A valid instrument for measuring informal care time for people with dementia.

OBJECTIVE: An economic evaluation of dementia-related interventions from a societal perspective should take account of informal caregiving. We assessed informal caregiving time and report our findings on the validity and stability of our results.
METHODS: Within the German IDA study ('Dementia Care Initiative in Primary Practice'), informal care time for people with dementia living at home is assessed. We applied a German adaptation of the Resource Utilization in Dementia (RUD) questions on informal care, which distinguishes three categories of informal care activities: Activities of Daily Living (ADL), Instrumental ADL (IADL), and supervision. In contrast to the original version, we included the time of all informal caregivers who are involved in caring for the patient. The questionnaire was completed as a computer-assisted telephone interview at baseline and after 1 year. To test the plausibility of the questionnaire, we proposed seven hypotheses about the reported informal care time.
RESULTS: Nearly all results confirmed our hypotheses. Informal care time as well as changes over time correlated with the physical and mental health status of the patient. Considering the time of other informal caregivers led to slightly higher correlations (not significant). The results indicate that interviewees seem to underestimate particularly the time of supervision of other informal caregivers.
CONCLUSION: In sum, the instrument gives plausible results and is suited for measuring informal care time, as well as changes over time. If it is not possible to directly interview each caregiver involved, it is of great importance to identify and interview the primary informal caregiver in order to prevent an underestimation of total informal care time.