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

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: We sought 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) and print literacy (Short Test of Functional Health Literacy in Adults) 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: A total of 284 adults participated: age, 48 ± 14 years, 71% females, 70% African American, 6% Latino, mean FEV₁ 66% ± 19%, 86 (30%) with hospitalizations, and 148 (52%) with emergency department visits for asthma in the prior year. Mean Asthma Numeracy Questionnaire score was 2.3 ± 1.2 (range, 0-4); mean Short Test of Functional Health Literacy in Adults score was 31 ± 8 (range, 0-36). In unadjusted analyses, numeric and print literacy were associated with better adherence (P =.01 and P =.08, respectively), asthma control (P =.005 and P <.001, respectively), and quality of life (P <.001 and P <.001, respectively). After controlling for age, sex, and race/ethnicity, the associations diminished and only quality of life (numeric P =.03, print P =.006) and asthma control (print P =.005) remained significantly associated with literacy. Race/ethnicity, income, and educational attainment were correlated (P <.001). Conclusion: While the relationship between literacy and health is complex, interventions that account for and address the literacy needs of patients may improve asthma outcomes.