The association of health literacy with adherence and outcomes in moderate-severe asthma

Abstract

Background Low health literacy is associated with poor outcomes in asthma and other diseases but the mechanisms governing this relationship are not well-defined. Objective To assess whether literacy is related to subsequent asthma self-management, measured as adherence to inhaled steroids, and asthma outcomes. Methods In a prospective longitudinal cohort study, numeric (Asthma Numeracy Questionnaire (ANQ)) and print literacy (Short Test of Functional Health Literacy in Adults (S-TOFHLA)) were assessed at baseline in adults with moderate or severe asthma for their impact on subsequent electronically monitored adherence and asthma outcomes (asthma control, asthma-related quality of life, and FEV1) over 26 weeks, using mixed-effects linear regression models. Results 284 adults participated: 48±14 years, 71% female, 70% African American, 6% Latino, mean FEV1 66% ± 19%, 86 (30%) with hospitalizations and 148 (52%) with ED visits for asthma in the prior year. Mean ANQ score (range 0–4) was 2.3 ± 1.2; mean S-TOFHLA score 31 ± 8 (range 0–36). In unadjusted analyses numeric and print literacy were associated with better adherence (p=0.01, p=0.08), asthma control (p=0.005, p <0.001), and quality of life (p<0.001, p<0.001). After controlling for age, sex, and race/ethnicity, the associations diminished and only quality of life (numeric: p=0.03, print p=0.006) and asthma control (print p=0.005) remained significantly associated with literacy. Race/ethnicity, income, and educational attainment were correlated (p<0.001). Conclusion While the relationship between literacy and health is complex, interventions which account for and address the literacy needs of patients may improve asthma outcomes. Clinical Implications/Key Summary In adults with moderate or severe asthma, higher health literacy scores were associated with better subsequent quality of life and asthma control.

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