emergency medical services transport, systolic blood pressure, heart rate, oxygen saturation, levels of creatinine, potassium, and troponin, and whether patients have cancer or are taking metolazone.

Lee et al comment that the impact of the EHMRG depends on an institution's tendency to hospitalize HF patients.

"At institutions with higher rates of hospitalization of low-risk patients, use of the score may identify patients who can be safely discharged with appropriate postdischarge care," they say. "At EDs with higher baseline rates of discharge, the EHMRG may identify high-risk patients who may have been otherwise discharged and might benefit from rapid diagnostic testing and therapy provided in the acute hospital setting."

Seven-day mortality rates rose from about 0.3% for patients in EHMRG categories 1 and 2 (up to -15.9 points) to 8.5% for those in EHMRG category 5b (≥89.4 points). Each 20-point increase in EHMRG score raised the odds for death within 7 days by 41% in the derivation cohort and by 39% among the 5158 patients in the validation cohort.

The researchers note that the score should be used in conjunction with clinical judgment. "Symptomatic improvement, ability of the patient to seek follow-up care, and social circumstances should also be considered, along with quantification of acute prognosis," they say.

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