Changes in Fatigue and Cognition in Patients with Relapsing Forms of Multiple Sclerosis Treated with Natalizumab: The ENER-G Study

Fatigue and cognitive impairment are debilitating features of multiple sclerosis (MS). ENER-G was a 12-month, open-label, multicenter, single-arm observational study designed to evaluate changes in fatigue and cognition in MS patients treated with natalizumab. Adults with relapsing MS and initiating natalizumab were enrolled. The primary endpoint was change in Visual Analog Scale for Fatigue (VAS-F) score over 12 weeks. Changes in Modified Fatigue Impact Scale (MFIS) score, Fatigue Severity Scale (FSS) score, and cognitive performance, using Automated Neuropsychological Assessment Metrics (ANAM), were also assessed. Patients (N = 89) had a mean age of 41 years and a median Expanded Disability Status Scale score of 3.0, and 83% had used at least two prior MS therapies. Significant improvements were observed and maintained at 12 weeks in VAS-F (mean ± SD baseline score, 77.7 ± 10.2; mean ± SD change, −14.9 ± 17.1; P < .0001), MFIS (mean baseline score, 59.1 ± 12.2; mean change, −7.4 ± 11.8; P < .0001), and FSS (median baseline score, 6.3 [range, 3.9–7.0]; median change, −0.4 [range, −2.9–1.4]; P < .0001). Cognitive performance remained stable or improved (depending on the ANAM measure). Thus significant improvements in fatigue were maintained over time, and cognitive performance improved or remained stable up to 48 weeks after initiation of natalizumab in MS patients with some degree of fatigue.