Validation of the Retardation Rating Scale for detecting depression in geriatric inpatients

OBJECTIVES: Validation in the elderly of the Retardation Rating Scale (RRS), which includes items related to motor and mental retardation but not vegetative items, and may be particularly well-suited for the diagnosis of depression in the elderly. METHODS: One hundred and sixty-five geriatric inpatients (105 depressed), aged 65 and over, without dementia, neuroleptic medication and increased risk of slowed mobility, were assessed with the RRS and three validated 'gold-standard' scales for geriatric depression (Hamilton Depression Rating Scale, Montgomery and Asberg Depression Rating Scale, Geriatric Depression Scale). Factor analysis used varimax rotation, Cronbach's, Spearman's and Ferguson's coefficients and the Mann-Whitney U-test to evaluate construct and internal consistency. Convergent validity and Receiver Operating Characteristics curves were also analyzed. RESULTS: Factor analysis retained three interpretable domains: (1) motor items (45% of the variance); (2) mental items and (3) the cognitive items. Internal consistency was high (alpha = 0.91). Each item was strongly correlated with the total RRS score and associated with depression. The RRS showed good convergent validity and its total score increased with depression severity. A cut-off score of 10 yielded 79% sensitivity and 80% specificity, with 80% of the patients properly classified, that is 15% more than standard observer scales. CONCLUSION: RRS is a valid screening tool for depression and improves recognition of depression in geriatric inpatients.