Validation of ratings on the six-item Positive and Negative Syndrome Scale obtained via the Simplified Negative and Positive Symptoms Interview among outpatients with schizophrenia

• Published in: Journal of psychopharmacology (Oxford) 2022-11, Vol.36 (11), p.1208-1217
• Main Authors: Nielsen, Cecilie Marie, Kølbæk, Pernille, Dines, David, Pedersen, Martin Locht, Danielsen, Andreas Aalkjær, Holmgård, Camilla, Wissing, Sanne, Esbøl, Anne-Mette, Fuglsang, Nina Friis Bak, Nguyen, Tuan Dang, Mors, Ole, Opler, Mark, Correll, Christoph U, Østergaard, Søren Dinesen
• Format: Article
• Language: English
• Subjects: Adult; Antipsychotics; Female; Humans; Male; Mental disorders; Outpatients; Psychiatric Status Rating Scales; Psychometrics; Ratings & rankings; Reproducibility of Results; Schizophrenia; Schizophrenia - diagnosis; Schizophrenic Psychology; Validity
• ISSN: 0269-8811; 1461-7285
• DOI: 10.1177/02698811221131992

Background: The six-item Positive and Negative Syndrome Scale (PANSS-6) is a measure of the severity of core symptoms of schizophrenia, which can be administered via the brief Simplified Negative and Positive Symptoms Interview (SNAPSI). A recent study has confirmed the validity of PANSS-6 ratings as derived by SNAPSI (PANSS-6SNAPSI) among inpatients with schizophrenia. Aims: We aimed to test the validity of PANSS-6SNAPSI among outpatients with schizophrenia using PANSS-6 ratings extracted from the 30-item PANSS-30 as derived by the Structured Clinical Interview for the Positive and Negative Syndrome Scale (PANSS-6SCI-PANSS) as a gold standard reference. Methods: PANSS-6SNAPSI and PANSS-6SCI-PANSS ratings were obtained at two time points by independent raters with established inter-rater reliability. Agreement between PANSS-6SNAPSI and PANSS-6SCI-PANSS ratings was estimated via intra-class coefficients (ICCs) and responsiveness over time was quantified using Spearman’s rank correlation coefficients. Post hoc “leave-one-out” analyses were carried out, in which each rater in turn was excluded from the ICC calculations. Results: Seventy-three outpatients with schizophrenia participated in the study (mean age: 38.3 years; 56% males). The ICC for PANSS-6SNAPSI versus PANSS-6SCI-PANSS was 0.67 [95%CI = 0.56–0.76] and the Spearman’s rank correlation coefficient for responsiveness was 0.40 (p = 0.004). When data from a specific outlying rater were excluded, the ICC for PANSS-6SNAPSI versus PANSS-6SCI-PANSS was 0.75 [95% CI = 0.63–0.83] and the Spearman’s rank correlation coefficient for responsiveness was 0.55 (p = 0.018). Conclusions: We found PANSS-6SNAPSI ratings to have acceptable clinical validity, suggesting that PANSS-6SNAPSI can be used for both inpatients and outpatients with schizophrenia.