Psychometric and Clinical Evaluation of the Clinician (VQIDS-C) and Self-Report (VQIDS-SR) Versions of the Very Quick Inventory of Depressive Symptoms.

PURPOSE

Evaluate the psychometric properties of the 5-item Very Quick Inventory of Depressive Symptomatology self-report and clinician-rated versions (VQIDS-SR/VQIDS-C), compare their relative performance, create crosswalks between their total scores and other accepted depressive symptom ratings, and define clinically relevant depressive symptom severity thresholds and categorical outcomes for both versions.

PATIENTS AND METHODS

The Sequenced Treatment Alternatives to Relieve Depression trial obtained baseline and exit 17-item Hamilton Rating Scale for Depression (HRSD) and 30-item Inventory of Depressive Symptomatology - Clinician-rated scores, and baseline and visit-wise QIDS-SR and QIDS-C ratings from the first treatment step (citalopram). The VQIDS-C and the VQIDS-SR items (sad mood, self-outlook, involvement, fatigue, psychomotor slowing) (each rated 0-3), extracted from the corresponding 16-item ratings, were selected to best reflect the 6-item HRSD (HRSD) (exclusive of anxiety). Classical Test Theory (CTT) and Item-Response Theory (IRT) analyses assessed psychometric features. IRT analyses produced total score crosswalks between the VQIDS, QIDS-C, QIDS-SR and HRSD. Clinically relevant VQIDS symptom severity thresholds and treatment outcomes were estimated based on cross-walks from the parent QIDS ratings.

RESULTS

Both VQIDS versions were unifactorial with acceptable internal consistencies (Cronbach's alphas >0.80), item-total correlations (0.57-0.74) by CCT, and strong IRT item performance. Based on QIDS severity thresholds (none 0-5; mild 6-10; moderate 11-15; severe 16-20; and very severe 21-27), comparable thresholds were 0-2; 3-5; 6-9; 9-12; and >12 for VQIDS-C, and 0-2; 2-5; 6-8; 9-12; and >12 for VQIDS-SR. Kappa values were acceptable in comparing categories of outcomes (eg, no benefit, remission, etc) based on VQIDS and corresponding QIDS categories.

CONCLUSION

The VQIDS-C and VQIDS-SR assess selected core depressive symptoms with psychometrically acceptable properties. Theelf-report and clinician-rated versions provide virtually identical information, symptom severity thresholds and symptom change categories. Both are as sensitive to change as the corresponding QIDS, making them suitable for use in busy practices.