Multiple sclerosis (MS) is a chronic disease of the CNS.5 Beginning in the 1990s, disease-modifying therapies (DMTs) were introduced that advanced management of MS, resulting in reduced rates of both relapse and disability progression.5 Today, 13 DMTs are available to treat relapsing MS: seven self-injectable drugs, three intravenous agents, and three oral compounds. Drug monographs for these agents can be found here.

The three oral disease-modifying drugs—fingolimod, teriflunomide, and dimethyl fumarate—all were approved in the past decade and have an efficacy at least equivalent to established injectable drugs.1 Due to serious safety risks, including liver injury and immune conditions, the recently approved long-acting self-injectable, daclizumab (Zinbryta) should generally only be used in patients with an inadequate response to two or more MS drugs. According to the US Food and Drug Administration, the agent “is available only through a restricted distribution program under a Risk Evaluation and Mitigation Strategy.”4 Due to substantial safety concerns, the three intravenous drugs—mitoxantrone, natalizumab (Tysabri), and alemtuzumab (Lemtrada)—are restricted to treating aggressive forms of MS1.

As with other chronic diseases, comorbidities are common in individuals with MS, which can adversely affect health outcomes. What’s little known, however, is whether such comorbidities delay initiation or affect initial selection of a DMT.

One of the first studies to examine comorbidity and treatment decisions in patients with MS hypothesized that the presence of comorbidities would reduce DMT use and influence choice of DMT for those with MS.5 Comorbidities of interest included the physical (diabetes, hypertension, hyperlipidemia, ischemic heart disease, chronic lung disease, and epilepsy), and the mental (anxiety, depression, bipolar disorder).

The Canadian Institutes of Health Research Team in the Epidemiology and Impact of Comorbidity on Multiple Sclerosis study included 10,698 persons with incident MS, half of whom had 1 or more comorbidities. Mean age at index date was 43.1 years. The reference group was 1995/1996–1999; others were 1989–1994, 2000–2004, 2005–2010/2012. The analysis focused on first-line injectable DMTs, since oral DMTs were not approved.5