Psychometric evaluation of the 5-item Medication Adherence Report Scale questionnaire in persons with multiple sclerosis.

The 5-item Medication Adherence Report Scale (MARS-5) is a reliable and valid questionnaire for evaluating adherence in patients with asthma, hypertension, and diabetes. Validity has not been determined in multiple sclerosis (MS). We aimed to establish criterion validity and reliability of the MARS-5 in persons with MS (PwMS). Our prospective study included PwMS on dimethyl fumarate (DMF). PwMS self-completed the MARS-5 on the same day before baseline and follow-up brain magnetic resonance imaging (MRI) 3 and 9 months after treatment initiation and were graded as highly and medium adherent upon the 24-cut-off score, established by receiver operator curve analysis. Health outcomes were represented by relapse occurrence from the 1st DMF dispense till follow-up brain MRI and radiological progression (new T2 MRI lesions and quantitative analysis) between baseline and follow-up MRI. Criterion validity was established by association with the Proportion of Days Covered (PDC), new T2 MRI lesions, and Beliefs in Medicines questionnaire (BMQ). The reliability evaluation included internal consistency and the test-retest method. We included 40 PwMS (age 37.6 ± 9.9 years, 75% women), 34 were treatment-naive. No relapses were seen during the follow-up period but quantitative MRI analysis showed new T2 lesions in 6 PwMS. The mean (SD) MARS-5 score was 23.1 (2.5), with 24 PwMS graded as highly adherent. The higher MARS-5 score was associated with higher PDC (b = 0.027, P<0.001, 95% CI: (0.0134-0.0403)) and lower medication concerns (b = -1.25, P<0.001, 95% CI: (-1.93-(-0,579)). Lower adherence was associated with increased number (P = 0.00148) and total volume of new T2 MRI lesions (P = 0.00149). The questionnaire showed acceptable internal consistency (Cronbach α = 0.72) and moderate test-retest reliability (r = 0.62, P < 0.0001, 95% CI: 0.33-0.79). The MARS-5 was found to be valid and reliable for estimating medication adherence and predicting medication concerns in persons with MS.
Competing Interests: MJ: None declared IL: received consultation and/or speaker fees from: Novartis. GBJ: participated as a clinical investigator and/or received consultation and/or speaker fees from: Biogen, Janssen, Lek, Merck, Novartis, Pliva/Teva, Roche, Sanofi Genzyme, Swixx. LS: participated as a clinical investigator and/or received consultation and/or speaker fees from: Bayer, Biogen, Boehringer Ingelheim, Genzyme, Janssen, Krka, Merck, Novartis, Pfizer, Roche, Sandoz, Sanofi, Viatris and Pliva/Teva. KŠP: None declared ŽŠ: received consultation and/or speaker fees from: Biogen, Novartis, Roche, Sanofi Genzyme. UR: participated as a clinical investigator and/or received consultation and/or speaker fees from: Bayer, Biogen, Sanofi Genzyme, Merck, Novartis, Pliva/Teva, Roche. MK: Research contracts with Krka, Vizera, Clinres, Pharmalinea with the aim of statistical analysis and a grant from AstraZeneca as a support to developments of sustainability and resilience of the healthcare system after COVID-19 pandemic. This does not alter our adherence to PLOS ONE policies on sharing data and materials.
(Copyright: © 2024 Jožef et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)