Development and Validation of a Multidimensional Short Version Zarit Burden Interview (ZBI-9) for Caregivers of Persons With Cognitive Impairment.

BACKGROUND: There is a lack of appreciation of the full dimensionality of the original 22-item Zarit Burden Interview (ZBI) in the development of short versions. Existing short versions are premised upon a 1-factor or 2-factor structure or statistical techniques for item selection. Thus, there is a need for ZBI short versions that considers the multidimensional constructs of role strain, personal strain, and worry about performance (WaP) during item selection to provide a more holistic and comprehensive evaluation.

PURPOSE: To develop and validate a short version of ZBI through a combined quantitative and qualitative approach that incorporates the validated 4-factor structure of role strain demands; role strain-control; personal strain, and WaP.

PATIENTS: We studied 202 caregivers of patients with dementia (84.2%) or mild cognitive impairment (15.8%) attending a memory clinic in Singapore.

METHODS: Confirmatory factor analysis and qualitative considerations from expert consensus were used for item selection. Confirmatory factor analysis fit statistics support the 4-factor structure. The 9-item ZBI-9 showed good internal consistency (Cronbach's α=0.87) and convergent validity with anxiety and depression (Pearson correlation: Hospital Anxiety and Depression sub-scales, r≥0.56, P<0.001; ZBI- 22, r=0.95, P<0.001). Using a cut-off score of ≥13, ZBI-9 displayed good discriminatory ability for depressive symptoms (area under curve=0.79, P<0.001; sensitivity=70%, specificity=75%). The ZBI-9 also displayed comparable performance to the 22-item full version and three 12-item short versions.

CONCLUSION: The ZBI-9 is a multidimensional short-version assessment tool for caregivers of persons with dementia and mild cognitive impairment that is reliable, valid, and discriminates depressive symptoms.