Research Article
Luba Leontieva*, [Jackie Dimmo
Abstract
Background: The Positive and Negative Syndrome Scale (PANSS) is a widely used instrument for symptom severity assessment in schizophrenia. Its Abstract Thinking item (N5) was developed for the assessment of thought disorder. This item currently lacks examples of correct and incorrect responses to similarities and proverb items. Different raters may judge these items as correct or incorrect based on their own level of abstraction, cultural background, and familiarity with possible responses. Precision in scoring is especially important, when the instrument is used to evaluate changes in schizophrenia symptoms over time and with treatment. This study proposes a new method of scoring the N5 subscale. Objectives: The aim of the present study was to develop a new scoring guide for the PANSS N5 Similarities and Proverbs scale and to assess inter-rater reliability using the newly developed scoring guide. Method: The authors analysed responses to PANSS questions of subjects who completed a double blind, randomized, placebo controlled clinical trial of oral naltrexone for treatment of alcohol use disorders in schizophrenia. Results: Of the 90 subjects, 45 had schizophrenia and 45 had schizoaffective disorder. 95% of subjects had alcohol dependence, 5% had alcohol abuse. Subjects consumed a median of 21 standard drinks per week at study entry. Participants had low to moderate PANSS Positive, Negative, and General Psychopathology scores. 434 different responses to similarities and 748 different responses to proverbs were sorted independently by two psychologists using a newly developed scoring guide for N5. The guide sorted responses into 4 categories, from correct to marginal, to concrete, to incorrect; examples of almost each type of responses were provided in the guide. Inter-rater reliability for scoring all Similarities responses was 93%, Weighed Cohen Kappa 0.83, p< .001; for scoring all Proverbs was 87%, Weighted Cohen Kappa 0.62, p<.001. Conclusion: Strong inter-rater reliability was achieved using a newly-developed scoring guide for Similarities and Proverbs of PANSS. The Guide could be used to improve accuracy of scoring PANSS N5.