Research Decoder: Comorbidities

hA comorbidity is a chronic medical condition that occurs alongside an existing one. For example, someone diagnosed with both multiple sclerosis and hypertension would be said to have two comorbid conditions. Comorbidities are of paramount concern to clinicians and other care providers, since they can often interact with MS in unpredictable ways, in turn complicating the course or treatment of MS, impacting quality of life and influencing disease progression. A proper understanding of the types and frequencies of comorbidities among people living with MS is a crucial step in figuring out the optimal treatment and management plan that suits each individual. Comprehensive and accurate information on the population patterns of comorbidities is also indispensable for designing proper research studies in order to account for any complicating factors that could end up skewing the results.

An international initiative aimed at cataloguing the various types and frequencies of comorbidities in people living with MS, called the MS Comorbidities Project and led by the International Advisory Committee on Clinical Trials in MS, released a seven-part, systematic review of comorbidities in MS earlier this year. The reviews were co-authored by leading MS epidemiologist and neurologist Dr. Ruth Ann Marrie (supported by an MS Society Donald Paty Career Development Award) and a team of international colleagues, and together make up the most exhaustive overview of the MS comorbidity landscape to date. The reviews were broken up across six different categories of comorbid conditions: 1) sleep disorders and seizure disorders; 2) cardiac, cerebrovascular, and peripheral vascular disease; 3) psychiatric disorders; 4) autoimmune disease; 5) gastrointestinal, musculoskeletal, ocular, pulmonary, and renal disorders, and; 5) cancer.

The review came up with some highly important findings. Firstly, the five most common comorbidities found among people living with MS were depression, anxiety, hypertension, hypercholesterolemia and chronic lung disease. The most common autoimmune diseases in particular included thyroid disease and psoriasis. Strikingly, the authors found that some conditions, such as meningiomas and urinary system cancers, were more common in the MS population compared to the general population, whereas pancreatic, ovarian, prostate and testicular cancers were less common. Together, these findings show that there is an urgent need to include routine screening for certain comorbidities as a part of standard MS management.

Of course, there are many challenges to overcome when conducting a systematic literature review like this one; for instance, study designs and reporting methodologies can differ significantly from one study to another, and variable quality between studies can complicate matters further. One aim of the MS Comorbidities Project is to help standardize the design and quality of studies going forward.

Recently, Dr. Marrie and colleagues published an MS Society-funded study where they asked: do comorbid conditions affect health and survival in people living with MS? This question was driven by the observation that while people with MS are living longer now than ever before, their lifespans in general continue to be lower than people in the general population. They found that people with MS who had comorbidities such as depression, anxiety, diabetes, heart disease and chronic lung disease had an increased risk of dying at a younger age than people without these conditions; however, people without MS had a similar increased risk of shorter lifespan if they had the same medical conditions. Nonetheless, these results highlight the need to understand and treat these conditions in tandem with the management of MS. You can read the details of the study in our recent MS Update.

Do you have any comorbid conditions that exist alongside your MS? Share your story in the comments below.


Marrie RA et al. (2015). A systematic review of the incidence and prevalence of comorbidity in multiple sclerosis: Overview. Mult Scler. 21(3): 263-81.

Marrie RA et al. (2015). Effect of comorbidity on mortality in multiple sclerosis. Neurology. [Epub ahead of print]

Image credits: © Cornelius20 | – Brain Maze Photo

Categories Research

National vice-president, research, past MS researcher, and PhD in Cellular and Molecular Medicine from University of Ottawa. Leads the MS Society's research program to find the cure for MS and improve the quality of life for people affected by the disease.

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