The backwoods of clinical and research assessment of psychosis

The aim of this thesis was to explore and improve methodology and utility of clinically applicable dimensional, staging and clinical profiling models for patients with psychotic and related disorders. This was approached at three levels: firstly, we evaluated the psychometric properties of the dimensional assessment of symptoms by the Clinician-Rated Dimensions of Psychosis Symptom Severity, and subsequently, determining the inter-rater reliability of the clinical staging model and profile characteristics. We evaluated inter-rater reliability with and without short training courses suitable for clinical practice (Part 1). Secondly, we evaluated the validity of the clinical staging model in schizophrenia spectrum disorders. We determined the construct and clinical validity of the staging model in ambulatory and clinically admitted patients. Furthermore, we assessed whether cognitive parameters are associated with higher clinical stages in a large sample of patients with psychotic disorders (Part 2). Thirdly, we evaluated the pre-training inter-rater reliability in clinical research. Moreover, we determined the proportion of reported inter-rater reliability coefficients and training procedures in double-blind randomized clinical trials with antipsychotic and antidepressant medication. Overall, we conclude that achieving sufficient inter-rater reliability of new diagnostic methods requires more attention, both in scientific research and in daily practice. This field of research can also be marked as the backwoods of clinical and research assessments — remote areas that could be neglected because of difficulties that may be encountered.