Newborn and childhood screening programmes: criteria, evidence, and current policy.

creening is offered to apparently well individuals to identify those at high risk of a specific condition, for whom early treatment, more effective treatment, or information may be offered in order to improve health outcome or to provide opportunities for informed decision making. By definition, screening tests are not diagnostic tests and therefore cannot separate reliably those with a specific condition from those without. Hence, those with a negative screening result will include some affected individuals , usually referred to as " false negatives " , who may be falsely reassured by the screening result. Conversely, those with a positive screening result will include unaffected individuals, usually referred to as " false positives " , who may be worried unnecessarily or be exposed to the risks of subsequent diagnostic tests. Therefore the threshold for a positive test will be determined by balancing the goals of screening and the perceived disbenefits of missing affected individuals or falsely labelling healthy individuals. 2 In the past screening tests have often been introduced as a result of the enthusiasm of one or more individuals without evidence of effectiveness or careful consideration of the wider implications of false reassurance or false labelling. In the UK, this has led to the refinement of the historic " Wilson and Jungner " criteria, 3 so that all proposed screening programmes are assessed against specified criteria. To introduce a more systematic approach , the National Screening Committee (NSC) was established in 1996 with the remit that it should advise the Minister of State for Health on screening issues. Even though there are now separate health administrations, the NSC still has a role across the whole of the UK. One of the first tasks of the NSC was to define criteria for an acceptable screening programme. In recognition that the whole programme and not just the screening test has to be acceptable, there are now 19 criteria, although all may not have to be met for each programme. They cover the condition, the test, the treatment , and broader aspects of the programme. 4 These criteria provide a framework for appraising evidence in relation to current or proposed screening programmes, which in turn form the basis of policy recommendations. For a current programme, these may include recommendations to continue screening, perhaps with modifications, or to discontinue the programme. For a proposed programme, these may include advice either to implement, or …