Validation of the Optimal University of California Los Angeles Loneliness Scale Cutoff Score in Screening for the Prevention of Disability Occurrence Among Older Japanese Adults.

Objectives: The association between loneliness and disability is a growing public health priority. While the University of California Los Angeles Loneliness Scale (UCLA-LS) has been internationally used as an indicator for assessing loneliness, its optimal cutoff point in relation to disability occurrence has not yet been examined. Therefore, we aimed to determine the optimal cutoff point of the UCLA-LS regarding future disability.

Methods: This longitudinal cohort study was conducted in Tokai City, Aichi Prefecture, Japan. Overall, 4536 community-dwelling older adults (age: 73.8 ± 5.5 years; females: 55.2%) were followed up for 2 years. The area under the curve of the receiver operating characteristic analysis was calculated to evaluate the optimal cutoff point of the UCLA-LS in relation to future disability occurrence using the Youden index, which maximized the sensitivity and specificity of the UCLAS-LS. A survival analysis was conducted to test this cutoff value's external validity, using the presence or absence of disability occurrence as the dependent variable.

Results: The cutoff score of the UCLA-LS in relation to future disability was 44 points. An association was found between new disability occurrence and loneliness based on this cutoff value (hazard ratio: 1.67, 95% confidence interval: 1.29-2.16).

Conclusions: Although cultural context should be taken into account, the optimal cutoff scores for the loneliness scale related to disability identified in this study may be a useful indicator for early recognition of loneliness as a global public health problem and for promoting social participation as one of the disability prevention strategies.