Disease-modifying therapies for nonrelapsing multiple sclerosis Absence of evidence does not constitute evidence of absence

The lack of clinical trialdata demonstrating efficacy of disease-modifying treatments (DMTs) for nonrelapsing forms of multiple sclerosis (MS) does not prove that DMTs are ineffective for nonrelapsing MS. It has been argued that DMTs have met primary endpoints in relapsing MS, but not in nonrelapsing forms of the disease. This does not prove that such treatments are ineffective for nonrelapsing phenotypes. It could mean that clinical trialendpoints are ineffective in identifying true differences between treatment and placebo arms, or do not properly account for individual variation within clinical trialcohorts.