Psychometric Properties of an Indian Translation of the Vision-related Activity Limitation Item Bank in Cataract.

ABSTRACT

SIGNIFICANCE: The Indian translated and culturally adapted version of the vision-related activity limitation (VRAL) item bank is a validated instrument to assess the difficulty in performing daily activities by cataract patients and can also be used to capture self-reported changes in ability to perform daily activities after cataract surgery. PURPOSE: The purpose of this study was to document (a) translation, cross-cultural adaptation of VRAL item bank into an Indian language, and (b) its validation using Rasch analysis in a South Indian cataract population. METHODS: At the first stage, a translated Indian version of VRAL item bank was produced using recommended procedures. At the second stage, Rasch analysis was performed to investigate its psychometric properties in 787 cataract patients (mean age, 58.2 years; mean ± SD visual acuity [logMAR], 1.19 ± 0.96 at baseline in eye for surgery) including comparison with the original version. RESULTS: Post-translation equivalence of meaning was achieved, but some English phrases required cross-cultural adaptation. Subsequently, all items were appropriate for the Indian culture, and VRAL item bank demonstrated excellent measurement precision (7.39). Dimensionality assessment suggested that VRAL construct may contain other dimensions such as self-care and visual search, and mobility. Self-care and visual search formed a unidimensional measure but was highly correlated with main VRAL dimension, and the removal of its items weakened precision of the main VRAL dimension measurement. Taken together, evidence favored retaining self-care and visual search items in a larger VRAL item bank. Mobility subscale lacked adequate measurement precision, so it was not examined further; again, items were retained in VRAL scale because they strengthened its measurement properties. Majority of items (99%) did not demonstrate notable differential item functioning (>1.0 logit) by presenting visual acuity (median, 0.20 logMAR) in the better-seeing eye. CONCLUSIONS: Items in the translated Indian VRAL item bank measure the same construct as the English version and fulfilled the psychometric requirements for use in cataract patients.