a1 Istituto di Ricerche ‘Mario Negri’, Milan; United Medical and Dental Schools, Guy's Hospital, London and General Practice Research Unit, Institute of Psychiatry, London
The Organic Brain Syndrome (OBS) and the Depression (D) scales derived from the Comprehensive Assessment and Referral Evaluation (CARE) were translated into Italian and used in a survey of geriatric institutions in Milan. During the survey validity and reliability tests of the scales were conducted.
Inter-rater reliability (total score weighted kappa) was highly satisfactory for both scales (0·96 for OBS and 0·83 for D scale). Reliability was assessed three times during the survey and showed good stability for both scales, with a slight but significant trend towards reduction over time for the D scale. Reliability of the D scale was significantly lower when the subjects interviewed scored highly on the OBS scale (severe cognitive impairment).
Criterion validity was highly satisfactory both for the OBS scale (cut-off point 4/5: sensitivity 77%, specificity 96%, positive predictive value 91%) and the D scale (cut-off point 10/11: sensitivity 95%, specificity 92%, positive predictive value 84%).
Results are discussed with special reference to longitudinal assessment of reliability, the choice of the cut-off point, and the context-dependent properties of questionnaires.
c1 Address for correspondence: Dr A. Spagnoli, Istituto di Ricerche, ‘Mario Negri’, via Eritrea 62, Milan, Italy