Criterion-related and construct validation of the disability assessment for Dementia scale

Healthcare professionals measure functional disabilities in daily living tasks in order to monitor disease progress and implement intervention strategies. Few measurement tools assessing these problems in the community-dwelling elderly with Dementia of the Alzheimer's Type (DAT) currently exist. Recently, the Disability Assessment for Dementia Scale (DAD) was developed to assess disabilities in activities of daily living experienced by this population.The Disability Assessment for Dementia Scale (DAD) is a proxy-respondent scale measuring disability in daily living tasks in terms of executive functions. The objectives of this study were to measure the criterion-related (concurrent) validity and the construct validity of this scale. Total score correlational analyses between the Rapid Disability Rating Scale-2 and the Disability Assessment for Dementia Scale were used to estimate criterion-related (concurrent) validity. In addition, the known-groups procedure was used to estimate criterion-related (concurrent) validity. Stage of dementia served as the known-group variable against which total DAD Scale scores were compared. Construct validity was estimated using total score correlational analyses between the Burden of Care Scale and the Disability Assessment for Dementia Scale (DAD). Likewise, construct validity was estimated using total score correlational analyses between the standardized Mini Mental Status Examination (MMSE) and the DAD Scale. Correlations proved highly significant for criterion-related (concurrent) validity measures r = $-$0.84, and for known-groups procedure estimates r = $-$0.73. Results for construct validity measures were r = $-$0.29 for Burden of Care scores and r = 0.55 for MMSE scores. Interpretations for these findings were offered in the discussion of this project. Findings indicated that the Disability Assessment for Dementia Scale is a valid disability measurement for community-dwelling Alzheimer's subjects, and support its use in this type of DAT population