The Quick Inventory of Depressive Symptomatology-Self-report: a psychometric evaluation in patients with asthma and major depressive disorder.

BACKGROUND

Despite the high co-occurrence between depression and asthma, few studies have addressed methods assessing the severity of depressive symptoms among patients with asthma.

OBJECTIVE

To evaluate the psychometric properties of the Quick Inventory of Depressive Symptomatology-Self-report (QIDS-SR16), a 16-item measure of depressive symptom severity, in patients with asthma.

METHODS

The psychometric properties of the QIDS-SR16 were compared at treatment exit with those of the 30-item self-report Inventory of Depressive Symptomatology (IDS-SR30) and the 17-item clinician-rated Hamilton Rating Scale for Depression (HRSD17) in 73 outpatients with asthma who were treated with citalopram or placebo for nonpsychotic major depressive disorder. Correlations between the depression rating scales and the Mini Asthma Quality of Life Questionnaire were calculated.

RESULTS

Internal consistency at exit was strong for the QIDS-SR16 (Cronbach alpha values are .87 for the QIDS-SR16, .95 for the IDS-SR30, and .87 for the HRSD17). The QIDS-SR16 and HRSD17 total scores were highly correlated (r = 0.85), as were the QIDS-SR16 and IDS-SR30 total scores (r = 0.97). All QIDS-SR16 item total score correlations were significant (P < .001). The QIDS-SR16, IDS-SR30, and HRSD17 showed comparable sensitivity to symptom change, indicating high concurrent validity for all 3 scales. The total QIDS-SR16 baseline to exit change score demonstrated a significant negative correlation (r = -0.49, P < .001) with the Mini Asthma Quality of Life Questionnaire. Thus, greater depressive symptom severity was associated with lower asthma-related quality of life.

CONCLUSIONS

The QIDS-SR16 showed good reliability and impressive construct validity. Strong psychometric properties of this brief self-report format and its sensitivity to treatment change suggest that the QIDS-SR16 is a valuable clinical tool.