Designs for the evaluation of the endotoxin assay as a diagnostic test

The comprehensive evaluation of the usefulness of a new diagnostic test should include a hierarchy of assessments ranging from reliability and validity to impact on clinical decision making and outcome. This paper reviews some of the design methodology appropriate for evaluation of an endotoxin assay such as the Limulus Amebocyte Lysate test. Primary focus is on the design and analysis of studies aimed at establishing diagnostic validity. However, suggestions are made for the design of clinical studies of management change and to determine the impact on patient outcome. Results from such studies must be combined into a cost-utility calculation eventually to determine societal benefit.