Vol 1 n° 3 - Nosology and Nosography
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The term “nosological classification” is often used in connection with medical classification systems, and the tendency is to equate it with “diagnosis” and “validity.” However, particularly in the case of psychi- atry, this is far from always being the case. From a sci- entific point of view, the two most up-to-date classifi- cation  systems  in  use  today—the  Diagnostic  and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV), and the International Classification of Dis- eases, 10th Revision  (ICD-10)—may be considered as the theoretical basis of current psychiatric nosology. In this paper we show that the instrumentally gener- ated  DSM-IV or ICD-10 diagnoses of schizophrenia have relatively low validity in comparison with clini- cian expert diagnoses. If medical classification is to be realistic, simple to use, and reliable, nosological sys- tems must be based not only on established facts, but also on theoretical assumptions regarding the nature of disease. ince  their  official  introduction, the  Interna- tional Classification of Diseases, 10th Revision (ICD- 10),1 and the Diagnostic and Statistical Manual of Men- tal Disorders, Fourth Edition  (DSM-IV),2  operational classification systems have largely become an integral part of the body of knowledge of psychiatrists through- out the world and instruments  they constantly refer to. In this article I look at some of the questions that have been raised in connection with these classifications, both as a result of the growing number of critical analyses and of my own experience. This short contribution does not claim to provide exhaustive answers, but merely to stimulate further discussion. Psychiatrists probably all started adopting operational diagnostic classification systems, such as the ICD and DSM classifications, on the assumption that the relia- bility of the diagnoses therein defined was unequivo- cally demonstrated to be very high across the centers and even countries of evaluation, without realizing that the general consensus was based on the lowest level of validity conceivable, since it resulted from the mutual agreement of experts rather than on any proven facts concerning the etiology of mental disorders.This means that in the absence of biological markers for most psy- chopathological  disorders,  diagnostic  features  were based on clinical descriptions, resulting in “official” noso- logical groupings. One of the main objections raised by clinical psychiatrists was that in many instances diag- noses were based on the numbers of certain symptoms.3 Nevertheless, in spite of initial warnings of oversimplifi- cation, the two most widely used official classifications— DSM and ICD—came to be largely regarded as noso- logically valid by medical doctors, official institutions, and even the public at large.The interesting, but logical, paradox is that those least satisfied with these so uni- versally acclaimed classifications are probably the psy- chiatrists. In this article, I would like to briefly discuss two frequently asked questions: (i) what is the validity of the current diagnostic process? and (ii) what are the weak points of the DSM and ICD classifications? C l i n i c a l   r e s e a r c h Keywords: validity; nosology; DSM-IV; ICD-10; schizophrenia; psychopathology Author affiliations: Postgraduate Medical Institute, Charles University, Prague, Czech Republic 1 8 5 Validity of nosological classification Petr  Smolik, MD, PhD Address for correspondence: Prof P. Smolik, Department of Psychiatry IPVZ, Ustavni 91, 181 02 Praha 8, Czech Republic
(e-mail: psmolik@ms.anet.cz) S