ABSTRACT
Screening is performed to identify whether people have a disease for which they currently have no symptoms.
The concept of screening is discussed in this Chapter with specific reference to the UK National Screening Committee’s criteria for appraising the viability, effectiveness and appropriateness of a screening programme.
Issues around evaluating the accuracy of screening tests are also discussed, including sensitivity, specificity, positive predictive value, negative predictive value and prevalence of diseased subjects in the screened population. Data for an example screening programme are used to calculate these measures; step by step instructions for the calculations involved are provided as well as the interpretation of each measure and the overall usefulness of the screening test itself.
