“…The severity of MS might differ within patient groups which add to differences of resource utilization making healthcare costs skewed [75]. Age, disability (EDSS), and presence of depression have been found to be independent predictors of costs in univariate analyses [59]. Furthermore, differences between studies as regards the proportion of patients with MS relapses of severity, as well as duration of relapses, are important for the estimated economic burden of MS [7], and differences in sampling of patients for inclusion COI studies may also be of importance for comparison between studies [50].…”