Zoe C Campbell, Jessica K Dawson, Suzanne M Kirkendall, Kirsten J McCaffery, Jesse Jansen, Katrina L Campbell, Vincent Ws Lee, Angela C Webster

Low health literacy affects 25% of people with chronic kidney disease (CKD) and is associated with increased morbidity and death. Improving health literacy is a recognised priority, but effective interventions are not clear. This review looked the benefits and harms of interventions for improving health literacy in people with CKD. We searched the Cochrane Kidney and Transplant Register of Studies up to 12 July 2022 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov. We also searched MEDLINE (OVID) and EMBASE (OVID) for non-randomised studies. We included randomised controlled trials (RCTs) and non-randomised studies that assessed interventions aimed at improving health literacy in people with CKD. Two authors independently assessed studies for eligibility and performed risk of bias analysis. We classified studies as either interventions aimed at improving aspects of health literacy or interventions targeting a population of people with poor health literacy. The interventions were further sub-classified in terms of the type of intervention (educational, self-management training, or educational with self-management training). Results were expressed as mean difference (MD) or standardised mean difference (SMD) with 95% confidence intervals (CI) for continuous outcomes and risk ratios (RR) with 95% CI for dichotomous outcomes. We identified 120 studies (21,149 participants) which aimed to improve health literacy. There were 107 RCTs and 13 non-randomised studies. No studies targeted low literacy populations. For the RCTs, selection bias was low or unclear in 94% of studies, performance bias was high in 86% of studies, detection bias was high in 86% of studies reporting subjective outcomes and low in 93% of studies reporting objective outcomes. Attrition and other biases were low or unclear in 86% and 78% of studies, respectively. Compared to usual care, low certainty evidence showed educational interventions may increase kidney-related knowledge (14 RCTs, 2632 participants: SMD 0.99, 95% CI 0.69 to 1.32; I² = 94%). Data for self-care, self-efficacy, quality of life (QoL), death, estimated glomerular filtration rate (eGFR) and hospitalisations could not be pooled or was not reported. Compared to usual care, low-certainty evidence showed self-management interventions may improve self-efficacy (5 RCTs, 417 participants: SMD 0.58, 95% CI 0.13 to 1.03; I² = 74%) and QoL physical component score (3 RCTs, 131 participants: MD 4.02, 95% CI 1.09 to 6.94; I² = 0%). There was moderate-certainty evidence that self-management interventions probably did not slow the decline in eGFR after one year (3 RCTs, 855 participants: MD 1.53 mL/min/1.73 m², 95% CI -1.41 to 4.46; I² = 33%). Data for knowledge, self-care behaviour, death and hospitalisations could not be pooled or was not reported. Compared to usual care, low-certainty evidence showed educational with self-management interventions may increase knowledge (15 RCTs, 2185 participants: SMD 0.65, 95% CI 0.36 to 0.93; I² = 90%), improve self-care behaviour scores (4 RCTs, 913 participants: SMD 0.91, 95% CI 0.00 to 1.82; I² =97%), self-efficacy (8 RCTs, 687 participants: SMD 0.50, 95% CI 0.10 to 0.89; I² = 82%), improve QoL physical component score (3 RCTs, 2771 participants: MD 2.56, 95% CI 1.73 to 3.38; I² = 0%) and may make little or no difference to slowing the decline of eGFR (4 RCTs, 618 participants: MD 4.28 mL/min/1.73 m², 95% CI -0.03 to 8.85; I² = 43%). Moderate-certainty evidence shows educational with self-management interventions probably decreases the risk of death (any cause) (4 RCTs, 2801 participants: RR 0.73, 95% CI 0.53 to 1.02; I² = 0%). Data for hospitalisation could not be pooled. Interventions to improve aspects of health literacy are a very broad category, including educational interventions, self-management interventions and educational with self-management interventions. Overall, this type of health literacy intervention is probably beneficial in this cohort however, due to methodological limitations and high heterogeneity in interventions and outcomes, the evidence is of low certainty.