Background: Previous assessments of informal care time have tended to consider only the amount of time spent with the patient by the primary informal caregiver; however, in many cases, more than one person is providing care for the patient. We assess total informal care time of people caring for patients with dementia, and estimate the bias that can arise if consideration is not made of the time spent by all participating informal caregivers.
Method: We used an extended version of the questions on informal care time from the Resource Utilization in Dementia (RUD) instrument. Caregivers were asked to state the number of days and the number of hours on a typical day they had assisted the patient in activities of daily living (ADL), instrumental ADL (IADL), and supervision during the last four weeks. Multivariate regression analyses were conducted to identify factors that could account for the amount of informal care time.
Results: 357 informal caregivers took part. Values were missing from only 4.5% of all interviews. On average, the primary informal caregiver cared for the patient 1.5, 2.1 and 1.9 hours per day in ADL, IADL and supervision respectively. Fifty-seven percent of all patients had more than one informal caregiver. Total informal care time was underestimated by about 14% if the time of caregivers other than the primary caregiver was not taken into account. The informal care time was significantly higher if the caregiver was the patient's partner and the patient's health status was lower.
Conclusion: Our results show that most previous studies probably underestimated costs of informal care because the time of informal caregivers other than the primary caregiver was not considered.