Screening for the early detection of disease, the need for evidence.

BACKGROUND: Screening for the early detection of disease has had a spotted history. Structured approaches to the process of gathering and evaluating evidence, with the emphasis on well-controlled randomized studies, have greatly improved the beneficial potential of appropriate and effective screening. Good quality evidence will contribute to quality health care. ISSUES: The volunteer participants in screening programs must give fully informed consent. This means that they must be presented with clear and accurate statements of the advantages and disadvantages of the screening program. Among the screening programs that have been conducted include hyperhomocysteinemia and coronary artery disease, Down's syndrome, Neonatal Group B streptococcal disease, Type 2 diabetes mellitus and endometrial cancer. The evidence in these studies has strengths and weaknesses as to how they support or oppose a particular intervention. The laboratory has a major role to play in establishing and validating standards of accuracy for diagnostic tests. Agreement on standards and their application does not mean the end of different interpretation and controversy.
CONCLUSIONS: Laboratory physicians and scientists will be very effective consultants if they have the best available, high quality evidence for the appropriate use of laboratory tests.