Could the Quick Inventory of Depressive Symptomatology-Self-Report (QIDS-SR) be used in depressed schizophrenia patients?

Abstract

BackgroundDeveloping accurate and time-efficient tools to measure depressive symptoms in schizophrenia is important for research and clinical practice. This study tested the psychometric properties of the Chinese version of the 16-item Quick Inventory of Depressive Symptomatology (QIDS-SR) in depressed schizophrenia patients. MethodsThis study included 337 clinically stable patients with schizophrenia. The severity of depressive symptoms was assessed using the Montgomery–Asberg Depression Rating Scale (MADRS), QIDS-SR at baseline and 2 weeks later. Negative symptoms and extrapyramidal symptoms were measured with the negative symptom score of Brief Psychiatric Rating Scale (BPRS) and the Simpson–Angus Scale of Extrapyramidal Symptoms (SAS), respectively. ResultsInternal consistency (Cronbach׳s alpha) was 0.73 and 0.67 for QIDS-SR at the baseline and endpoint, respectively. The intra-class correlation coefficient (ICC) for test–retest reliability over the two weeks was 0.77. Two domains (involvement and energy) at baseline and one domain (energy) at endpoint had the highest item-total correlations. The QIDS-SR total score was significantly correlated with the MADRS total score at baseline (r=0.44, p<0.01). Weak correlations of the QIDS-SR score with the scores of the BPRS negative (r=0.18) and the SAS (r=0.05) indicate good discriminant validity. The QIDS-SR showed unidimensional measurement properties in exploratory factor analysis at both baseline. The main limitation of the study is that only clinically stable schizophrenia patients were included. ConclusionsThe QIDS-SR has acceptable psychometric properties in stable schizophrenia patients and may be useful in both research and clinical practice.