[Self-rating scales in schizophrenia: validity assessment of the Paranoid-Depression Scale (PD-S), the Frankfurt Self-feeling Scale (FBS) and of two visual analogy scales].

AIM

To assess the validity of the Paranoid-Depressivity Scale (PD-S, Paranoid-Depresivitäts-Skala), the Frankfurt Self-feeling Scale (FBS, Frankfurter Befindlichkeitsskala), and of two visual analogy scales: the Sense of Illness Scale (WAC) and the Self-feeling Scale (WAS).

METHOD

210 patients with schizophrenia of various clinical courses. Diagnostic validity was evaluated by comparing the results of self-rating with clinical assessment using the CGI, KOSS-C, BPRS, and KOSS-W scales. Content validity was evaluated by analysis of the results' correlation with given clinical and social-demographic variables. Theoretical (construct) validity was evaluated through factorial analysis with Varimax rotation of the principal elements.

RESULTS

The correlation between the self-rating scales and the clinical assessment scales was moderate in the case of questionnaire scales and low for the visual analogy scales. Scales of a similar type were found to correlate to a very high degree. Correlation with clinical assessment depended significantly on the phase and degree of disorder--it was lower in periods of exacerbation and higher during remission. The results of the complex questionnaire scales en somme, correlate better with symptoms considered as typical for schizophrenia, than with others, whereas the isolated self-rating constructs (paranoid, depressive) correlate well with the appropriate dimensions of clinical assessment. There was no significant correlation between the clinical symptoms and dimensions, and the results of self-rating using the two visual analogy scales. Factorial analysis revealed that the internal structure of the basic constructs of the questionnaire scales (general attitude, mood, self-feeling) was based on a very rational concept, as well as the fact that the factors isolated have a rational foundation within the theoretical and clinical picture of schizophrenic disorders.

CONCLUSIONS

The validity of self-rating scales remains a complex question; analysis of diagnostic, content and theoretical validity seems to confine this method to the role of a complementary, albeit interesting, diagnostic tool; the extent and importance of this role, however, is still to be investigated.