title: The validation of a caregiver assessment of dementia: the Dementia Severity Scale.
abstract: OBJECTIVE
  The objective of this study was to refine and validate the Dementia Severity Scale (DSS), a newly developed assessment of dementia severity from a caregiver's perspective. The Dementia Severity Scale is designed to measure deficits in activities of daily living (ADL), behavioral disturbances, and the caregiver's perception of the patient's current cognitive abilities.
  
  
  METHODS
  Community dwelling caregiver/patient dyads were recruited from 12 clinical sites. Patients had a primary dementia diagnosis for at least one year. In this cross-sectional study, caregivers were administered the Dementia Severity Scale, the Quality of Life-Alzheimer's Disease (QOL-AD), the Progressive Deterioration Scale (PDS), and the Neuropsychiatric Inventory (NPI). Patients were administered the Mini-Mental State Examination (MMSE) and the QOL-AD. To evaluate test-retest reliability, 25% of caregivers were randomized to a second visit.
  
  
  RESULTS
  One hundred eighty-three caregiver/patient dyads were recruited. Mean caregiver age was 67.5; mean patient age was 78.8; 93% of patients had probable Alzheimer disease. Eighty-eight (48.1%) patients were male. Exploratory factor analysis established 6 subscales (Activities of Daily Living [ADL], Instrumental ADL [IADL], Communication, Agitation, Memory, and Disorganized Thinking). Cronbach's alphas ranged from 0.82 to 0.90 for the 6 subscales. Test-retest reliability was good with intraclass correlation coefficients ranging from 0.79 to 0.89. DSS subscales were moderately-to-highly correlated with the QOL-AD, NPI, MMSE, and PDS. Subscales significantly discriminated among severity levels of dementia, identified by both physician ratings and MMSE scores.
  
  
  CONCLUSIONS
  The Dementia Severity Scale demonstrated excellent psychometric properties and appears to be useful both in clinical practice and research endeavors. Further research is needed to establish the longitudinal sensitivity of the Dementia Severity Scale to the progression of dementia.
authors.affiliation: Mt. Sinai School of Medicine, New York, New York 10029, USA. Philipdharvey1@cs.com
authors.forename: Philip D
authors.initials: PD
authors.lastname: Harvey
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Moriarty
authors.forename: Leah
authors.initials: L
authors.lastname: Kleinman
authors.forename: Karin
authors.initials: K
authors.lastname: Coyne
authors.forename: Carl H
authors.initials: CH
authors.lastname: Sadowsky
authors.forename: Michael
authors.initials: M
authors.lastname: Chen
authors.forename: Dario F
authors.initials: DF
authors.lastname: Mirski
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D017028:Caregivers / Q000523:psychology*; D003430:Cross-Sectional Studies; D003704:Dementia / Q000523:psychology*; D005260:Female; D006304:Health Status; D006801:Humans; D008297:Male; D011788:Quality of Life; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires