Modeling The Diagnostic Process And The Establishment Of Standardized Diagnostic Criteria

Diagnostic criteria are usually based on traditional teaching that may be influenced through time by the literature. The literature often reflects an informal distillation of diagnostic concepts held by clinical experts in the field. However, a few examples exist where an ad hoc declaration of diagnostic criteria for a condition have been widely accepted. For instance, the Jones criteria for the diagnosis of rheumatic fever, although revised intermittently (6), have been the accepted standard for the identification of this disease entity for more than 50 years (7). Other examples include the criteria used for the diagnosis of essential hypertension (8) and systemic lupus erythematosus (9,10).

The durability of the diagnostic criteria for these conditions suggests that there is a consensus as to their usefulness, although no formal means of obtaining agreement among the users of the criteria was used during their development. A widely accepted methodology for the establishment of diagnostic criteria in conditions lacking an accepted gold standard criterion has not been developed (8,11-13).

An exception to this has been the Diagnostic and Statistical Manual of Mental Disorders (DSM), currently in its fourth edition (14), which drew heavily on the use of expert panels during its development. The diagnostic criteria in the DSM-IV were established originally under the sponsorship of a national academic organization, the American Psychiatric Association. Committees of the American Psychiatric Association were created, comprising members from the research and clinical communities, including subspecialty interests. The panels functioned as consensus groups with the objective of establishing diagnostic criteria for psychiatric disorders within a framework of optimizing clinical usefulness, reliability, and compatibility with the International Statistical Classification of Diseases and Related Health Problems. Given the unique nature of mental disease, most of these diagnostic criteria have been based primarily on clinical judgment. Revisions of earlier drafts of the DSM have resulted from extensive field-testing and the process of refining the diagnostic criteria is an ongoing process. The DSM has become the reference standard for the labeling of psychiatric conditions.

The methodology used for the DSM represents a useful model for the development of diagnostic criteria that should be used more widely in clinical medicine. The key elements to its success appear to have been (1) the sponsorship of a well-respected national organization, (2) the use of a broadly based pool of credible experts functioning within the methodology of a group process, (3) a focus on clinical judgment, and (4) a continual process of field-testing and revision. Wherever feasible, the task of establishing diagnostic criteria should use this framework within the standard methodology for the creation of measurement scales. In other words, experts should be used in the process of item generation, item reduction, and validation. The focus should be on establishing consensus, using the various types of group process. In general, a more meaningful consensus will be likely if there is an avoidance of a geographic bias and all clinical groups that normally evaluate the condition participate in developing the criteria.

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