Conceptual issues for screening in the genomic era - time for an update?

BACKGROUND: Screening tests are ubiquitous in modern medicine; however a consensus view on the criteria that distinguish screening from clinical testing remains strangely elusive. although numerous definitions of screening have been suggested, there is considerable variation amongst them, leading to confusion and disagreement amongst clinicians and public health professionals alike. In light of developments in genomics, the question of what screening entails is becoming increasingly pressing.
METHODS: We evaluated the concepts underlying definitions of screening versus clinical testing and investigated their ethical implications.
RESULTS: We suggest that just two key concepts underlie screening: first, screening tests are performed in asymptomatic individuals and, second, they are generally offered to individuals who otherwise believe themselves to be healthy (with respect to the disease being screened for). all the other characteristics commonly invoked to describe screening - including the systematic use of rapid tests for risk stratification within a particular population - can be better categorised as either practical requirements or by-products of screening programmes rather than screening tests.
CONCLUSIONS: We emphasise the need to differentiate between opportunistic screening and clinical testing because of the differing prior probability of disease and thus the differing ethical burden of responsibility placed upon the physician in each scenario. Physicians need to appreciate the shifting moral burden placed upon them in relation to reactive clinical testing versus proactive screening, and the different legal obligations that may ensue.