SCREENING AND EARLY DETECTION IN TRANSFUS ION - WHEN ARE THEY INDICATED

Screening is proposed to allow an early intervention concerning a dise ased individual, but its public health consequences are seldom conside red. We propose criteria to judge whether a screening program can be a ssociated to a benefit to patients or society. These criteria refer to the magnitude of disease, the characteristics of the pre-clinical sta ge, the availability of reliable and valid tests, the effectiveness an d risk for all individuals, whether they are diseased or not, and acce ptability to the health-care system and to individuals. We illustrate the application of these criteria to screening of human immunodeficien cy virus among blood donors, hepatitis among recipients of labile bloo d products, and bacterial contaminations among febrile recipients. The se criteria should be considered in decision analyses including altern atives to screening and all aspects of safety regarding patients and p opulation.