Categories: Other Tips

Likelihood Ratios

Likelihood Ratio Approximate Change in Probability (%)*
Values between 0 and 1 decrease the probability of disease  
 0.1 −45
 0.2 −30
 0.3 −25
 0.4 −20
 0.5 −15
1 0
Values greater than 1 increase the probability of disease  
 2 +15
 3 +20
 4 +25
 5 +30
 6 +35
 7  
 8 +40
 9  
 10 +45

 

Easy to recall at the bedside by simply remembering 3 specific LRs—2, 5, and 10—and the first 3 multiples of 15 (i.e., 15, 30, and 45).

An LR of 2 increases probability 15%, one of 5 increases it 30%, and one of 10 increases it 45%. For those LRs between 0 and 1, the clinician simply inverts 2, 5, and 10 (i.e., 1/2 = 0.5, 1/5 = 0.2, 1/10 = 0.1).

Just as the LR of 2.0 increases probability 15%, its inverse, 0.5, decreases probability 15%. Similarly, an LR of 0.2 (the inverse of 5) decreases probability 30%, and a LR of 0.1 (the inverse of 10) decreases it 45%.

Get Medical Pearls directly to your inbox every week!
Weekly posts with high yield medical knowledge, directly to your mailbox!
Dr. C Humphreys

Internal Medicine

Recent Posts

Mechanism of a Mixed Apnea

Mixed apneas are characterized by absent respiratory effort and airflow in the first section of…

12 months ago

How Does Hypothyroidism Cause Hypoventilation?

Although rare, the differential diagnosis of hypoventilation and hypercapnia respiratory failure includes hypothyroidism. It is…

12 months ago

Why is Pro-BNP/ BNP lower in Obesity?

B-type natriuretic peptide (BNP) is a hormone created in response to cardiac wall stretch due…

1 year ago

What is Peribronchovascular Distribution on CT imaging?

A common finding described on computed tomography (CT) imaging. A disease with a peribronchovascular distribution…

2 years ago

Trapped Lung vs. Lung Entrapment

Though often used synonymously; Trapped Lung and Lung Entrapment technically describe separate entities along the…

3 years ago

Cause of Pericardial Effusion in Pulmonary Hypertension: Pathogenesis

It is not clearly understood why patients with pulmonary hypertension (PH) develop pericardial effusions. However,…

3 years ago

This website uses cookies.