A comparison of the screening potential of the geriatric depression scale (GDS) and the hospital anxiety and depression scale (HADS) in diagnosing depression at a geriatric day hospital setting
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Background Depression is a common condition in older people affecting approximately 10% of elderly people of all age groups living at home (Morgan et al 1987). Some studies suggest that prevalence is higher in those with medical conditions. There are several screening tools used in diagnosing depression, but it is unknown which tool is most effective in a setting such as the Medical Geriatric Day Hospital. Aim of this study was to compare the usefulness of two commonly used screening tools; the Geriatric Depression Scale (GDS) and the Hospital Anxiety and Depression Scale (HADS), by employing the Diagnostic and Statistical manual (DSM IV) as the "gold standard" method of diagnosing depression. Method Consecutive patients aged over 65 years attending the Medical Geriatric Day Hospital were recruited. GDS (15) and HADS were administered by a trained nurse. An independent Old Age Psychiatrist, blinded to the screening tool results, performed the DSM IV assessment in a standardised manner. Results 101 participants (58 women) were recruited. Mean age (SD; range) of the study population was 79.4 (6.7; 65-93) years. Prevalence of depression in the studied population using the DSM IV was 22.8%. Sensitivities and specificities(95%CI) of the GDS (15) in diagnosing depression were 78.3%(70.3-86.3) and 73.0%(64.4-81.6) and those of HADS were 69.6%(60.6-78.6) and 78.2%(70.1-86.3) respectively. Positive predictive values for GDS (15) and HADS were 46.2%(36.5-55.9) and 48.5%(38.7-57.7) and the negative predictive values were 91.9%(86.6-97.2) and 89.7%(83.8-95.6) respectively. False positive rates were 53.8%(44.1-63.5) and 51.5%(41.8-61.2) and false negative rates were 8.1%(2.8-13.4) and 10.3%(4.4-16.2) respectively. Conclusions Both GDS (15) and HADS had a relatively high negative predictive value suggesting that they may have value in ruling out depression. However the false positive rates mean that patients screened positive in both tools require a more comprehensive assessment as approximately half will not have depression. The two screening tools performed similarly.