NBME 17 Additional testing to confirm the diagnosis of TA (NBME Answers)

NBME 17 Answers ↦

nbme17/Block 1/Question#1 (28.0 difficulty score)
An 80-year-old woman is being evaluated for ...
Additional testing to confirm the diagnosis of TA🔍,📺
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+5
submitted by kstebbins(14),

I was thrown off because Pathoma/Dr. Sattar and pixorize say it is critical to start steroids ASAP to avoid permanent damage to the ophthalmic artery and blindness in patients suspected of having Giant Cell (Temporal) Arteritis.

This means not waiting for diagnostic confirmation.

However a 99% sensitivity does not equate to a 99% certainty of GCA/TA. So additional testing is the best answer choice even though her elevated ESR gives us strong suspicion of GCA/TA.

nsinghey exactly, the reason why its not steroids is because that answer choice says the diagnosis of TA has been established with 99% certainty which is NOT true +2

j44n this question threw me because you tx this on clinical suspicion alone. So i was torn between the right answer and the fact that if you repeated ESR again and its positive you youd the give steroids +5

+2
submitted by cheesetouch(192),

Sensitivity of 99% means that almost all TA will have high ESR. (Sn = tp/(tp+fn) -> low False negative). HOWEVER, a specificity of just 60% means high ESR can indicate MANY OTHER disease processes. In a test with low specificity, more tests should be done to confirm diagnosis.