There is a wide range of screening procedures. These range from self- or clinical exams to tests performed with special equipment and medical technologies. The effectiveness of screening procedures to correctly identify and classify individuals as having or not having a given disease rests heavily on two aspects of the test used to screen for a specific disease:
- A screening procedure’s sensitivity refers to its ability to designate an individual with disease as positive. A highly sensitive screening procedure means that there are few false negative results. That is that individuals that have the disease are identified as not having the disease.
- A screening procedure’s specificity refers to its ability to designate an individual who does not have a disease as negative. A screening procedure with high specificity means that there are few false positive results. That is that individuals that do not have the disease are identified as having the disease.
Together, sensitivity and specificity impact a screening procedure’s predictive value. Positive predictive value is the probability that a patient with a positive (abnormal) test result actually has the disease. Negative predictive value is the probability that a person with a negative (normal) test result is truly free from disease.
Innovations in screening procedures are yielding improvements in predictive value at the earliest stages of disease while being less invasive and more cost-effective when compared to previous testing procedures.