Dyspnea Due to Heart Failure (Without Chronic Respiratory Disease)
Positive Findings (Patient Has This)
| Risk Factors | Increased Disease Probability (Positive Likelihood Ratio) |
|---|---|
| History of Heart Failure | |
| History of Myocardial infarction | |
| History of Coronary artery disease | 1.8× (1.1-2.8) |
| History of Dyslipidemia | 1.7× (0.43-6.9) |
| History of Diabetes mellitus | 1.7× (1.0-2.7) |
| History of Hypertension | 1.4× (1.1-1.7) |
| History of Smoking | 0.84× (0.58-1.2) |
| History of COPD | 0.81× (0.60-1.1) |
| Symptoms | Increased Disease Probability (Positive Likelihood Ratio) |
|---|---|
| Paroxysmal nocturnal dyspnea | |
| Orthopnea | |
| Edema | |
| Dyspnea on exertion | 1.3× (1.2-1.4) |
| Fatigue and weight gain | 1.0× (0.74-1.4) |
| Cough | 0.93× (0.70-1.2) |
| Signs | Increased Disease Probability (Positive Likelihood Ratio) |
|---|---|
| 3rd heart sound (ventricullar filling gallop) | |
| Abdominojugular reflux | |
| JVD | |
| Rales | |
| Any murmur | |
| Lower extremity edema | |
| Valsalva maneuver | |
| SBP <100 mmHg | |
| 4th heart sound (atrial gallop) | 1.6× (0.47-5.5) |
| SBP >= 150 mmHg | 1.0× (0.69-1.6) |
| Wheezing | 0.52× (0.04-2.9) |
| Other | Increased Disease Probability (Positive Likelihood Ratio) |
|---|---|
| Clinician's Gestalt |
| CXR Findings | Increased Disease Probability (Positive Likelihood Ratio) |
|---|---|
| Pulmonary venous congestion | |
| Interstitial edema | |
| Alveolar edema | |
| Cardiomegaly | |
| Pleural effusion(s) | |
| Any edema | |
| Pneumonia | 0.50× (0.29-0.87) |
| Hyperinflation | 0.38× (0.20-0.69) |
| EKG Findings | Increased Disease Probability (Positive Likelihood Ratio) |
|---|---|
| Atrial fibrillation | |
| New T-wave changes | |
| Any abnormal finding | |
| ST elevation | 1.8× (0.80-4.0) |
| ST depression | 1.7× (0.97-2.9) |
| BNP Levels | Increased Disease Probability (Positive Likelihood Ratio) |
|---|---|
| ≥250 | |
| ≥200 | |
| ≥150 | |
| Clinical judgement or BNP ≥100 pg/ml | |
| ≥100 | |
| ≥50 | 1.7× (1.2-2.6) |
Negative Findings (Patient Doesn't Have This)
| Risk Factors | Decreased Disease Probability (Negative Likelihood Ratio) |
|---|---|
| History of Heart Failure | |
| History of Myocardial infarction | 0.69× (0.58-0.82) |
| History of Coronary artery disease | 0.68× (0.48-0.96) |
| History of Hypertension | 0.71× (0.55-0.93) |
| History of Dyslipidemia | 0.89× (0.69-1.1) |
| History of Diabetes mellitus | 0.86× (0.73-1.0) |
| History of Smoking | 1.4× (0.58-3.6) |
| History of COPD | 1.1× (0.95-1.4) |
| Symptoms | Decreased Disease Probability (Negative Likelihood Ratio) |
|---|---|
| Dyspnea on exertion | |
| Edema | 0.64× (0.39-1.1) |
| Orthopnea | 0.65× (0.45-0.92) |
| Paroxysmal nocturnal dyspnea | 0.70× (0.54-0.91) |
| Fatigue and weight gain | 0.99× (0.85-1.1) |
| Cough | 1.0× (0.87-1.3) |
| Signs | Decreased Disease Probability (Negative Likelihood Ratio) |
|---|---|
| Valsalva maneuver | |
| Rales | 0.51× (0.37-0.70) |
| Lower extremity edema | 0.64× (0.47-0.87) |
| JVD | 0.66× (0.57-0.77) |
| Abdominojugular reflux | 0.79× (0.62-1.0) |
| Any murmur | 0.81× (0.73-0.90) |
| 3rd heart sound (ventricullar filling gallop) | 0.88× (0.83-0.94) |
| SBP <100 mmHg | 0.97× (0.91-1.0) |
| 4th heart sound (atrial gallop) | 0.98× (0.93-1.0) |
| SBP ≥ 150 mmHg | 0.99× (0.84-1.2) |
| Ascities | 1.0× (0.99-1.1) |
| Wheezing | 1.3× (1.1-1.7) |
| Other | Decreased Disease Probability (Negative Likelihood Ratio) |
|---|---|
| Clinician's Gestalt |
| CXR Findings | Decreased Disease Probability (Negative Likelihood Ratio) |
|---|---|
| Cardiomegaly | |
| Any edema | |
| Pulmonary venous congestion | |
| Interstitial edema | 0.68× (0.54-0.85) |
| Pleural effusion(s) | 0.81× (0.77-0.85) |
| Alveolar edema | 0.95× (0.93-0.97) |
| Pneumonia | 1.0× (1.0-1.1) |
| Hyperinflation | 1.1× (1.0-1.1) |
| EKG Findings | Decreased Disease Probability (Negative Likelihood Ratio) |
|---|---|
| Any abnormal finding | 0.64× (0.47-0.88) |
| Atrial fibrillation | 0.79× (0.65-0.96) |
| New T-wave changes | 0.83× 0.74-0.92) |
| ST elevation | 0.98× (0.94-1.0) |
| ST depression | 0.95× (0.90-1.0) |
| BNP Levels | Decreased Disease Probability (Negative Likelihood Ratio) |
|---|---|
| ≥50 | |
| ≥80 | |
| Clinical judgement or BNP ≥100 pg/ml | |
| ≥100 | |
| ≥200 | |
| ≥250 | |
| ≥150 |
Narrative
Published/Updated
What are Likelihood Ratios?
LR, pretest probability and posttest (or posterior) probability are daunting terms that describe simple concepts that we all intuitively understand.
Let's start with pretest probability: that's just a fancy term for my initial impression, before we perform whatever test it is that we're going to use.
For example, a patient with prior stents comes in sweating and clutching his chest in agony, I have a pretty high suspicion that he's having an MI – let's say, 60%. That is my pretest probability.
He immediately gets an ECG (known here as the "test") showing an obvious STEMI.
Now, I know there are some STEMI mimics, so I'm not quite 100%, but based on my experience I'm 99.5% sure that he's having an MI right now. This is my posttest probability - the new impression I have that the patient has the disease after we did our test.
And likelihood ration? That's just the name for the statistical tool that converted the pretest probability to the posttest probability - it's just a mathematical description of the strength of that test.
Using an online calculator, that means the LR+ that got me from 60% to 99.5% is 145, which is about as high an LR you can get (and the actual LR for an emergency physician who thinks an ECG shows an obvious STEMI).
(Thank you to Seth Trueger, MD for this explanation!)