Question

A major health insurance company is considering nationwide implementation of a test using biomarkers to screen for colon cancer. The test is delivered in health clinics in two similar regions of the country, with the following results:

	Region A	Region B
Sensitivity	73%	84%
Specificity	86%	97%

What is the most likely cause of the difference in the test’s sensitivity and specificity between the two regions?

	a.	The test was not administered in similar conditions in the two regions
	b.	The prevalence of disease is different between the two regions
	c.	Length-biased sampling has occurred.
	d.	The test is detecting the disease earlier in its natural history in one of the regions.

Answer 1

only correct answer is option A

We know that sensitivity and specificity between the two regions, when applied on similar patients with similar settings or conditions, will result in equal sensitivity and specificity between the two region. If there is any difference in sensitivity and specificity between the two regions, then the possible difference must be due to the testing process error due to dissimilar conditions.

option B is incorrect because prevalence wil not be different between two regions to cause the difference in sensitivity and specificity between the two regions.

option C is incorrect because length biased sampling is not a possible error to cause the diference

option D is also incorrect because earlier detection is not valid reason for difference in sensitivity and specificity between the two regions