Mediators and Moderators of Improvements in Medication Adherence

In a randomized controlled trial we compared two models of community health worker-led diabetes medication decision support for low-income Latino and African American adults with diabetes. Most outcomes were improved when community health workers used either an interactive e-Health tool or print materials. This article investigates mediators and moderators of improved medication adherence in these two models.

Because both programs significantly improved satisfaction with medication information, medication knowledge, and decisional conflict, we examined whether improvements in each of these outcomes in turn were associated with improvements in self-reported medication adherence, and if so, whether these improvements were mediated by improvements in diabetes self-efficacy or diabetes distress. Potential moderators of improvement included gender, race/ethnicity, age, education, insulin use, health literacy, and baseline self-efficacy, diabetes distress, and A1c.

A total of 176 participants (94%) completed all assessments. After adjusting for potential confounders, only increased satisfaction with medication information was correlated with improved medication adherence ( p = .024). Improved self-efficacy, but not diabetes distress, was associated with improvements in both satisfaction with medication information and medication adherence. However, the Sobel-Goodman Mediation test did not support improvements in self-efficacy as a mechanism by which improved satisfaction led to better adherence. None of the examined variables achieved statistical significance as moderators.

Improvements in satisfaction with medication information but not in medication knowledge or decision conflict were associated with improvements in medication adherence. Interventions that target low-income ethnic and racial minorities may need to focus on increasing participants' satisfaction with information provided on diabetes medications and not just improving their knowledge about medications. Future research should explore in more depth other possible mediators and moderators of improvements in medication adherence in low-income minority populations.