LR+ values categories—which range corresponds to strong evidence to rule in disease?

LR+ values categories—which range corresponds to strong evidence to rule in disease?

• A. Greater than 5 and up to 10 indicates strong evidence.
• B. 5-10 indicates moderate evidence.
• C. 2-5 indicates small evidence.
• D. > 10: strong (rules in)

Answer: (D)

The main idea here is how a positive likelihood ratio (LR+) changes the probability that a patient has the disease. LR+ tells you how much a positive test result increases the odds of disease. When LR+ is greater than 10, that increase is large enough to be considered strong evidence to rule in the disease in most clinical situations. Think of it this way: a positive test with LR+ > 10 multiplies the pre-test odds by more than ten, producing a high post-test probability. For example, if your pre-test probability is around 20%, the pre-test odds are about 0.25. Multiplying by an LR+ of 10 gives post-test odds of 2.5, which corresponds to a post-test probability of about 71%. That level of certainty is typically enough to confirm the disease in many cases. Other ranges are less convincing for ruling in disease. An LR+ between 5 and 10 provides moderate evidence, while 2 to 5 gives small evidence, and values below 2 are not very informative for ruling in. So the value range that represents strong evidence to rule in disease is the one that exceeds 10.

The main idea here is how a positive likelihood ratio (LR+) changes the probability that a patient has the disease. LR+ tells you how much a positive test result increases the odds of disease. When LR+ is greater than 10, that increase is large enough to be considered strong evidence to rule in the disease in most clinical situations.

Think of it this way: a positive test with LR+ > 10 multiplies the pre-test odds by more than ten, producing a high post-test probability. For example, if your pre-test probability is around 20%, the pre-test odds are about 0.25. Multiplying by an LR+ of 10 gives post-test odds of 2.5, which corresponds to a post-test probability of about 71%. That level of certainty is typically enough to confirm the disease in many cases.

Other ranges are less convincing for ruling in disease. An LR+ between 5 and 10 provides moderate evidence, while 2 to 5 gives small evidence, and values below 2 are not very informative for ruling in. So the value range that represents strong evidence to rule in disease is the one that exceeds 10.