Global Access to Diagnostic Paraclinical Testing Incorporated in the 2024 Revised McDonald Criteria: Disparities and...

Paraclinical testing incorporated within multiple sclerosis (MS) diagnostic criteria over time have facilitated earlier diagnosis, yet global implementation is largely unknown. Lack of "specialist medical equipment or diagnostic tests" was a barrier to early diagnosis of MS endorsed by a third of 107 countries surveyed in the recent Multiple Sclerosis International Federation Atlas of MS Third Edition. This study assessed global access to paraclinical testing incorporated in MS diagnostic criteria.

Survey development included stakeholders with varied expertise and perspectives from all World Health Organization regions and World Bank (WB) country economy income categories. The survey assessed availability, routine use, and barriers to routine use of MRI, CSF testing, evoked potentials, optical coherence tomography, and serum aquaporin-4 immunoglobulin G and myelin oligodendrocyte glycoprotein immunoglobulin G antibody testing. Opinions regarding anticipated 2024 criteria revisions and preferences regarding the dissemination of MS guidelines were surveyed. The survey was available from April 11, 2024, to September 2, 2024.

One hundred twenty-two of 149 (82%) of country coordinators participated. No paraclinical test was available across all countries. All 10 tests were available in only 41% of countries. Availability of paraclinical testing did not guarantee routine use in the diagnostic evaluation for MS. Cost and lack of expertise for performance or interpretation were frequent barriers to routine use. Such barriers were present even in WB high-income countries, but low- and low-middle-income countries reported significantly more limited availability of paraclinical testing and significantly diminished routine use to aid diagnosis of MS.

This study highlights worldwide barriers and disparities in access to paraclinical testing that can expedite the diagnosis of MS. Creative approaches are urgently needed to address cost and required expertise for these paraclinical tests to improve worldwide access. Our data suggest that targeted educational efforts surrounding 2024 McDonald criteria revisions can reduce barriers to implementation. There was enthusiasm that the incorporation of these new approaches to paraclinical testing within the criteria would improve access to early MS diagnosis. This study will provide valuable baseline data to inform future assessments of global access to paraclinical testing for the diagnosis MS.