Reliability, validity and psychometric properties of the Greek translation of the zung depression rating scale

Introduction: The current study aimed to assess the reliability, validity and psychometric properties of the Greek translation of the Zung Depression Rating Scale (ZDRS). Methods: The study sample included 40 depressed patients 29.65 +/- 9.38 years old and 120 normal comparison subjects 27.23 +/- 10.62 years old. In 20 of them (12 patients and 8 comparison subjects) the instrument was re-applied 1-2 days later. Translation and Back Translation was made. Clinical Diagnosis was reached by consensus of two examiners with the use of the SCAN v. 2.0 and the IPDE. Statistical Analysis included ANOVA, the Pearson Product Moment Correlation Coefficient, Principal Components Analysis and Discriminant Function Analysis and the calculation of Cronbach's alpha (alpha) Results: Both Sensitivity and specificity exceed 90.00 at 44/45, Chronbach's alpha for the total scale was equal to 0.09, suggesting that the scale covers a broad spectrum of symptoms. Factor analysis revealed five factors (anxiety-depression, thought content, gastrenterological symptoms, irritability and social-interpersonal functioning). The test-retest reliability was satisfactory (Pearson's R between 0.92). Conclusion: The ZDRS-Greek translation is both reliable and valid and is suitable for clinical and research use with satisfactory properties. Its properties are similar to those reported in the international literature, although the literature is limited. However one should always have in mind the limitations inherent in the use of self-report scales.