Title:Development and Psychometric Validation of the 27 Item Zarit Caregiver
Interview for Alzheimer’s Disease (ZCI-AD-27)
Volume: 19
Issue: 13
Author(s): Coen A. Bernaards*, Kathrin I. Fischer, Angela J. Rylands, Adam Gater, Chloe Tolley, Steven H. Zarit and Claire J. Lansdall
Affiliation:
- Department of Product Development Data Sciences, Genentech, Inc., South San Francisco, USA
Keywords:
Alzheimer’s disease, caregiver, Zarit Burden Interview, Zarit Caregiver Interview, psychometrics, caregiverreported outcomes, validation.
Abstract:
Background: Caring for an individual with Alzheimer’s disease (AD) is an allencompassing
challenge that affects daily life. Assessment of the care partner experience is needed to
support the development and evaluation of successful interventions for people with AD and their care
partners. We developed the 27-item Zarit Caregiver Interview for Alzheimer’s Disease (ZCI-AD-27)
to assess the impact of informal caregiving in the context of AD.
Objective: We assessed the psychometric validity of the ZCI-AD-27 in a population of care partners
for individuals with moderate AD, and established thresholds for meaningful score change.
Methods: Secondary data were obtained from informal care partners of participants in a clinical trial
(NCT01677754). Psychometric analyses were conducted to assess validity, reliability, and responsiveness
of the ZCI-AD-27. Anchor-based and distribution-based methods were performed to determine
clinically meaningful score change.
Results: The ZCI-AD-27 had a 12-domain factor structure, including a second-order domain termed
Humanistic impact that included four key domains (Physical, Emotional, Social, and Daily life) as
confirmed by confirmatory factor analysis with the adequate fit. Internal consistency (Cronbach’s alpha
ranging from 0.66 to 0.93 for domains), convergent validity, and discriminant validity indicated
the good performance of the ZCI-AD-27. Known-groups validity analyses showed a greater impact on
care partners with increasing disease severity. Responsiveness results demonstrated that the ZCI-AD-
27 is sensitive to change over time and meaningful change analyses indicated a range of meaningful
score changes in this population.
Conclusion: The ZCI-AD-27 is a comprehensive, psychometrically valid measure to assess the impact
of caring for individuals with moderate AD.
