Health Literacy and Medical Adherence in Hemodialysis Patients: The Mediating Role of Disease-Specific Knowledge

Background: Kidney failure patients with low health literacy are at increased risk for poor self-care and negative health outcome. Objectives: This study aimed to examine the role of health literacy in patient’s knowledge about kidney disease and medical care adherence and also to test the mediating role of kidney knowledge on the relationship between health literacy and medical adherence among patients undergoing dialysis. Patients and Methods: This cross-sectional study was performed on 240 consecutive patients diagnosed with end stage renal disease (ESRD) referred to dialysis ward affiliated to Tehran University of Medical Sciences from March 2014 to June 2014 based on the inclusion criteria. Results: A total of 204 patients under dialysis, with a mean age of 50.9 years, answered to all questionnaires, including Mini Mental State Examination (MMSE), Short Test of Functional Health Literacy in Adults (S-TOFHLA), Kidney Knowledge Survey (KiKS) and End-Stage Renal Disease Adherence Questionnaire (ESRD-AQ). The results indicated that health literacy was inadequate in 25%, marginal in 9.8%, and adequate in 65.2% of the patients. Kidney knowledge (P 0.001), and adherence (P 0.02) scores differed significantly by health literacy levels. Health literacy was positively related to kidney knowledge (β = 0.08, SE = 0.01) and adherence (β = 1.04, SE = 0.37). Kidney knowledge was positively associated with adherence behaviors (β = 5.3, SE = 1.9). The Sobel test indicated that kidney knowledge (z = 2.6, P = 0.008) was a significant mediator of the influence of health literacy on adherence. Conclusions: Those with inadequate health literacy had lower kidney knowledge and lower adherence compared to those with adequate health literacy. After controlling for education, health literacy was significantly associated with kidney knowledge and adherence. Patients with higher health literacy had higher kidney knowledge and adherence behaviors. In addition, knowledge was a mediator of health literacy and adherence relationship. These findings demonstrate the high prevalence of low-health literacy in Iranian population and the health literacy is an important consideration in promoting disease-specific knowledge and adherence behaviors among patients with dialysis.