Measures to Evaluate a Screening Test

For ADC examination, both prelims and practical viva voce, and NEET MDS,  the various measures of evaluating a screening test must be known to the students.

There are various measures to evaluate a screening test that are as follows:

  1. Sensitivity
  2. Specificity
  3. Positive predictive value
  4. Negative predictive value

Sensitivity: Sensitivity is defined as the ability of a test to identify correctly all those who have the disease i.e. “true positive”.

Specificity: Specificity is the ability of a test to identify correctly those who do not have the disease i.e. “true negatives” 

Predictive value: Besides sensitivity and specificity, the performance of a screening test is measured by its “predictive value”. The predictive value tells us about the diagnostic power of the test. The predictive value of a positive test indicates the probability a patient with a positive test result has , in fact, the disease in question. As the prevalence of a disease in a given population increases, the accuracy of the predictive value of a positive test increases.

Yield: Yield is the amount of the previously unrecognized disease that is diagnosed as a result of the screening efforts.