The short version of the Japanese version of the Zarit caregiver burden interview (J-ZBI-8): Its reliability and validity

Abstract

The Zarit Burden Interview (ZBI) is the instrument most widely used in North America and Europe for assessing the burden experienced by family caregivers who look after the community-residing impaired elderly. The Japanese version of the ZBI (J-ZBI) is the most widely used in Japan for the same purpose. We used data from 691 caregivers in relation to their caregiver burden with the 22-item J-ZBI. Following a factor analysis, the 8-item short version of the J-ZBI, the J-ZBI-8, was proposed with the following two factors: Personal strain (5 items) and Role strain (3 items). Cronbach' s alpha of the J-ZBI-8 was 0.89, indicating the high reliability of this instrument. Pearson' s correlation coefficient between J-ZBI and J-ZBI-8 was 0.93, and the same coefficient between J-ZBI-8 and item 22 (a single global burden) was 0.68. These data indicated that J-ZBI-8 had a high concurrent validity. In addition, caregivers who declared that they did not encounter any difficulties in looking after the impaired elderly had a significantly lower J-ZBI-8 score (3.45 ; SD = 4.57) than those who claimed that they had such difficulties (9.31; SD = 7.19) by the t-test; this indicated that J-ZBI-8 had a high construct validity. These results indicated that the short version, the J-ZBI-8, had a high reliability and validity. Therefore, the J-ZBI-8 produced results comparable to those of the full version, i.e. the J-ZBI. The shorter yet no less reliable and valid 8 item version will thus lead to easier administration of the instrument for assessing family caregiver burden in clinical settings.