A 3-Item Screening Scale for Caregiver Burden in Dementia Caregiving: Scale Development and Score Mapping to the 22-Item Zarit Burden Interview

Abstract

ObjectivesBrief screening scales for caregiver burden are much needed in routine dementia services to efficiently identify caregivers of persons with dementia (PWD) for further intervention. Although the 22-item Zarit Burden Interview (ZBI) is often used, its available screening versions have not performed as well as the full version in distinguishing significant burden. We developed a brief screening scale that is valid and comparable to ZBI in distinguishing caregiver burden. Design and settingBaseline data of an ongoing cohort study. ParticipantsFamily careivers of community-dwelling PWD (n = 394). MeasuresParticipants completed questionnaires containing ZBI and other caregiving scales. Initially, we split the study samples into 2—the derivation sample (n = 215) was used to develop a brief scale that best distinguishes significant burden (using the best-subset approach with 10-fold cross-validation), whereas the validation sample (n = 179) verified its actual performance in distinguishing significant burden. We then evaluated the derived scale in its internal consistency reliability, factorial validity, known group validity, and construct validity, and mapped the scores between the brief scale and ZBI using the equipercentile equating method. ResultsWe derived a 3-item scale which had comparable performance to ZBI in distinguishing significant burden (area under the receiver operating characteristic curve 0.86, 95% confidence interval 0.81-0.92). It had a single dimension in exploratory factor analysis and maintained good psychometric properties similar to those of ZBI. It also explained 77.8% of the variability in ZBI, and had scores that could be mapped to ZBI with reasonable precision. Conclusions and ImplicationsWe have derived a highly accessible tool to screen for caregiver burden, which can have a wider health system effect of expanding the reach of caregiver-focused interventions to services involved in the care of PWD. Notably, this screening tool was developed using rigorous methods and demonstrated comparability to ZBI in its validity, reliability, and total scores.