What was the true positive count in the carotid duplex study when testing for >60% stenosis?

The count for true positives in the carotid duplex study specifically indicates the number of patients accurately diagnosed with greater than 60% stenosis. A true positive occurs when the test correctly identifies an individual with the condition in question — in this case, the significant narrowing of the carotid arteries.

B is the correct choice because it reflects the number of cases where the carotid duplex study successfully identified subjects who indeed had over 60% stenosis according to the reference standard. In clinical studies, such accurate identification of patients with severe stenosis is essential because these individuals often require closer monitoring or more aggressive intervention to prevent adverse events like strokes.

This value of 53 suggests that the test is effective in detecting significant stenosis in a population, supporting the reliability of carotid duplex as a diagnostic tool in vascular technology.