[Nosologic criteria in rheumatology].

Nosologic criteria are important tools for diagnosis and categorization of rheumatic diseases, disease status and outcome. They have been developed predominantly for phenomenologic syndromes (of unknown etiology) and are standards of the scientific communication as well as necessary instruments for the selection of patient groups for investigations in different fields of rheumatology (epidemiology, etiology, pathogenesis, clinical rheumatology, diagnostics, therapy). Diagnostic criteria help to identify disease in individual patients. Classification criteria separate patients with a particular disease from patients without the disease and are useful to select and describe patient groups. Status indices assess disease activity and actual damage according to reversible or irreversible features respectively. Prognostic criteria differentiate patients with probably favorable or severe disease course or outcome, and outcome criteria are designed to assess the overall impact of a disease as dependent variables for clinical studies. This review describes the different types and purposes of nosological criteria in different rheumatic diseases as well as their problems. Some aspects of the actually used criteria especially from the "Diagnostic and Therapeutic Criteria Committee" of the American College of Rheumatology are critically commented.