Advancing health literacy measurement in old age

Abstract

Health literacy is described as a domain of competence across the life-span, gaining particular prominence in light of age-associated health restrictions. However, no specific measurement approach has been proposed for old age. The aim of this study is to augment the existing HLS-EU-Q16 scale (16 items) by items sensitive to age-specific aspects of health literacy to ensure validity and reliability for use in old age. In a first step, the HLS-EU-Q16 was administered in a sample of 463 individuals aged 72 - 92 years. Psychometric properties were evaluated using confirmatory factor analysis and item-response-theory item fit statistics. Scale reliability was found to be poor in this population segment. In a second step, age-specific items were developed based on qualitative in-depth interviews with older persons. In a third step, we tested if the additional set of age-specific items was able to enhance a valid and reliable measurement of health literacy in a second sample of older adults (N = 107, 49 - 91 years). With the inclusion of an eight-item add-on, it was possible to measure health literacy in old and very old age with both high validity and satisfying precision (reliability = 0.80). The study contributes to a population-specific measurement of health literacy.

Keywords: health literacy; item-response theory; measurement; mixed-methods design; old age.