Correlates and barriers to medication adherence in multiple sclerosis patients and their impact on clinical outcomes

Abstract Background: Multiple sclerosis (MS), a debilitating, chronic disease of the central nervous system, is the most common cause of neurological defects in young adults. There are currently over a dozen disease-modifying therapies (DMTs) that reduce relapse rates and slow disease progression. Despite positive efficacy studies, there are many barriers to medication adherence, which may impact patient outcomes. Aims: The purpose of this study is to evaluate the correlation between medication adherence and clinical outcomes and to identify barriers to adherence in the MS patients filling DMT prescriptions at Yale New Haven Health Outpatient Pharmacy Services (OPS). Methods: This retrospective study was conducted with 138 adult patients filling MS medications at OPS between 1 January 2018 and 31 July 2018. Subjective adherence and outcomes data were obtained through semi-annual MS patient assessments. The following data were evaluated for correlation with medication adherence: age, gender, ethnicity, language, smoking status, alcohol dependency, PMH of depression, Charlson comorbidity index, medication frequency and route, insurance provider, and medication co-pay. Retrospective medication possession ratio (MPR) data were collected from the pharmacy dispensing system, and hospital admissions obtained through the electronic health record (EHR). Results: Adherence data demonstrated that 3.6% of patients had an MPR <80% and 15.2% had an MPR <90%. A statistically significant correlation (p < .05) was identified between patients with a diagnosis of depression and patients with an MPR <80%, suggesting a correlation between worsening adherence and increasing depressive symptoms. A statistically significant correlation (p < .05) was identified between patients with hospital admissions or ED visits due to MS symptoms and patients with an MPR <80% as well as the cumulative MPR results, suggesting a correlation between worsening adherence and increasing hospital admission or ED visits due to MS. Conclusions: Patients with lower adherence to DMTs were associated with a higher rate of hospital admissions or ED visits due to MS symptoms documented in the EHR indicating the importance of medication adherence for this patient population. The importance of mental health for patients should be emphasized in this population as increasing depression symptoms were correlated with decreasing medication adherence.