Ruth Ann Marrie, MD, PhD: Comorbidities in Multiple Sclerosis

Ruth Ann Marrie, MD, PhD, FRCP, associate professor of medicine at the University of Manitoba: My long-term interest is the impact of comorbidity or co-existing health conditions in multiple sclerosis. We know that they are common in people with multiple sclerosis and are associated with a number of adverse outcomes, such as greater disability progression, increased symptoms of pain and fatigue, lower quality of life, as well as high mortality and increased health care utilization.

There are several challenges in dealing with people with comorbidities. One is that there are multiple conditions competing for your attention, and it is not always clear which one is causing which symptom. There are often multiple treatments required, and so sometimes they compete with each other and then there is the potential for adverse events of medications in combination. One important issue when we're looking at MS specific therapies - both the disease-modifying therapies to reduce relapses and disability progression as well as symptom management - is that patients with comorbidities are often excluded from clinical trials. That means we don't know if therapies work as well in those individuals, nor do we know if they're as safe.

There's now a recognition of the importance of comorbidity, both in terms of how frequently it occurs and that it increases with age and it affects treatment, that the international advisory committee on clinical trials in MS made some recommendations around being much more conscious about characterizing comorbidity status of patients in trials, trying to loosen up trial criteria a bit to allow more people with comorbidities in, and suggested that - in the so-called phase 4 clinical trials, that post-marketing surveillance stage - we should make a better effort to include patients with comorbidity and to look very carefully at the outcomes. Not just the effectiveness, but also the safety and tolerability. So I think those are the important steps forward.