Schizophrenia: comparison of 13 diagnostic systems in a cross-sectional study1

Abstract

SummaryThe concordance and degree of overlap between 13 diagnostic systems for schizophrenia, including the five European systems of Berner, Bleuler, Langfeldt, Pull and Schneider, were evaluated in a cross-sectional study (N = 51) taking the phase of illness (acute or residual) into account. The diagnostic assessments were processed by computer using a 183-item standardised checklist and a data-processing program in GW-Basic language. The inter-rater reliability, as assessed by Kappa coefficient, was good to excellent for each diagnostic system established by this method (K from 0.5 to 1). When comparing the concordance between pairs of 13 diagnostic systems for schizophrenia in acute and residual phase groups, results showed that only two significant relationships were not influenced by the phase of illness (Carpenter x RDC; Catego x Schneider), while 24 were. These included only two relationships in the acute group (Carpenter Catego; Carpenter Schneider) and 22 links between pairs of systems in the residual group. In the acute group, no diagnosis of schizophrenia, including duration criteria such as those of DSM III-R, Feighner, Langfeldt, Pull and RDC, was linked to other systems. In the residual group, the operational systems such as Catego, DSM III-R, Feighner, Newhaven, Pull and RDC had more than five relationships with the other systems whereas the non-operational systems of Bleuler, ICD9, Langfeldt and Schneider had less than four relationships with the others. Except Pull's criteria, the European diagnostic systems, in particular Berner's and Bleuler's, seemed to differ from the others because of the few relationships displayed. The results underline the importance of taking the phase of illness into account when comparing between studies utilizing different diagnostic systems for schizophrenia. They also show the relationships between European and international diagnostic systems, insufficiently established so far.