The use of natalizumab in multiple sclerosis has been restricted by the risk of progressive multifocal leukoencephalopathy (PML). JC virus carriership, duration of natalizumab treatment and past immunosuppression are known risk factors. This has allowed for calculated risk assessment for individual patients to be implemented. Not much data are available about the effect of JCV carriership on patient willingness to continue natalizumab. Here, we evaluated the impact of JCV seropositivity on safety feelings, anxiety and treatment continuation for patients treated with natalizumab, using a visual analog scale, the Hospital Anxiety and Depression Scale and a decisional conflict scale. Seropositivity led to an elevated anxiety level for PML (p = 0.004). However, so far only 3% of patients have discontinued natalizumab because of JCV positivity in our cohort.
Keywords: JC virus; Multiple sclerosis; natalizumab; progressive multifocal leukoencephalopathy.