You have diagnosed a patient clinically as having SLE and ordered 6 tests. Out of which 4 tests have come positive and 2 are negative. To determine the probability of SLE at negative. To determine the probability of SLE at this point, you need to know-
Prior Probability of SLE; sensibility and specificity of each test
Incidence of SLE predictive value of each test
Incidence and prevalence of SLE
Relative risk of SLE in this patient
.sensitivity is the ability of a test to identify correctly those who actually have the disease,that is true positives.specificity is the ability of a test to identify correctly those who in actual do not have the disease.prior probability of disease such as SLE can be calculated by knowing these. ref:park&;s textbook,22 nd ed,pg 131
Screening