Abstract
Background: The Standard for Clinicians’ Interview in Psychiatry (SCIP) is a new valid and reliable diagnostic interview with dimensional output (1–2). The psychosis module of the SCIP has 18 symptoms and signs representing the core symptoms and signs of schizophrenia (delusions, hallucinations, and disorganized thoughts). The total psychosis score (TPS) is measured by the sum of the hallucinations, delusions, and disorganization dimensions. There is a lack of consensus on how to define the remission, response, and exacerbation of schizophrenia and schizoaffective disorders and there is an urgent need to assess the response to antipsychotic medications using a dimensional model.
Methods: To measure the remission, response, and exacerbation of schizophrenia and schizoaffective disorders, the Remission and Exacerbation Criteria (REC) is defined as the percent change in the total psychosis score (TPS) between a baseline assessment and a subsequent assessment. Compared to the baseline assessment, the REC at a subsequent assessment can be categorized as one of the following 7 categories: (1) Remission (full resolution): 100% decrease in symptoms (TPS = 0), (2) Substantial response: ≥75% decrease in TPS, (3) Good response: 50%–74% decrease in TPS, (4) Partial response: 25%–49% decrease in TPS, (5) Subthreshold response: >0 to <25% decrease in TPS, (6) Unchanged: no change in TPS from the baseline score, and (7) Exacerbation: increase in TPS from baseline score. To study the reliability of the TPS and REC categories, 41 patients from 2 inpatient psychiatric units who had been diagnosed with schizophrenia or schizoaffective disorders (mean age = 36, 49% male, 92% White, 68% with high school education or greater) were interviewed by 2 raters at the same time (inter-rater reliability). Patients were interviewed by 2 raters upon admission and before discharge from the inpatient psychiatric units. Inter-rater reliability of the TPS and kappa for REC were calculated.
Results: Inter-rater reliability for the patients’ total psychosis score (TPS) was good, r = 0.95. Inter-rater reliability for the REC categories of remission, response, and exacerbation using the 25 percentile increments was fair (kappa = 0.56).
Conclusion: The SCIP is the only instrument in the psychiatric literature that has a reliable method of assessing remission, response, and exacerbation in schizophrenia and schizoaffective disorders.