Why use it

Acute heart failure is one of the most common reasons for ED visits in adults over 65, accounting for over 1 million annual hospitalizations in the US alone. While most AHF patients are admitted, up to 20–30% may be safely managed with accelerated observation protocols or ED discharge. The OHFRS provides a structured, evidence-based tool to identify high-risk patients who require admission and, by exclusion, the low-risk group who might be candidates for safe early discharge. This avoids premature discharge while reducing unnecessary admissions.

About

The Ottawa Heart Failure Risk Scale (OHFRS) is a validated clinical decision rule developed by Stiell and colleagues at the Ottawa Hospital Research Institute and published in the European Heart Journal (2013). It was designed to identify emergency department (ED) patients presenting with acute heart failure (AHF) who are at high risk of serious adverse events within 30 days of ED presentation, thereby guiding safe admission vs. discharge decisions. The OHFRS evaluates 10 clinical variables derived from history, physical examination, and investigations available in the ED. Points are assigned for the presence of each variable, and a score ≥1 (any positive variable) identifies high-risk patients. The scale was derived in 559 patients and validated in 1,100 patients across multiple Canadian EDs. In the validation cohort, a score ≥1 had a sensitivity of 89.8% for 30-day serious adverse events (death, relapse requiring hospitalization, myocardial infarction, major intervention) with specificity of 47.6%. Patients scoring 0 had a 30-day event rate of approximately 2.8%.

When to use

All patients presenting to the ED with a primary diagnosis of acute decompensated heart failure
After initial ED resuscitation and treatment — OHFRS is applied once initial assessment is complete
Deciding admission vs. observation unit vs. discharge in treated AHF patients
NOT for patients with hemodynamic instability, acute MI, or STEMI — these require admission regardless of score
NOT validated in patients with de novo (first presentation) heart failure or cardiogenic shock

Formula

OHFRS = Presence of ANY of the following 10 variables: History: 1. Stroke or TIA history 2. Currently intubated prior to or at ED presentation (exclude — automatic admission) Vital Signs at Triage: 3. Heart rate ≥110 bpm 4. SpO₂ <90% on room air 5. Active chest pain at triage Findings / Investigations in ED: 6. Heart rate ≥110 bpm on ECG in ED 7. Urea ≥12 mmol/L (BUN ≥33.6 mg/dL) 8. Serum CO₂ <35 mEq/L (bicarbonate <35) 9. New ischemic changes on ECG 10. NT-proBNP ≥5000 pg/mL (if available) Score 0: Low risk (~2.8% 30-day adverse event rate) Score ≥1: High risk — admission recommended

Pearls & pitfalls

ANY positive criterion (score ≥1) constitutes a high-risk screen — unlike other scores, there is no additive point system. The scale functions as a checklist of independently important risk markers.
Stroke or TIA history is the variable most commonly underappreciated — it reflects the atherosclerotic and embolic burden that predicts cardiac events, not just neurological risk.
A heart rate ≥110 bpm at triage reflects inadequate rate control and sympathetic activation — both markers of severe decompensation.
SpO₂ <90% on room air at triage identifies patients with severe respiratory failure from pulmonary edema who need prompt inpatient management.
The OHFRS was derived and validated in the Canadian healthcare setting — most variables are universally applicable, but local admission practices and follow-up resources should be considered.
The OHFRS score of 0 (low-risk) should NOT be used as the sole basis for discharge — clinical judgment, treatment response (urine output after IV furosemide, dyspnea relief), and social circumstances must also be assessed.
Hyponatremia (Na <136 mEq/L) at triage is a powerful independent predictor of adverse outcomes in AHF and is one of the OHFRS criteria.
The OHFRS does not include BNP or NT-proBNP, LVEF, or creatinine — incorporating these lab values may further refine risk stratification beyond the score.

Next steps

Score 0 (Low Risk): 30-day serious adverse event rate approximately 2.8%. May be a candidate for observation protocol or early discharge after treatment response assessment. Ensure adequate response to initial ED diuresis, cardiology follow-up within 1–2 weeks, reliable home monitoring, and social support. Score ≥1 (High Risk): Hospital admission strongly recommended. Cardiology or internal medicine inpatient management. Optimize diuretic therapy, identify and treat precipitating cause. Echocardiography if not recent. Consider guideline-directed medical therapy (GDMT) optimization.

Evidence

Stiell IG et al. Prospective and explicit clinical validation of the Ottawa Heart Failure Risk Scale, with and without use of quantitative NT-proBNP. Acad Emerg Med. 2015;22(3):261-269. PMID:25716520. Original derivation: Eur Heart J. 2013. Validation cohort n=1,100: sensitivity 89.8%, specificity 47.6% for 30-day serious adverse events at score ≥1. Low-risk (score 0) had 2.8% 30-day event rate.

References

Stiell IG et al. Derivation of the Ottawa Heart Failure Risk Scale — a multi-centre prospective cohort study. Eur Heart J. 2013;34(19):1448-1456. — link
Stiell IG et al. Prospective and explicit clinical validation of the Ottawa Heart Failure Risk Scale, with and without use of quantitative NT-proBNP. Acad Emerg Med. 2015;22(3):261-269. — link
McDonagh TA et al. 2021 ESC Guidelines for the diagnosis and treatment of acute and chronic heart failure. Eur Heart J. 2021;42(36):3599-3726. — link

Ottawa Heart Failure Risk Scale (OHFRS)

Calculator