title: Conceptual issues for screening in the genomic era - time for an update?
abstract: 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 inasymptomaticindividuals and, second, they are generallyofferedto 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.
authors.affiliation: Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge UK.
authors.forename: Caroline F
authors.initials: CF
authors.lastname: Wright
authors.affiliation: PHG Foundation, Cambridge UK.
authors.forename: Ron L
authors.initials: RL
authors.lastname: Zimmern
keywords: clinical tests; genomic era; screening tests