The impact of health literacy and socioeconomic status on asthma disparities.

Objective: Racial/ethnic disparities have been well documented in asthma. While socioeconomic status (SES) has been repeatedly implicated as a root cause, the role of limited health literacy has not been extensively studied. The purpose of this study was to examine the independent contributions of SES and health literacy in explaining asthma disparities.

Methods: A cohort study was conducted in a Chicago-based sample of 353 adults aged 18-40 years with persistent asthma from 2004 to 2007. Health literacy, SES, and asthma outcomes including disease control, quality of life, emergency department visits, and hospitalizations were assessed in person at baseline, and asthma outcomes were measured every 3 months for 2 years by phone. Multivariate models were used to assess racial/ethnic disparities in asthma outcomes and the effect of health literacy and SES on these estimates.

Results: Compared with White participants, African American adults fared significantly worse in all asthma outcomes (p < .05) and Latino participants had lower quality of life (β = -0.47; 95% confidence interval [CI] = -0.79, -0.14; p = .01) and worse asthma control (risk ratio [RR] = 0.63; 95% CI = 0.41, 0.98; p = .04). Differences in SES partially explained these disparities. Health literacy explained an additional 20.2% of differences in quality of life between Latinos and Whites, but differences in hospitalization rates between African American and White adults remained (RR = 2.97; 95% CI = 1.09, 8.12, p = .03).

Conclusions: Health literacy appears to be an overlooked factor explaining racial and ethnic disparities in asthma. Evidence-based low literacy strategies for patient education and counseling should be included in comprehensive interventions.