Original Research

Adherence to Disease-Modifying Therapies in Patients With MS: A Retrospective Cohort Study

A significant number of patients diagnosed with multiple sclerosis are not receiving promising new disease-modifying agents.

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Multiple sclerosis (MS) is an autoimmune disorder in which the myelin of the brain and spinal cord is selectively targeted by immune-system cells. As a result, nerve transmission is disrupted, leading to a variety of unpredictable symptoms from weakness and a lack of balance to blindness and paralysis of the body. Clinically, MS can take 4 courses, including relapsing-remitting (RRMS), primary-progressive (PPMS), secondary-progressive, and progressive-relapsing.1 At onset, 85% of diagnosed patients have RRMS, and 10% to 15% have PPMS.2 If untreated, patients with RRMS become secondary-progressive, with progressive disability and indiscrete relapses.3 Hence, disease-modifying therapies are targeted toward decreasing the relapse rate as well as slowing the progression of the disease.4

Annually, about 16,000 veterans with MS receive health care services from the VHA.5 The C.W. Bill Young Bay Pines VA Healthcare System (BPVAHCS) is a level 1 facility that annually serves more than 105,000 veterans. The BPVAMC sees veterans with a wide variety of neurologic illnesses and has 5 full-time neurologists with subspecialty training. The BPVAHCS facility has outpatient clinics and a 200 inpatient bed facility. The Neurology Department sees 125 outpatients per week and consults on about 30 inpatients per week.


A retrospective review of BPVAHCS patients diagnosed with MS from January 2009 to July 2014 was performed with institutional review board approval. Patient data were collected from ICD-9-CM codes and kept confidential. A list of patients was collected from Neurology Clinic patient visits with “Multiple Sclerosis” on the problem list.

Patient medical records were reviewed to collect the following information: presence of rigorous diagnosis of MS, clinical course of MS in patient, presence or absence of disease-modifying therapy, and disease-modifying agents (DMAs) used.

Determining factors for DMA treatment included increasing tiredness, weakness, visual symptoms, and radiologic evidence (magnetic resonance imaging) of recurrent, active lesions. Each patient was examined on a case-by-case basis to assess whether or not the patient actually had MS and if so, whether they were being treated with DMAs. Only patients with RRMS were included. Patients were excluded from the study if they were deceased, not currently under BPVACHS care, or had symptoms of optic neuritis but were not fully indicative of MS. Patients with clinically isolated syndrome, probable diagnosis of MS, or PPMS also were excluded from the study.

Exclusion from this study was based on 2 additional premises. Patients were excluded if they discontinued an initial ABC (interferon beta-1a, interferon beta-1b, glatiramer acetate) due to DMA treatment relapse or adverse effects (AEs), such as injection site reactions, flulike symptoms, or depression. Additionally, patients who were not willing to take more DMA medications were excluded if they felt they were relatively stable (had infrequent relapses) and believed that additional medication was not worth the risk of potential AEs.

The study patients were seen and followed up by the neurologists. All the data for this study were based on interactions with the neurologists and not primary care providers (PCPs). Because MS treatment is complex, PCPs have little involvement in its management. The percentage of patients not on any DMAs was calculated from the list of BPVAHCS patients with RRMS.

The results were compared with a similar retrospective cohort study conducted using the Commercial Claims database and Medicare Supplemental and Coordination of Benefits database to identify individuals newly diagnosed with MS.6 This study was chosen because it was similar in methodology but investigated a comparable non-VA group. A 2-tailed difference between proportions test was then performed to determine whether the BPVAHCS patients with MS who were not treated with DMAs were significantly different from those from this non-VA population. Additionally, data from VA patients who were receiving DMAs were further examined and presented.


At the BPVAHCS, 262 patients were diagnosed with MS and 43% were not treated with DMAs. Margolis and colleagues found that about 60% of its 11,061 newly diagnosed non-VA patients with MS remained untreated.6 Although the latter proportion is higher, a 2-tailed difference between proportions test indicates that the proportion of patients with MS being treated at the VA was significantly lower (P < .01).

Among the 148 patients who were diagnosed with MS and treated with DMA at BPVAHCS, 5 different DMAs were identified (Table). The most commonly prescribed regimen was glatiramer acetate, which was used by 56 of 148 patients (37.8%). Fifty-two patients (35.1%) used interferon beta-1a. Of the 2 interferon DMAs, beta-1a was twice as popular as beta-1b, which was prescribed to 22 (14.9%) of patients. Dimethyl fumarate (6.8%) and fingolimod (5.4%) were used sparingly, because they were new to the market (cost and availability also were factors). With time, increased efficacy and objective assessment of benefit in the reduction of the T2 lesion load may result in a greater use of these oral DMAs.7–9


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