Patient‐reported impact of symptoms in schizophrenia scale (PRISS): Development and validation

Abstract

Background: We report the psychometric properties of the Patient-ReportedImpact of Symptoms in Schizophrenia Scale (PRISS), which assesses the impactof subjective experiences or qualia in outpatients with this condition.Methods: A cross-sectional study was carried out in 162 patients diagnosed withschizophrenia in Spain. The PRISS measures the presence, frequency, concernand interference with daily life of self-reported experiences related to the mainsymptoms observed in these patients. The psychometric analysis included test-retest reliability, internal consistency and structural and convergent validity.Results: The 28-item PRISS showed good test-retest reliability as 64.3% of theintraclass correlation coefficient values were between 0.40 and 0.79, which werestatistically significant (p < 0.01). Analysis of the structural validity revealed athree- factor structure, (1) productive subjective experiences, (2) affective-negativesubjective experiences and (3) excitation, which accounted for 56.11% of thevariance. Of the Pearson's correlation coefficients analysed between the PRISS and the Positive and Negative Syndrome Scale (PANSS), Scale for Assessmentof Negative Symptoms (SANS) and World Health Organization DisabilityAssessment Schedule (WHO-DAS), 72.2% were statistically significant (p < 0.05)and ranged from 0.38–0.42, 0.32–0.42 and 0.40–0.42, respectively.Conclusion: Our results indicate that the PRISS appears to be a brief, reliableand valid scale to measure subjective experiences in schizophrenia and providesvaluable information complementary to clinical evaluation.