Population-based study of “no evident disease activity” in MS

Objective To determine the persistence of no evident disease activity (NEDA) in a population-based relapsing-remitting MS (RRMS) cohort. Methods All incident cases of RRMS in Olmsted County between 2000 and 2011 were identified using a medical records linkage system. Persistence of NEDA after RRMS diagnosis was determined by retrospective chart review. MRI activity, relapse, or Expanded Disability Status Scale (EDSS) worsening resulted in failure of NEDA. Results We identified 93 incident cases of RRMS including 82 individuals with sufficient follow-up to determine the persistence of NEDA. There were 44 individuals not on disease-modifying therapy (DMT), whereas 37 individuals were prescribed an injectable DMT and 1 received mitoxantrone during the interval over which NEDA was maintained. NEDA was maintained by 63% at 1 year, 38% at 2 years, 19% at 5 years, and 12% at 10 years according to routine care assessment. At 10 years, there was no difference in EDSS disability among patients who maintained NEDA vs those who failed NEDA at 1 year ( p = 0.3). Conclusions NEDA infrequently persists beyond 2 years in a population-based cohort of newly diagnosed patients with RRMS.