Pharmacy-based interventions for patients with limited health literacy and chronic disease: A systematic review of intervention outcomes with a focus on co-design.

BACKGROUND: Limited health literacy (LHL) is associated with poorer health outcomes and presents challenges for chronic disease management. Pharmacy-based interventions may support medication-related outcomes in this population; however, their effectiveness and the extent to which they incorporate co-design elements remain unclear. OBJECTIVES: To evaluate the effectiveness of pharmacy-based interventions for adults with chronic disease and LHL, and to examine the extent to which co-design elements are incorporated in intervention development. METHODS: MEDLINE, CINAHL, Embase, PsycINFO, and the Cochrane Central Register of Controlled Trials (CENTRAL) were searched from inception to 30 June 2025. Randomised controlled trials evaluating pharmacy-based interventions among adults with chronic disease and LHL were included. Study selection, data extraction, and quality appraisal were conducted independently by two reviewers. Risk of bias was assessed using the Joanna Briggs Institute Critical Appraisal Tool. Findings were synthesised narratively due to substantial heterogeneity. RESULTS: A total of 10,029 records were identified, with nine trials (13 publications) included. Intervention effects were heterogeneous across outcomes. Medication understanding improved most consistently, driven primarily by patient-centred medication labels, with more modest gains from universal medication schedules. Care-transition interventions showed reductions in adverse events in some trials, although findings were not consistent across trials. Medication adherence outcomes were inconsistent and not sustained across trials. Clinical outcomes were assessed less frequently and showed mixed effects. Evidence of differential effectiveness by health literacy was limited and inconsistently reported. Co-design elements were largely absent, with only one trial reporting patient and family involvement. All trials were rated as low or moderate risk of bias, with none at high risk. CONCLUSION: Pharmacy-based interventions demonstrate mixed effectiveness in individuals with LHL, with stronger evidence for improving medication understanding and potential benefits in care transitions, but inconsistent effects on adherence and clinical outcomes. Co-design remains under-utilised or under-reported. Future research should prioritise co-designed, theory-informed interventions and improve reporting of health literacy subgroup analyses and participatory development processes.