Importance of adult literacy in understanding health disparities.

BACKGROUND: In several recent studies, the importance of education and race in explaining health-related disparities has diminished when literacy was considered. This relationship has not been tested in a nationally representative sample of U.S. adults.
OBJECTIVE: To understand the effect of adult literacy on the explanatory power of education and race in predicting health status among U.S. adults.
DESIGN: Using the 1992 National Adult Literacy Survey, logistic regression models predicting health status were estimated with and without literacy to test the effect of literacy inclusion on race and education.
SUBJECTS: A nationally representative sample of 23,889 noninstitutionalized U.S. adults. MEASURES: Poor health status was measured by having a work-impairing condition or a long-term illness. Literacy was measured by an extensive functional skills test.
RESULTS: When literacy was not considered, African Americans were 1.54 (95% confidence interval, 1.29 to 1.84) times more likely to have a work-impairing condition than whites, and completion of an additional level of education made one 0.75 (0.69 to 0.82) times as likely to have a work-impairing condition. When literacy was considered, the effect estimates of both African-American race and education diminished 32% to the point that they were no longer significantly associated with having a work-impairing condition. Similar results were seen with long-term illness.
CONCLUSIONS: The inclusion of adult literacy reduces the explanatory power of crucial variables in health disparities research. Literacy inequity may be an important factor in health disparities, and a powerful avenue for alleviation efforts, which has been mistakenly attributed to other factors.