Determinants of health literacy and its impact on illness perception in patients with multiple sclerosis: evidence from patient-reported outcomes.

Background: Health literacy (HL) is a key determinant of health outcomes, especially in chronic neurological diseases such as multiple sclerosis (MS). Insufficient HL may impair the ability of patients to manage their condition, reduce treatment adherence and increase the use of healthcare. Objective: To identify factors influencing HL among individuals with MS and to explore its association with illness perception and medication-related behaviours. Methods: Between April and September 2023, we consecutively enrolled 330 patients with MS from a single outpatient clinic. We included individuals aged 18-65 years with functional literacy, and we did not exclude participants based on MS subtype, education level, disability status or treatment characteristics. We assessed HL using the Newest Vital Sign, cognition using the Montreal Cognitive Assessment (MoCA), emotional status using the Hospital Anxiety and Depression Scale, and illness perception using the Brief Illness Perception Questionnaire (BIP-Q). We also evaluated self-reported medication adherence and perceived treatment benefits. After excluding 11 participants with incomplete data, we analysed 319 complete responses in accordance with Strengthening the Reporting of Observational Studies in Epidemiology guidelines. Results: Overall, 49.7% of participants demonstrated adequate HL. The HL correlated positively with MoCA scores and education (path coefficients: 0.117, 0.114) and negatively with disease duration, age and depression (-0.023,-0.029, -0.085). HL was positively associated with illness perception (BIP-Q coefficient: 1.558). The model explained 35.6% of the variance in HL and 5.7% in illness perception (R²=0.356; 0.057). Conclusion: Our findings suggest that routine HL assessment and targeted educational interventions may enhance understanding, adherence and informed decision-making, ultimately improving disease management and outcomes in MS.