Background: Functional health literacy (FHL) and patient activation can impact diabetes control through enhanced diabetes self-management. Less is known about the combined effect of these characteristics on diabetes outcomes. Using brief, validated measures, we examined the interaction between FHL and patient activation in predicting glycosylated hemoglobin (HbA1c) control among a cohort of multimorbid diabetic patients.
Methods: We administered a survey via mail to 387 diabetic patients with coexisting hypertension and ischemic heart disease who received outpatient care at one regional VA medical center between November 2010 and December 2010. We identified patients with the study conditions using the International Classification of Diseases-Ninth Revision-Clinical Modification (ICD-9-CM) diagnoses codes and Current Procedure Terminology (CPT) procedures codes. Surveys were returned by 195 (50.4%) patients. We determined patient activation levels based on participant responses to the 13-item Patient Activation Measure and FHL levels using the single-item screening question, "How confident are you filling out medical forms by yourself?" We reviewed patient medical records to assess glycemic control. We used multiple logistic regression to examine whether activation and FHL were individually or jointly related to HbA1c control.
Results: Neither patient activation nor FHL was independently related to glycemic control in the unadjusted main effects model; however, the interaction between the two was significantly associated with glycemic control (odds ratio 1.05 [95% confidence interval 1.01-1.09], P=0.02). Controlling for age, illness burden, and number of primary care visits, the combined effect of these measures on glycemic control remained significant (odds ratio 1.05 [95% confidence interval 1.01-1.09], P=0.02).
Conclusion: The interaction between FHL and patient activation is associated with HbA1c control beyond the independent effects of these parameters alone. A personalized approach to diabetes management incorporating these characteristics may increase patient-centered care and improve outcomes for patients with diabetes.
Keywords: diabetes mellitus; health literacy; self-care; veterans.