The Classification of Mental Disorders in Primary Care: A Guide through a Difficult Terrain

Abstract

Background: Primary care physicians traditionally have a strong interest in the mental health of their patients. Three classification systems are available for them to diagnose, label, and classify mental disorders: 1) The ICD-10 approach with three options, 2) The DSM-IV approach with two options, and 3) the ICPC approach with two options. This article lists important similarities and differences between the systems to help potential users choose the option that best meets their needs. Methods: Definitions for depressive disorder, anxiety disorder, and somatization disorder are compared on five characteristics of classification: 1. the domain, 2. the scope, 3. the nature of the definitions, 4. focus on episodes of care, and 5. clinical guidelines. Results: Primary care physicians and psychiatrists have different perspectives, reflected in different classifications. Each system has specific possibilities and limitations with regard to the diagnosis of mental disorders. For common mental disorders it is possible, however, to choose codes from one system while maintaining compatibility with the other two. Comparability as to the diagnostic content of the different classes, however, is more difficult to establish. The available classification systems give both primary care physicians and psychiatrists options to diagnose, label, and to classify mental disorders from their own perspective, but once a system has been chosen the clinical comparability of a patient with the same diagnosis in other systems is limited. Conclusion: Compatibility among systems can be optimized by strictly following a number of rules. The conversion between ICPC and ICD-10 (and consequently DSM-IV) allows simultaneous use of ICPC and ICD-10 as a classification and DSM-IV as the standard nomenclature. This is of particular interest for computer based patient records in primary care. The clinical comparability of the same diagnosis in different systems however is limited by the characteristics of the different system.