Reliability and Validity of the Bipolar Prodrome Symptom Interview and Scale-Full Prospective in Its Turkish Translation

Background: No scale exists to assess patients at-risk for bipolar disorder (BD) in Turkey. We aimed to assess the psychometric properties of the Turkish version of the Bipolar Prodrome Symptom Interview and Scale-Full Prospective (BPSS-FP). Method: Psychiatric service users aged 11-18 years old were interviewed using the BPSS-FP translated into Turkish and the Kiddie Schedule for Affective Disorders and Schizophrenia. Youth with major depressive disorder (MDD, n = 63), bipolar-spectrum disorder (n = 47), and healthy controls (n = 122) were included. Cronbach's alpha was calculated to assess internal consistency. The Young Mania Rating Scale (YMRS) and Children's Depression Rating Scale-Revised (CDRS-R) were administered to test convergent/discriminant validity. Discriminant validity was further tested using one-way ANOVA and "receiver operating characteristic" (ROC) curves. Inter-rater reliability was tested using correlation coefficients. Findings: Across 232 youth, Cronbach's alpha values were 0.932 for the BPSS-FP total score, 0.878 for the Mania Symptom Index, 0.887 for the Depression Symptom Index, and 0.797 for the General Symptom Index. Correlation coefficients for inter-rater reliability were high for the Mania Symptom Index (r = 0.989), Depression Symptom Index (r = 0.973), and General Symptom Index (r = 0.981). There were high correlations between the BPSS-FP Mania Symptom Index subscore and YMRS (r = 0.732), and the BPSS-FP Depression Symptom Index subscore and CDRS-R (r = 0.754), whereas cross-polarity correlations were non-significant. ROC analysis cut-off value was >= 21 for the BPSS-FP Mania Symptom Index between patients with BD and MDD (specificity = 85.7%, sensitivity = 78.7%). Conclusion: The Turkish version of the BPSS-FP has good psychometric properties and can be used in research. Longitudinal studies are needed to confirm the predictive value of the BPSS-FP.