Real-life evaluation of the 2017 McDonald criteria for relapsing-remitting multiple sclerosis after a clinically isolated syndrome confirms a gain in time-to-diagnosis.

Background: Previous cohort studies evaluating the performances of the McDonald criteria suffered from bias regarding real-life conditions. We aimed to evaluate the probability of diagnosing relapsing-remitting multiple sclerosis (MS) at several timepoints from the first medical evaluation and the gain in time-to-diagnosis with the 2017 McDonald criteria compared with the 2001, 2005 and 2010 versions in real life.

Methods: Patients with a first demyelinating event suggestive of MS between 2002 and 2020 were included in the ReLSEP, an exhaustive and prospectively incremented registry of MS patients in North-Eastern France. We estimated the probability of being positive at the first medical evaluation and at five timepoints according to the four versions of criteria using Kaplan-Meier estimators and Cox models.

Results: A total of 2220 patients were followed up for a median of 7.1 years. At baseline, 31.7%, 32.1%, 36.6% and 54.0% of patients, respectively, fulfilled the 2001, 2005, 2010 and 2017 McDonald criteria. Using the 2017 criteria, the gain in time-to-diagnosis was 3.7 months compared with the 2010 criteria. The presence of intrathecal synthesis of immunoglobulin G in the McDonald 2017 criteria led to a 1.8-month reduction in median time-to-diagnosis compared to a version of McDonald 2017 without this criteria.

Conclusions: In real-life, the 2017 McDonald criteria revision undoubtedly shortened time-to-diagnosis.