Validation of two short versions of the Zarit Burden Interview in the palliative care setting: a questionnaire to assess the burden of informal caregivers

Martina B Kühnel,Christina Ramsenthaler,Claudia Bausewein,Farina Hodiamont,Martin Fegg

doi:10.1007/s00520-019-05288-w

Martina B Kühnel, Christina Ramsenthaler + Show 3 more

Open Access

https://doi.org/10.1007/s00520-019-05288-w

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Abstract

PurposeSeveral validated outcome measures, among them the Zarit Burden Interview (ZBI), are valid for measuring caregiver burden in advanced cancer and dementia. However, they have not been validated for a wider palliative care (PC) setting with non-cancer disease. The purpose was to validate ZBI-1 (ultra-short version and proxy rating) and ZBI-7 short versions for PC.MethodsIn a prospective, cross-sectional study with informal caregivers of patients in inpatient (PC unit, hospital palliative support team) and outpatient (home care team) PC settings of a large university hospital, content validity and acceptability of the ZBI and its structural validity (via confirmatory factor analysis (CFA) and Rasch analysis) were tested. Reliability assessment used internal consistency and inter-rater reliability and construct validity used known-group comparisons and a priori hypotheses on correlations with Brief Symptom Inventory, Short Form-12, and Distress Thermometer.ResultsEighty-four participants (63.1% women; mean age 59.8, SD 14.4) were included. Structural validity assessment confirmed the unidimensional structure of ZBI-7 both in CFA and Rasch analysis. The item on overall burden was the best item for the ultra-short version ZBI-1. Higher burden was recorded for women and those with poorer physical health. Internal consistency was good (Cronbach’s α = 0.83). Inter-rater reliability was moderate as proxy ratings estimated caregivers’ burden higher than self-ratings (average measures ICC = 0.51; CI = 0.23–.69; p = 0.001).ConclusionThe ZBI-7 is a valid instrument for measuring caregiver burden in PC. The ultra-short ZBI-1 can be used as a quick and proxy assessment, with the caveat of overestimating burden.

Highlights

According to the WHO definition, palliative care (PC) addresses the needs of patients and offers a support system to help the family cope during the patients’ illness and in bereavement [1]
The aim of this study was (1) to test the Zarit Burden Interview (ZBI)-7, the ZBI-6, and the ZBI-1 short versions for content validity, structural validity, construct validity, and reliability in the PC setting; (2) to confirm findings using Rasch analysis; (3) to evaluate the suitability of ZBI-1 as a proxy assessment for staff members; and (4) to evaluate the suitability of ZBI-1 item as an ultra-short instrument for quick assessment based on validity, reliability, and Rasch analysis
Our aim for this study was to close the gap of a formal validation of the ZBI short versions in the PC setting

Summary

Introduction

According to the WHO definition, palliative care (PC) addresses the needs of patients and offers a support system to help the family cope during the patients’ illness and in bereavement [1]. A systematic review by Michels et al showed that the majority of studies measuring informal caregiver outcomes in PC use Support Care Cancer carer-specific measures, primarily measures of caregiver burden [10]. According to Michels et al the Zarit Burden Interview (ZBI) [11] is one of the two most frequently used measures of burden [10], the other one being the caregiver reaction assessment (CRA) [12]. Higginson et al validated ZBI short versions in advanced conditions with caregivers of patients with advanced cancer, dementia, and acquired brain injury (ABI) [18]. It was reported that the ZBI-1 might be suitable for screening [18]

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