This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Social & Preventive Medicine
For the diagnosis of SLE, 6 tests are done of which 4 came as positive and 2 negative. For the confirmation the following must be known: 
Select and explain. 
A. Prior probability of having the disease, Sensitivity & specificity of each test, B. Incidence of SLE, predictive value of the tests, C. Incidence & prevalence of SLE, D. Relative risk of the patient
A: Prior probability of having the disease, Sensitivity & specificity of each test
Answer: A: Prior probability of having the disease, Sensitivity & specificity of each test 
Explanation: For the confirmation we need to know the amount of previously unrecognised disease that is diagnosed as a result of screening effo. It depends on sensitivity and specificity of the test, prevalence of the disease, paicipation of the individuals in the detecting programme. So in a test to diagnose SLE, there should be the previous probability and the sensitivity an specificity of tests. Ref: Park's Textbook of Preventive and Social Medicine, 21st Edition, Page 56