Background: Multifocal progressive leukoencephalopathy (PML) is associated with JC virus (JCV) seropositivity, past immunosuppression, and natalizumab treatment for two years or more.
Aim: The aim of this study was to investigate the rate of treatment discontinuation after stratifying for the three risk factors in a group of 104 natalizumab-treated patients with relapsing-remitting multiple sclerosis.
Methods: The investigators investigated JCV serological status in their population. We then divided patients into groups according to their PML risk. Treatment indication was reassessed. Of the patients, 64 (61.5%) were JCV seropositive. Amongst seropositive patients on natalizumab for 2 years or more, 10 had received immunosuppression (group A), and 38 had not (group B).
Results: After an informed and shared decision-making process, 6/10 (60%) from group A compared with 9/38 (23.7%) from group B discontinued treatment (p=0.027). In groups A and B, discontinuation also depended upon doctors’ views (p=0.019, group A; p=0.010, group B) and clinical outcomes (p=0.021, group A). No-one from low-intermediate risk groups discontinued.
Conclusions: The decision to discontinue natalizumab treatment is complex, even when clear PML risk rates are described. Clinical outcomes and doctors’ idiosyncrasies play a crucial part in patients’ final choice.