[Quantification of dementia-related disabilities in daily behavior with the DAFS (Direct Assessment of Functional Status): reliability and validity of a German test version].

The DAFS (Direct Assessment of Functional Status) is a new test for the assessment of competence of demented patients in situations of everyday life. The present study assesses objectivity, temporal stability, concurrent and discriminative validity of a German version of the DAFS. Sixteen patients with a DSM-III-R-diagnosis of dementia of the Alzheimer's type, 8 of which with a mild (MMSE 18-25) and 8 with a moderate (MMSE 12-17) dementia, and 8 control subjects without any symptoms of dementia (MMSE 28-30), matched with the patient groups in age, gender and education, were assessed three times within 3 weeks with the DAFS and once with the NOSGER (an ADL rating scale). The DAFS showed high objectivity (correlation between two test administrators r = .97) and stability (2 week retest reliability r = .98) and was able to discriminate significantly between the study groups and with a strong effect size. Correlations with the total score and the IADL subscale score of the NOSGER were high (r = .81 and r = .86, resp.), whereas correlations with the mood and the disturbing behavior subscale were much lower (both r = .54). This investigation could demonstrate that the DAFS is an objective, stable and valid test instrument. It has a high power to discriminate between demented and non-demented subjects as well as between various degrees of severity of illness. The test items are highly relevant for everyday functioning and the test itself is a good and necessary addition to the use of ADL or IADL rating scales.