Psychometric properties of the Quick Inventory of Depressive Symptomatology (QIDS-SR) in UK primary care.

It is widely believed that severity of depressive disorder should guide treatment selection and many guidelines emphasise this factor. The Quick Inventory of Depressive Symptomatology (QID-SR16) is a self-complete measure of depression severity which includes all DSM-IV criterion symptoms for major depressive disorder. The object of this study was to assess the psychometric properties of the QIDS-SR16 in a primary care sample. Adult primary care patients completed the QIDS-SR16 and were assessed by a psychiatrist (blind to QIDS-SR16) with the 17-item Hamilton Rating Scale for Depression (GRID-HAMD). Internal consistency, homogeneity and convergent and discriminant validity of the QIDS-SR16 were assessed. Severity cut-off scores for QIDS-SR16 were assessed for convergence with HRSD-17 cut-offs. Published methods for converting scores to HRSD-17 were also assessed. Two hundred and eighty-six patients participated: mean age = 49.5 (s.d. = 13.8), 68% female, mean HRSD-17 = 12.6 (s.d. = 7.6). The QIDS-SR16 exhibited acceptable internal consistency (Cronbach's alpha = 0.86), a robust factor structure indicating one underlying dimension and correlated highly with the HRSD-17 (r = 0.79) but differed significantly in how it categorised the severity of depression relative to the HRSD-17 (Wilcoxon Signed Rank Test p < 0.001). Using published methods to convert QIDS-SR16 scores to HRSD-17 scores did not result in alignment of severity categorisation. In conclusion, psychometric properties of the QIDS-SR16 were found to be strong in terms of internal consistency, factor structure and convergent and discriminant validity. Using conventional scoring and conversion methods the scale was found not to concur with the HRSD-17 in categorising the severity of depressive symptoms.

Measuring depression severity in general practice: discriminatory performance of the PHQ-9, HADS-D, and BDI-II.

BACKGROUND: The UK Quality and Outcomes Framework (QOF) rewards practices for measuring symptom severity in patients with depression, but the endorsed scales have not been comprehensively validated for this purpose. AIM: To assess the discriminatory performance of the QOF depression severity measures. DESIGN AND SETTING: Psychometric assessment in nine Scottish general practices. METHOD: Adult primary care patients diagnosed with depression were invited to participate. The HADS-D, PHQ-9, and BDI-II were assessed against the HRSD-17 interview. Discriminatory performance was determined relative to the HRSD-17 cut-offs for symptoms of at least moderate severity, as per criteria set by the American Psychiatric Association (APA) and NICE. Receiver operating characteristic curves were plotted and area under the curve (AUC), sensitivity, specificity, and likelihood ratios (LRs) calculated. RESULTS: A total of 267 were recruited per protocol, mean age = 49.8 years (standard deviation [SD] = 14.1), 70% female, mean HRSD-17=12.6 (SD = 7.62, range = 0-34). For APA criteria, AUCs were: HADS-D = 0.84; PHQ-9 = 0.90; and BDI-II = 0.86. Optimal sensitivity and specificity were reached where HADS-D ≥9 (74%, 76%); PHQ-9 ≥12 (77%, 79%), and BDI-II ≥23 (74%, 75%). For NICE criteria: HADS-D AUC = 0.89; PHQ-9 AUC = 0.93; and BDI-II AUC = 0.90. Optimal sensitivity and specificity were reached where HADS-D ≥10 (82%, 75%), PHQ-9 ≥15 (89%, 83%), and BDI-II ≥28 (83%, 80%). LRs did not provide evidence of sufficient accuracy for clinical use. CONCLUSION: As selecting treatment according to depression severity is informed by an evidence base derived from trials using HRSD-17, and none of the measures tested aligned adequately with that tool, they are inappropriate for use.