You are reading a case report in International Journal of Rheumatic Diseases.
A 58-year-old man presented with persisting pain in his right shoulder following a fall from the stairs one month before. The attending rheumatologist performed a clinical examination which led her to suspect a subscapularis tendon rupture. To confirm the suspicion, she ordered an ultrasound examination. You know that the sensitivity of ultrasound for assessment of a rupture of the subscapularis tendon is 89-100%.
The correct answer is In 0-11% of all patients who have a rupture, ultrasound will miss it.
Sensitivity of a test is the ability of a test to detect a disease when it is present.
Sensitivity = (number of true positives) / (number of true positives + number of false negatives)
By Dr George Bruyn, Director, Reumakliniek Lelystad, the Netherlands
You are reading an experiment on a new blood test for rheumatoid arthritis.
To assess whether a new blood test is suitable for screening on rheumatoid arthritis, the Health Authority assesses the test on 1000 volunteers. In addition, an MRI of all these volunteers is conducted to check for synovitis. The blood test yields positive results in 50 persons, whereas the gold standard MRI indicates normal in 45 of these. Twenty persons with a negative blood test demonstrate a positive MRI.
The correct answer is Sensitivity is 0.20; specificity is 0.95
Specificity of a test is the ability of a test to correctly reject healthy patients without a condition.
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