Objective:
To test theorized patient-level mediators in the causal pathway between health literacy (HL) and 1-year mortality among adults with cardiovascular disease (CVD)
Patients and Methods:
3,000 adults treated at Vanderbilt University Hospital from October 11, 2011 to December 18, 2015 for acute coronary syndrome or acute decompensated heart failure (ADHF) participated in the Vanderbilt Inpatient Cohort Study. Participants completed a bed-side administered survey and consented to health record review and longitudinal follow-up. Multivariable mediation models examined the direct and indirect effects of HL (a latent variable with 4 indicators) with 1-year mortality post-discharge (dichotomous). Hypothesized mediators included social support, health competence, health behavior, comorbidity index, type of CVD diagnosis, and prior year hospitalizations.
Results:
Of the 2,977 patients discharged from the hospital (60% male, mean age 61 years, 83% non-Hispanic White, 37% admitted for ADHF), 17–23% had inadequate HL depending on measure, and 10% died within 1 year. The total effect of lower HL on 1-year mortality (AOR=1.31 [95% CI, 1.01, 1.69]) was decomposed into an indirect effect (AOR=1.50 [1.35, 1.67]) via the mediators and a nonsignificant direct effect (AOR=0.87 [CI, 0.66, 1.14]). Each standard deviation decrease in HL was associated with an absolute 3.2 percentage point increase in the probability of 1-year mortality via mediators admitted for ADHF, comorbidities, health behavior, health competence, and prior hospitalizations (by contribution to indirect effect).
Conclusion:
Patient-level factors drive the relationship between low HL and mortality. Health competence and health behavior are modifiable mediators that could be targeted by interventions.