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

AIM: To assess the practical feasibility of the Paranoid-Depressivity Scale (PD-S, Paranoid-Depresivitäts-Skala), the Frankfurt Self-feeling Scale (FBS, Frankfurter Befindlichkeitsskala), and two visual analogy scales of: sense of illness (WAC) and self-feeling (WAS).

METHOD: 210 patients with schizophrenia of various clinical courses. All patients in the study group were required to complete each scale twice, at 48 hr intervals. For statistical analysis, two sets of data were singled out (1) the relationship between refusal/inability to complete the scale repeatedly and the selected clinical variables; (2) observations made by the doctor, while the patient was completing the scales.

RESULTS

Statistical analysis revealed, that clinical factors like restlessness, autism, maladaptation, recurrence/remission and lower educational status imply a significantly lower readiness of the patient towards completion of self-rating scales. The visual analogy scales were those more readily--and easily--completed by the patients; their interpretation, however, is difficult. Given this, the authors of this paper decided to shorten the questionnaire scales, which reducing the whole to aspects of vital diagnostic relevance. Whether this operation would influence the scales' diagnostic value, required ex-post analysis, which was subsequently performed. Summary analysis revealed that the application of the shortening of the PD-S and FBS had no significant impact on these scales' reliability and validity indices; furthermore, it resulted in a significant decline in the number of ambiguities and thus improved the comprehensiveness of the questionnaire's structure. Also, a significant increase in concordance between the self-rating results and the clinicians' diagnoses was observed.

CONCLUSIONS

Visual analogy scales are the more readily and easily applied in practice; a comprehensive interpretation is, however, virtually impossible. On the other hand, the PD-S and FBS are the more difficult for the patients to complete, due to their length, but their interpretation does not constitute a major problem. Ex-post analysis reveals, that shortening the complex questionnaires to their core aspects does not affect their psychometric value negatively; in fact--the contrary. The latter statement, however, requires verification in prospective studies.