A new generation rating scale for depression: Reliability and validity of the Italian version of Symptoms of Depression Questionnaire (SDQ), an RDoC-oriented depression comprehensive assessment

Objectives: The DSM-5 criteria for Depression has implicitly assumed either an endophenotype approach and other prognostically relevant features such as anxiety, irritability and anger. The new use of "specifiers" is consistent with the Research Domain Criteria (RDoC) framework, but new assessment tools able to capture such multidimensionality are needed. In this study we explored reliability of the Symptoms of Depression Questionnaire (SDQ), a rating scale developed by the Massachusetts General Hospital's research group for evaluating depression which contains five subscales correlated to specific circuits, according to the RDoC framework. Methods: This is a cross-sectional study performed between November 2016 and April 2017. After a translation and cross-cultural adaptation procedure, 207 healthy subjects and 36 patients completed the Italian version of SDQ to explore psychometric properties. Other instruments such as Beck Depression Inventory (BDI), Beck Anxiety Inventory (BAI) and the Suicide Behaviors Questionnaire-Revised (SBQ-R) were also administered for demonstrating convergent and discriminant validity. Results: Results showed that SDQ scores were significantly higher for patients with MDD when compared to healthy controls. Therefore Italian adaptation of SDQ presented a satisfactory capacity in discriminating between healthy subjects and patients. The Italian version of SDQ presented a satisfactory internal consistency (Cronbach α = 0.93) and test-retest reliability (Pearson r = .82). Correlations with BDI, BAI and SBQ-R supported concurrent validity. Cut-off scores of Italian version of SDQ has been calculated using the procedure of the original study. Conclusions: The present study confirms the reliability and validity of the Italian version of the SDQ, which showed a good construct validity, a good internal consistency, and a good degree of reproducibility. The use of instruments as SDQ developed on growing scientific evidence is crucial to move forward to a more precision medicine approach, on the road to personalized treatment.