Low health literacy and multiple medications in community-dwelling older adults: a population-based cohort study.

Abstract

Adequate health literacy is important for patients to manage chronic diseases and medications. We examined the association between health literacy and multiple medications in community-dwelling adults aged 50 years and older in England. We included 6368 community-dwelling people of median age 66 years from the English Longitudinal Study of Ageing. Health literacy was assessed at wave 5 (2010/11) with 4 questions concerning a medication label. Four correct answers were categorised as adequate health literacy, otherwise low. Data on medications were collected at wave 6 (2012/13). To examine the difference in the number of medications between low and adequate health literacy, we used zero-inflated negative binomial regression, estimating odds ratio (OR) for zero medication and incidence rate ratios (IRR) for the number of medications, with 95% CIs. Associations were adjusted for demographic, socioeconomic and health characteristics, smoking and cognitive function. We also stratified the analysis by sex, and age (50-64 and ≥65 years). To be comparable with preceding studies, multinomial regression was fitted using commonly used thresholds of polypharmacy (0 vs 1-4, 5-9, ≥10 medications). Although low health literacy was associated with a lower likelihood of being medication-free (OR=0.64, 95% CI: 0.45 to 0.91), health literacy was not associated with the number of medications among those at risk for medication (IRR=1.01, 95% CI: 0.96 to 1.05), and this finding did not differ among younger and older age groups or women. Among men, low health literacy showed a weak association (IRR=1.06, 95% CI: 0.99 to 1.14). Multinomial regression models showed graded risks of polypharmacy for low health literacy. Although there was no overall association between health literacy and the number of medications, this study does not support the assertion that low health literacy is associated with a notably higher number of medications in men.