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QUESTION: In older patients, are short scales as effective as long scales in screening for depression?
Design
Blinded comparison of 3 Geriatric Depression Scales (GDS-4, GDS-15, and GDS-30) and the Mental Health Inventory-1 (MHI-1) scale with diagnostic criteria of research of International Classification of Diseases—10th edition (DCR-10).
Setting
A teaching hospital in the UK
Patients
87 patients (mean age 79 y, 60% women) who were > 60 years of age and attended the day rehabilitation facility or were admitted to the medical rehabilitation wards. Patients were excluded if they had an illness, communication problems, or a score of < 6 on the 10-item Abbreviated Mental Test (AMT).
Description of tests and diagnostic standard
The GDS-30, GDS-4, 10-item AMT, and 5-item MHI were administered within 48 hours after an initial interview. Data for GDS-15 and MHI-1 were extracted from GDS-30 and MHI-5. Established cut points for diagnosis of depression were used for GDS-30, GDS-15, and GDS-4. The cut point for MHI-1 was set retrospectively. The clinical interview assessed mood and depression by using the DCR-10 (diagnostic standard).
Main outcome measures
Sensitivity, specificity, and area under the receiver operating characteristic (ROC) curve.
Main results
17 of the 87 patients (20%) were diagnosed with depression by using the DCR-10. Sensitivity, specificity, positive and negative likelihood ratios, and ROC curve results for all tests are in the tabled. The 4 tests did not differ for screening of depression.
Operating characteristics of short and long scales to screen for depression in older patients*
Conclusion
Short scales (Geriatric Depression Scale-4 and Mental Health Inventory-1) were comparable in sensitivity andspecificity to long scales (Geriatric Depression Scale-30 and Geriatric Depression Scale-15) in screening for depression in older patients.
QUESTION: In older patients, are short scales as effective as long scales in screening for depression?
Commentary
Depression is common, serious, and treatable, but it is under-recognised, particularly in elderly people. Societal and cultural biases often hinder the diagnosis.1 The study by Pomeroy et al compares 4 different screening instruments of variable length and content. The authors found that all 4 screening instruments had similar accuracy for detecting depression, and the 1-item MHI-1 had the best combination of sensitivity and specificity.
These results need further validation for 3 reasons: first, this study assessed a small inpatient sample; second, fewer than half of the patients approached were included in the study; and third, a relatively low interrater reliability (κ = 0.40) existed for MHI-1. Furthermore, the cut point for the MHI was defined retrospectively, and the item itself was not done independently and was extracted from a longer scale.
Should the clinician wait for further validation before implementing this approach to screening for depression? The answer is a resounding “no”! The literature on screening for depression in general medical outpatients2 suggests that all of the screening instruments are relatively comparable, with sensitivity and specificity ranging from 80% to 90%: similar to the findings in this study. In a typical setting, a positive test result might raise the probability of depression from 10% to 15% to 35% to 45%, and a negative test result might lower the probability of depression to < 5%. Ensuring that all patients are screened for depression regularly is more important than small changes in the precision of the screening instrument.3
Footnotes
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Source of funding: not stated.
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For correspondence: Professor I Philp, Sheffield Institute for Studies on Ageing, Northern General Hospital, Herries Road, Sheffield S5 7AU, UK.