BACKGROUND:The 2024 revision of the McDonald diagnostic criteria for multiple sclerosis (MS) incorporate novel biomarkers and topographies to enhance MS diagnostic sensitivity and specificity. Whether these changes improve diagnostic yield in clinical practice remains to be determined, particularly in regions with limited access to advanced investigations.
OBJECTIVES:To evaluate the diagnostic yield and agreement between the 2017 and 2024 McDonald criteria in an Egyptian MS cohort.
METHODS:In this cross-sectional study, 197 consecutive patients presenting with suspected demyelinating disease were classified according to both the 2017 and 2024 McDonald criteria. The proportion of MS diagnoses, inter-criteria agreement (Cohen's κ), and discordance (McNemar's test) were assessed overall and within subgroups (age, clinical presentation, MRI lesion topography).
RESULTS:The 2017 criteria identified 168 MS cases, whereas the 2024 criteria identified 195, diagnosing 27 additional patients (+13.7 %). Agreement was low (κ = 0.112), with McNemar's test confirming significant discordance (p < 0.001). Subgroup analyses showed additional cases mainly in patients <50 years (+27 cases, κ = 0.111, p < 0.001) and in those with typical presentations (+26 cases, κ = 0.116, p < 0.001). No differences were observed in patients ≥50 years or with atypical presentations (κ = 1.0, complete concordance). By MRI topography, the largest gain occurred in patients with 4-5 topographies (+27 cases, κ = 0.111, p < 0.001). Key contributors included four topographies without DIT (74.1 %) and optic nerve inclusion (51.9 %).
CONCLUSION:The 2024 McDonald criteria substantially increase MS diagnostic yield, especially in younger patients, typical clinical presentations, and those with limited MRI lesion burden, but demonstrate low concordance with the 2017 version. These findings support their application in clinical practice, while highlighting the need for prospective validation and careful interpretation in atypical or older patients.