Quantitative Assessment of Caregiver Quality of Life Across Dementia Severity Using a Utility-Weighted Scale Based on a Conjoint Analysis

Objective Neurobehavioral symptoms of dementia substantially impair the quality of life (QOL) of caregivers. However, most caregiver burden instruments are ordinal and lack empirically derived symptom-specific weighting, limiting quantitative interpretation. This study aimed to develop a utility-weighted scale to quantitatively assess caregiver QOL impairment across the dementia severity levels. Methods Eleven dementia-related neurobehavioral symptoms were identified through a literature review and interviews with 115 dementia care professionals. Utility weights were estimated using a conjoint analysis based on the rankings of 27 hypothetical dementia profiles. The resulting Caregiver Quality of Life (CgQOL) scale was evaluated for reliability and validated in individuals with Alzheimer's disease using the Zarit Burden Interview (ZBI), Functional Assessment Staging Tool (FAST), and Mini-Mental State Examination (MMSE). Results A conjoint analysis revealed a clear hierarchy of symptom importance, with agitation having the highest relative importance (15.5%), followed by difficulties with toileting (12.1%) and sleep disturbances (11.7%). The total CgQOL scores ranged from 0 to 36.3. The scale demonstrated excellent inter-rater reliability (weighted κ=0.86) and internal consistency (Cronbach's α=0.998). CgQOL scores increased monotonically with advancing FAST stage and were negatively correlated with the MMSE scores. Moderate convergent validity was observed with the ZBI scores, thus indicating that the two instruments captured related but distinct aspects of the caregiver burden. Conclusion The CgQOL scale is a novel parametric utility-weighted instrument that quantitatively captures caregiver QOL impairment associated with dementia-related neurobehavioral symptoms and complements existing caregiver burden measures. This framework enables a more nuanced and quantitative evaluation of caregiver burden and may serve as a complementary tool to conventional scales in both clinical and research settings.