Background: Therapeutic inertia (TI) in multiple sclerosis (MS) is defined as the lack of treatment escalation when there is evidence of disease activity. Limited information is available on physician-related factors influencing TI in MS. The aim of the study was to evaluate whether physicians’ risk preferences are associated with TI in the management of MS by applying concepts from behavioral economics. Methods: A study with neurologists managing patients with MS was conducted in Spain. Participants answered questions regarding the management of 20 case-scenarios and completed three surveys and four experimental paradigms based on behavioral economics. Surveys and experiments included standardized tests to measure aversion to risk and ambiguity, physicians’ reactions to uncertainty, and questions related to risk preferences in different domains. Results: Of 161 neurologists who were invited, 136 agreed to participate, and 96 completed the survey (response rate: 60%). TI was present in 68.8% of participants. Total aversion to ambiguity and low tolerance to uncertainty were observed in 22.9% and 42.7% of participants, respectively. Aversion to ambiguity was associated with a higher prevalence of TI (86.4% with aversion to ambiguity vs. 63.5% without aversion to ambiguity; p=0.042). In multivariate analyses, aversion to ambiguity was the strongest predictor of TI (OR 7.39; 95%CI 1.40-38.9), followed by low tolerance to uncertainty (OR 3.47; 95%CI 1.18-10.2). TI was less common among neurologists with greater volumes of patients per week as well as among MS specialists. Conclusion: Therapeutic inertia is a common phenomenon affecting nearly 7 out of 10 neurologists caring for MS patients. Behavioral economics is an innovative approach that may help our understanding of decision making in MS.

Background Multiple sclerosis patients who discontinue using natalizumab are at risk of a rebound in disease activity. However, the optimal alternative therapy is not currently known. Aims of the study We report on clinical and MRI data and patient safety in a group of relapsing–remitting multiple sclerosis patients who tested seropositive for the JC virus and who have switched from natalizumab to fingolimod because of concerns regarding PML risks. Methods The test for JC virus antibodies was performed in 18 relapsing–remitting multiple sclerosis patients who were being treated with natalizumab for more than 1 year. Eight seropositive patients switched to fingolimod while the seronegative patients continued with natalizumab. Results After switching to fingolimod, five of eight patients (63%) experienced clinical relapses, and MRI activity was detected in six of eight patients (75%). Neither clinical relapses nor MRI activity was observed in the patients who continued with natalizumab. No serious adverse effects were detected. Conclusions Natalizumab is an effective treatment for relapsing–remitting multiple sclerosis, but its discontinuation continues to be a complex problem. All of the therapies tried thus far, including fingolimod, have been unable to control the reactivation of the disease. Further studies addressing alternative therapies after natalizumab discontinuation are necessary.