The Spanish version of the Quick Inventory of Depressive Symptomatology-Self-Report (QIDS-SR16): a psychometric analysis in a clinical sample

Background: Psychometrically robust and easy-to-administer scales for depressive symptoms are necessary for research and clinical assessment. This is a psychometric study of the Spanish version of the Quick Inventory of Depressive Symptomatology-Self-Report (QIDS-SR16) in a clinical sample.

Method: One-hundred and seventy-three patients (65% women) with a psychiatric disorder including depressive symptoms were recruited. Such symptoms were assessed by means of the QIDS-SR16 and two interviewer-rated instruments: the 17-item Hamilton Depression Rating Scale (HDRS17) and the Clinical Global Impression-Severity (CGI-S) scale. Self-rated measures of health-related quality of life, subjective happiness and perceived social support were also obtained. Dimensionality, internal consistency, construct validity, criterion validity, and responsiveness to change of the QIDS-SR16 were examined.

Results: Exploratory and confirmatory factor analyses replicated the original one-factor structure. The Spanish version of the QIDS-SR16 showed good to excellent internal consistency (α=0.88), convergent validity [HDRS17 (r=0.77), CGI-S (r=0.78)], and divergent validity [EuroQol-5D Visual Analogue Scale (r=-0.78), Subjective Happiness Scale (r=-0.72)]. The QIDS-SR16 was excellent in discriminating clinically significant from non-significant depressive symptomatology (area under ROC curve=0.93). It also showed a high sensitivity to treatment-related changes: patients with greater clinical improvement showed a greater decrease in QIDS-SR16 scores (p<0.001).

Limitations: The study was conducted in a single center, which may limit the generalizability of the findings.

Conclusions: The Spanish version of the QIDS-SR16 retains the soundness of metric characteristics of the original version which makes the scale an invaluable instrument to assess depressive symptoms.