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Psychometric evaluation of the 5-item Medication Adherence Report Scale questionnaire in persons with multiple
Maj Jožef1,2, Igor Locatelli1, Gregor Brecl Jakob2
1Chair of Social Pharmacy, Faculty of Pharmacy, University of Ljubljana, Ljubljana, Slovenia.
Abstract:
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.
Insights
The Medication Adherence Report Scale-5 (MARS-5) is a valid tool for assessing medication adherence in multiple sclerosis patients. Higher adherence scores correlate with better treatment adherence and fewer new MRI lesions.
Area of Science:
- Neurology
- Pharmacology
- Medical Assessment
Background:
- The 5-item Medication Adherence Report Scale (MARS-5) is established for asthma, hypertension, and diabetes but not validated for multiple sclerosis (MS).
- Assessing medication adherence is crucial for managing chronic conditions like MS, impacting treatment efficacy and disease progression.
Purpose of the Study:
- To establish the criterion validity and reliability of the MARS-5 questionnaire in persons with multiple sclerosis (PwMS).
- To evaluate the association between MARS-5 scores and objective measures of adherence and health outcomes in PwMS initiating dimethyl fumarate (DMF).
Main Methods:
- A prospective study involving 40 PwMS on DMF, who completed the MARS-5 before baseline and follow-up brain MRIs at 3 and 9 months.
- Criterion validity was assessed by correlating MARS-5 scores with Proportion of Days Covered (PDC), new T2 MRI lesions, and the Beliefs in Medicines questionnaire (BMQ).
- Reliability was evaluated using internal consistency (Cronbach's alpha) and test-retest methods.
Main Results:
- The MARS-5 demonstrated acceptable internal consistency (Cronbach's α = 0.72) and moderate test-retest reliability (r = 0.62).
- Higher MARS-5 scores correlated significantly with higher PDC (b = 0.027, P<0.001) and lower medication concerns (b = -1.25, P<0.001).
- Lower adherence, indicated by lower MARS-5 scores, was associated with a greater number and volume of new T2 MRI lesions (P = 0.00148 and P = 0.00149, respectively).
Conclusions:
- The MARS-5 is a valid and reliable instrument for assessing medication adherence in persons with multiple sclerosis.
- The MARS-5 can effectively predict medication concerns and identify individuals at risk for poorer adherence and potential disease progression in MS.
