Neurological disease treatment is very costly. It is often is not as efficient as it can be. You have advanced the concept of "Stratified Medicine" to improve quality of clinical care for patients with neurological disease. Dr. Anton Titov, MD. What is Stratified Medicine concept? How does it help in clinical treatment of neurological diseases, including multiple sclerosis? The concept of stratified medicine is that all patients are not similar. Dr. Paul M. Matthews, MD. Some groups of patients who carry a common diagnosis may behave in a more similar fashion to each other than they do to the group as a whole. There are distinct subgroups of patients with similar disease characteristics within a larger umbrella diagnostic group as a whole. In the context of multiple sclerosis it is a particularly important idea. Dr. Anton Titov, MD. Because multiple sclerosis itself is a syndrome. It is not a specific diagnosis established on the basis of a very precisely recognized common disease-causative factor. The importance of stratified medicine in disease in general is this. Dr. Paul M. Matthews, MD. Patients with different forms of expression of a syndrome or disease may behave differently with respect to treatments. Patients may also have different prognosis and results of treatment. Being able to express the difference in results of treatment is important. Patients must balance the benefits and risks of treatment or no treatment. Every patient belongs to such distinct subgroup with similar characteristics of clinical course and prognosis. Dr. Paul M. Matthews, MD. Several subgroups form a larger group within a given disease entity. Understanding the subgroup an individual belongs to is important in guiding therapy for other reasons too. Here is a specific example of Stratified Medicine in the context of multiple sclerosis. Dr. Paul M. Matthews, MD. We know that there exists a small group of patients with multiple sclerosis. They may not show very rapid progression of multiple sclerosis at all. This is true even we do not treat them. Then there is another group of patients with multiple sclerosis. It is also relatively small. It will show very malignant progression of multiple sclerosis. Dr. Paul M. Matthews, MD. Finally, there are many patients with multiple sclerosis who belong to a middle group. After initial diagnosis of multiple sclerosis, we can assign patients to appropriate subgroup. This helps to inform clinical decisions regarding initial treatment of multiple sclerosis. This helps patients to make the decision whether to start treatment or not immediately. Dr. Anton Titov, MD. Assignment to distinct clinical group helps to make the choice of first treatment. Dr. Paul M. Matthews, MD. We can use a traditional first-line medication for multiple sclerosis. Or we can use medications with a higher efficacy but also with a higher risk profile. All can be informed by that initial decision to assigned a patient to a specific clinical group. This is Stratified Medicine concept. Personalized Medicine is taking Stratified Medicine one step further. Stratified Medicine tells us about the following classification of patients. “This class of patients with a given diagnosis are more similar. Dr. Paul M. Matthews, MD. We can have these general expectations for behavior of disease in that group of patients”. Personalized Medicine is about trying to individualize this understanding of disease course and prognosis more precisely. Precision medicine helps us to understand how a single given patient is responding or not responding to medication or to a treatment protocol. Dr. Anton Titov, MD. Precision medicine helps us to identify medication that would be most appropriate for that person individually. Here is the best way we can use today a Stratified Medicine and Precision Medicine for patients with multiple sclerosis. We can carefully observe patients on-treatment or off-treatment. Dr. Paul M. Matthews, MD. We can follow patients serially with clinical measures of relapse rate and disability progression of multiple sclerosis. We can use MRI imaging to measure multiple sclerosis activity. We can follow, for example, T2 hyperintense lesion count. We can identify brain volume change on MRI. Dr. Paul M. Matthews, MD. We can assess patients who have evidence for no multiple sclerosis disease progression. We can identify patients who have evidence for modest disease activity in multiple sclerosis. We can also find those patients who have evidence for higher multiple sclerosis disease activity. That is how we can change whatever our initial treatment structure is. Dr. Paul M. Matthews, MD. We can adjust and tailor treatment protocols to individual patients. Treatment becomes most appropriate for that individual patient with multiple sclerosis. Dr. Anton Titov, MD. That is stratified medicine. It is identifying groups of patients with similar disease characteristics and prognosis. Personalized medicine is trying to individualize treatment for a single person with multiple sclerosis.