Construct Validity of the Kessler Psychological Distress Scale (K-10) Instrument in the Elderly with Disabilities: Rasch Model Analysis

Abstract

Aging contributes to functional decline and heightened psychological distress that affects the older adults’ quality of life. The World Health Organization (WHO) recommends the 10-item Kessler Psychological Distress Scale (K-10) for assessing psychological distress, however the Classical Test Theory (CTT)-based evaluation method has limitations. Item Response Theory (IRT), specifically the Rasch model, offers a more accurate method for measuring the instrument’ validity and reliability. This study examined the construct validity of the K-10 Indonesian version in older adults with disabilities. A cross-sectional method and secondary data from 321 elderly individuals (≥60 years) with disabilities in Bandung City, Indonesia, were used between August and February 2025. The Instrument’s construct validity of was analyzed by performing the Rasch model. A total of 315 responses were eligible for analysis. The K-10 showed an overall fit to the Rasch model (mean outfit MnSq = 1.03±0.27). Item C10 (“feel worthless”) was identified as misfitting (outfit MnSq >1.4; ZSTD >2), although no factor bias was detected. The explained variance reached 54.10%. Reliability indicators were strong, with a Cronbach’s alpha of 0.89 and a person separation index above 2. However, category functioning and targeting did not fully meet Rasch expectations. The correlation between K-10 and WHODAS 2.0 showed a moderate positive relationship, though it did not reach the criterion for convergent validity (r >0.6).  The Indonesian version of the K-10 has acceptable construct validity in a sample of older adults with disabilities in Bandung City, Indonesia.