Research regarding studies of the factor structure of the Zarit Burden Interview

The purpose of this research was to clarify the structure of factors in the Zarit Caregiver Burden Interview (ZBI) evaluation index using data for family members providing long-term care to persons in the home, and to examine applications for this index in Japan. The subjects were 1,143 individuals who as of April 1, 2002, were acting as the main caregivers for any of the 5,189 seniors living in Otsu City, Shiga Prefecture, certified as "Type 1 Insured Parties" after having received certification of eligibility for long-term care. All of the subjects agreed in advance to participate in this study. We analyzed data using an explanatory factor analysis (EFA) and a confirmatory factor analysis (CFA) to study the structural validity of the ZBI evaluation index. Based on the results of the analysis, we identified three factors: "Personal restrictions", "Emotional strain", and "Caregiving responsibility". Furthermore, based on the results of the confirmatory factor analysis, we formed a secondary factor model and a diagonal model that assume the inclusion of these factors. A primary factor model could not be established, however, because of indexes for goodness of fit of the data. Based on the results of a confirmatory factor analysis, we verified the validity of a diagonal model that includes the three factors in question. Because the primary factor model could not be established, we believe that further studies of the three factors indicated are still required. However, it is highly significant that in the case of the ZBI, a care burden index for family members providing care to seniors with dementia, the factor structure has already been verified, making it possible to identify the cause-and-effect relationships involved in feelings of care burden among family caregivers and the seniors with dementia for whom care is being provided.