A new test for diabetes was carried out of the 80 people who were tested positive (+ve), it was found that actually 40 had diabetes and out of 9920 people who were tested negative (-ve) only 9840 did not have the disease actually. The sensitivity of this new test is:
The sensitivity of this new test for diabetes is 33%. The question has a increased number of true negatives (9840 people) and a increased number of false positives (40 people). It has more value to rule out diabetes but with a less sensitivity the test has less diagnostic value. A 33% sensitive means 33 per cent of the diseased people screened by the test will give a "true positive" result and the remaining 67 per cent will give a "false negative" result. In the above question: Total no of people who took the test 1000 No of true positives 40 No of false positives 40 No of true negatives 9840 No of false negatives 80 Sensitivity 33% Specificity 99.5% Predictive value of a positive test 50% Predictive value of a negative test 99% Ref: Park's Textbook of Preventive and Social Medicine, 19th Edition, Pages 118-119.
33%
50%
65%
99%