Medical screening

In medicine, screening is a strategy used to test for as-yet-unrecognised conditions or risk markers in individuals or populations without symptoms or signs of the disease being screened. Screening interventions are designed to identify conditions which could at some future point turn into disease, thus enabling earlier intervention and management in the hope to reduce mortality and suffering from a disease. Although screening may lead to an earlier diagnosis, not all screening tests have been shown to benefit the person being screened- overdiagnosis, misdiagnosis, and creating a false sense of security are some potential adverse effects of screening. Additionally, some screening tests can be inappropriately overused. For these reasons, a test used in a screening program, especially for a disease with low incidence, must have good sensitivity in addition to acceptable specificity. Several types of screening exist: universal (population-based) screening involves testing of all individuals in a certain category (for example, all children of a certain age). Case finding involves testing a smaller group of people based on the presence of risk factors (for example, because a family member has been diagnosed with a hereditary disease). When delivered to large numbers of people at the population level rather than by individual clinicians, testing asymptomatic people for disease because they have one or more risk factors is sometimes referred to as targeted or stratified screening. Screening interventions are not designed to be diagnostic, and often have significant rates of both false positive and false negative results. In the US, frequently updated recommendations for screening are provided by the independent panel of experts, the United States Preventive Services Task Force. In the UK, recommendations are provided by the UK National Screening Committee.