Original Article
Short-form Zarit Caregiver Burden Interviews were valid in advanced conditions

https://doi.org/10.1016/j.jclinepi.2009.06.014Get rights and content

Abstract

Objectives

To assess six short-form versions of Zarit Burden Interview (ZBI-12, ZBI-8, ZBI-7, ZBI-6, ZBI-4, and ZBI-1) among three caregiving populations.

Study Design and Setting

Secondary analysis of carers' surveys in advanced cancer (n = 105), dementia (n = 131), and acquired brain injury (n = 215). All completed demographic information and the ZBI-22 were used. Validity was assessed by Spearman correlations and internal consistency using Cronbach's alpha. Overall discrimination ability was evaluated using the area under the receiver operating characteristic curve (AUC).

Results

All short-form versions, except the ZBI-1 in advanced cancer (rho = 0.63), displayed good correlations (rho = 0.74–0.97) with the ZBI-22. Cronbach's alphas suggested high internal consistency (range: 0.69–0.89) even for the ZBI-4. Discriminative ability was good for all short forms (AUC range: 0.90–0.99); the best AUC was for ZBI-12 (0.99; 95% confidence interval [CI]: 0.98–0.99) and the second best for ZBI-7 (0.98; 95% CI: 0.96–0.98) and ZBI-6 (0.98; 95% CI: 0.97–0.99).

Conclusions

All six short-form ZBI have very good validity, internal consistency, and discriminative ability. ZBI-12 is endorsed as the best short-form version; ZBI-7 and ZBI-6 show almost equal properties and are suitable when a fewer-question version is needed. ZBI-4 and ZBI-1 are suitable for screening, but ZBI-1 may be less valid in cancer.

Section snippets

Background

What is new?

Key findings

  1. The 12-item Zarit Burden Interview (ZBI-12) was suitable in all situations; the ZBI-7 and the ZBI-6 were almost equally good and may be suitable for palliative care settings; the ZBI-4 and ZBI-1 were useful when a very short screening instrument was needed.

What was known?
  1. The ZBI-22 is a widely used outcome measure of caregiver burden and has been validated in diverse caregiving samples. Several short-form versions of ZBI have been developed, but little is known about how well they perform in

Design and data sources

This is a secondary analysis using data pooled from four studies.

  • 1.

    Baseline data from a multicenter evaluation of palliative day care for cancer patients involving six centers across the south of England [22], [23];

  • 2.

    Baseline data from a two-center evaluation of the “90 Minute Group,” a supportive intervention for the carers of cancer palliative care patients [6];

  • 3.

    A national postal questionnaire survey of caregiver experiences of acquired brain injury (ABI) [24]; and

  • 4.

    Baseline data from a prospective

Results

One hundred and five, 131, and 215 informal carers for patients with advanced cancer, dementia, and ABI respectively, were recruited, making a total sample of 451. Most carers were women—81% for ABI, 72% for cancer, and 72% for dementia (χdf=22 = 5.50, P = 0.06). The carers of ABI patients were the youngest—mean age (standard deviation) of 54 (11) compared with 66 (12) for cancer and 62 (13) for dementia (F(2,448) = 42.8, P < 0.0001). Spouse/partner carers were the most common—59% for ABI, 82% for

Discussion

We tested and validated six short forms of the ZBI in three caregiving populations. In all groups, there was a wide range of scores for the ZBI-22; therefore, the short forms were tested in samples reporting varying caregiver burden. However, the highest burden scores were in the dementia and the ABI groups, and we were not able to test burden scores above 34 in the advanced cancer group. It may be that caregiver burden using ZBI was lower in advanced cancer compared with dementia and ABI

Conclusions

We found strong validity and internal consistency for each of the short-form versions in all three samples. The ZBI-12 is suitable in all situations, whereas the ZBI-7 or the ZBI-6 is suitable when a fewer-question version is needed, for example, in palliative care setting. The ZBI-7 is equivalent to the ZBI-6 although with one more question. The ZBI-4 and ZBI-1 may be useful when a very short screening instrument is needed, but the ZBI-1 may be less valid in cancer.

Acknowledgments

We thank the patients, carers, staff, and volunteers who participated in the original studies, including (1) six day and home hospice and palliative care services which recruited and interviewed patients and carers and Danielle Goodwin and other interviewers in the study; (2) two home palliative care services in London, Celia Leam and Liz Taylor who worked with us to recruit patients, and Alison Pearce (research assistant); (3) Research assistants Shehla Kazim, Amanda Tadrous, and Joel Sheridon

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    Competing interests: None.

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