Performance of the 2024 McDonald diagnostic criteria for multiple sclerosis

BACKGROUND: Diagnostic criteria for multiple sclerosis (MS) have undergone numerous revisions, the latest announced in 2024. OBJECTIVES: This study compared the 2024 McDonald criteria with earlier iterations regarding sensitivity, time to MS diagnosis, and disability. Patients with clinically or radiologically isolated syndrome (CIS, RIS) between 2013 and 2022, aged 18-50, visited within 6 months, and with brain MRI were included. The primary outcome was MS diagnosis according to 2024 versus 2017 criteria. Secondary outcomes included time to diagnosis and disability by Multiple Sclerosis Severity Score. Outcomes were stratified into pre-2017 and 2017-2022 cohorts, with 2010 criteria applied to the pre-2017 group. Finally, 2024 criteria were prospectively tested. RESULTS: Among 163 patients (mean age 31.4; 72% female), for the 2024 criteria, diagnosis sensitivity was 81.4% versus 74.9% for 2017 criteria; in the pre-2017 cohort, 49.4% for 2010 criteria. Median time to diagnosis was shorter with 2024 criteria (2.0 [IQR 1.1-4.2] months) compared to 2017 and 2010 criteria (2.1 [1.2-4.7] and 3.8 [1.5-11.2], respectively). Patients fulfilling 2024 and 2017 criteria at baseline showed lower MSSS during follow-up than those meeting 2010 criteria. Prospectively, 11/13 (85%) fulfilled 2024 criteria at baseline. CONCLUSIONS: The 2024 McDonald criteria increased sensitivity, shortened time to diagnosis, and identified patients with milder disease course.