Global gaps in MS diagnostic testing risk delaying diagnosis for many

A new global study published in Neurology Clinical Practice led by MSIF and its collaborators has shed light on a critical issue in multiple sclerosis (MS) care: access to the tests needed to diagnose the condition early.

Over the past two decades, revisions to MS diagnostic criteria (including the recently updated 2024 McDonald criteria), have made it possible to diagnose MS earlier than ever before. Earlier diagnosis allows people to access support and treatment sooner, helping to delay disability, improve long-term outcomes, and better manage their condition. However, access to key diagnostic tests used in MS diagnosis varies widely, with all ten tests assessed in this study available in just 41% of countries globally.

 “Updates to diagnostic criteria mean we can diagnose MS earlier than ever before, but without equal access to the tests needed, these changes won’t benefit everyone.” Rachel King, Senior International Evidence Manager at MSIF and lead for the Atlas of MS

What were the main findings?

The study collected data from 122 countries through the Atlas of MS.

The survey was conducted in 2024, before the publication of the updated McDonald criteria. It provides a baseline picture of global access to a range of diagnostic tests used in MS, including established and newer approaches. As the criteria had not yet been finalised at the time of the survey, it does not capture all of the imaging features, technical specifications, or biomarkers introduced in the latest revisions.

The results showed that access to the tests used for MS diagnosis varies widely:

• No single test is available in every country
• All ten key diagnostic tests are available in only 41% of countries
• Some countries reported no availability of these tests at all

Even where tests are available, this does not mean they are accessible to people or used in routine practice. Access is often limited by:

• Cost
• Lack of trained specialists to perform or interpret tests
• Limited awareness of their importance in diagnosis

These barriers were most common in low- and lower-middle-income countries but were also reported in high-income settings. Even in well-resourced health systems, factors such as reimbursement policies, long waiting times, or limited specialist capacity can delay access to appropriate testing.

It is also important to note that not every test is required when a person is being assessed for MS. Diagnosis is based on a combination of clinical symptoms and selected tests, depending on individual circumstances. However, having a range of tests available increases the likelihood of early diagnosis.

Why does this matter?

Early diagnosis of MS is essential. It allows people to start treatment sooner, which can reduce relapses, delay disability, and improve long-term outcomes.

Diagnosis also means recognition. For many people, it provides validation and an explanation for their symptoms. At a system level, diagnosis ensures people with MS are visible – counted in data, included in planning, and supported through health and social care systems. Without this, MS can remain hidden and the true scale of need underestimated.

Global data from the Atlas of MS has shown that barriers to diagnosis exist at every stage of the patient journey – from recognising symptoms to accessing specialists and diagnostic tests.

This study adds an important piece of the puzzle. It shows that even when diagnostic criteria improve, people cannot benefit unless the necessary tests are accessible, affordable, and used in practice.

The 2024 McDonald criteria introduce new ways to diagnose MS earlier, including increased use of MRI, cerebrospinal fluid (CSF) testing, optical coherence tomography (OCT), and evoked potentials. You can learn more about these tests in our explainer videos. These advances offer real promise, but they rely on access to specialised tests and expertise that are not yet equitably available worldwide. Without this, there is a risk that the benefits of earlier and more accurate diagnosis will not be realised for everyone.

What needs to change?

The findings highlight an urgent need for action to ensure that advances in MS diagnosis translate into real-world impact.

This includes:

• Improving access to diagnostic tests, including MRI and laboratory testing
• Reducing the cost of testing, particularly in low-resource settings
• Building expertise, so healthcare professionals can perform and interpret tests
• Raising awareness, especially as new diagnostic criteria are introduced

MSIF and our partners have already developed recommendations to address these challenges, including strengthening health systems and improving training and access to technology. These are outlined in the Improving diagnosis recommendations report.

As MS diagnosis becomes more advanced and specialised, ensuring global access to testing and expertise becomes even more important. Without targeted investment and education, there is a risk that existing inequalities could widen.

At the same time, there are also emerging opportunities. The 2024 McDonald criteria introduce multiple pathways to diagnosis, meaning not all tests are required in every case. This flexibility may help support earlier diagnosis in a wider range of settings, although diagnosing MS still relies on careful interpretation of different types of evidence, particularly where findings are not typical for MS.

For example, the criteria now allow evidence from the optic nerve to be used as part of the diagnosis. This may help MS be identified sooner in some cases. Optical coherence tomography (OCT) is one example of this in practice – a quick, non-invasive eye scan that can detect damage to the optic nerve and is relatively easy to perform.

Another example is kappa free light chains (kFLC), a laboratory test that can detect inflammation in the fluid around the brain and spine. Compared with some existing tests, it can be easier to interpret and may be lower cost in some settings, potentially reducing the need for highly specialised laboratory expertise.

Updates to MRI-based criteria may also allow diagnosis to be made using fewer scans or without contrast agents in some cases, helping to lower costs and simplify the diagnostic process in some settings.

“We’ve made significant progress in how we diagnose MS, with the latest criteria offering new opportunities for earlier and more accurate diagnosis. However our findings show that access to the tests underpinning these advances is far from equal. Addressing gaps in cost, expertise and availability must now be a global priority. With targeted action and advocacy, we have a real opportunity to ensure that these scientific advances translate into earlier diagnosis and better outcomes for people with MS, wherever they live.” Professor Andrew Solomon, University of Vermont, lead author of the study.

Turning evidence into impact: a global opportunity for advocacy

This study provides an important baseline for understanding global access to diagnostic testing in MS as the 2024 McDonald criteria begin to be implemented.

By highlighting these gaps, the study provides evidence that can support national and global efforts to improve access to diagnosis and care.

For the global MS community, these findings provide clear evidence to support advocacy efforts.

They reinforce the need for:

• Investment in diagnostic infrastructure
• Training and education for healthcare professionals
• Policies that ensure equitable access to essential tests

They also highlight the importance of integrating diagnostic access into broader conversations about MS care and health system strengthening.

With the right investment, education, and advocacy, there is a clear opportunity to ensure that advances in MS diagnosis benefit people everywhere.

Further information

• Access the published article in Neurology Clinical Practice: INSERT DOI and LINK TO JOURNAL
• Access the accepted manuscript version of the publication (peer-reviewed author manuscript, free to access): INSERT LINK TO ACCEPTED MANUSCRIPT VERSION ON MSIF WEBSITE. Please note that this version is the accepted manuscript following peer review. It contains the same core findings as the published article, but may differ slightly in formatting, copy-editing and typesetting. The journal article linked above is the final published version of record.
• Evidence is a powerful tool for advocacy. Across the global MS movement, organisations are using data to influence decision-makers and improve access to diagnosis, treatment and care. Explore examples of advocacy in action and learn from experiences across the MS community here.