[Clinical use of diagnostic tests (Part 1): Analysis of the properties of a diagnostic test].

Diagnostic tests are widely used in clinical practice. Qualitative analysis of diagnostic test properties (validity, reproducibility and safety) has been systematized using clinical epidemiology tools that have introduced a series of concepts such as sensitivity, specificity and predictive values. Based on data reported by a clinical investigation, the present article illustrates the theoretical background underlying these concepts, explains the methodology for their calculation, and analyzes their main strengths and limitations. A second article (Part 2: Clinical application and usefulness of a diagnostic test), describes the manner in which information provided by a test should be applied in order to correctly resolve a clinical dilemma.