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

Obstructive sleep apnea & Polycythemia: Mechanism

Obstructive sleep apnea (OSA) is thought to lead to secondary polycythemia due to intermittent hypoxia,…

8 months ago

Pale Stool, Dark Urine & Biliary Obstruction: Mechanism

Catabolism of hemoglobin leads to the release of heme, which converts to biliverdin and then…

8 months ago

Why is Tongue Scalloping seen with Obstructive Sleep Apnea?

Tongue scalloping refers to the series of indentations along the sides of the tongue that…

10 months ago

Older Age and Obstructive Sleep Apnea (OSA): Mechanism

Older age is recognized as a risk factor for obstructive sleep apnea.[1] But why? Suspected…

1 year ago

How does Weight Affect Obstructive Sleep Apnea (OSA): Mechanism

Being overweight (BMI ≥ 25 kg/m2)/Obese (BMI ≥ 30 kg/m2) is one of the most…

1 year ago

Nocturia and OSA: Mechanism

Nocturia is a common symptom associated with obstructive sleep apnea. [1] Img Cred: Am J…

2 years ago

This website uses cookies.