These factors provide insights to how progression varies between patients and point to possible directions for treatment. patients’ EDSS scores change at individually varying rates, with a trend to gradually accumulate disability over the years.Ī critical question for MS researchers is identifying the prognostic factors that influence EDSS progression. In addition, similar to many other neuroinflammatory and neurodegenerative diseases, MS is heterogeneous, i.e. To understand better how the accumulation of disability is related to demographic and disease related variables, modeling of how the progression of EDSS varies from subject -to- subject, for example remains unchanged, increases (disease worsening) or decreases (disease improvement), is of interest. As part of clinical trials, the EDSS score is an ordinal outcome measured approximately every 4 - 6 months as a part of clinical trials in relapsing and progressive MS patients. Progression of the disease over time causes increasing disability, which is measured on the expanded disability status scale (EDSS) ( Kurtzke ), measuring several aspects of disability (such as walking) and indicating functioning ability of an individual, ranging between 0 (normal neurological examination) to 10 (death). Multiple sclerosis (MS) is a chronic neuroinflammatory and neurodegenerative disease that affects the central nervous system.