Canadian MG patients report better quality of life than US patients

People with myasthenia gravis (MG) in a Canadian patient group reported better quality of life than those in a U.S. group, even though their experiences getting diagnosed were broadly similar, a study found.

The differences remained statistically significant after researchers accounted for patients’ age, sex, and disease severity. These findings “raise the possibility that broader clinical, social, and system-level factors may influence patient outcomes beyond diagnostic timing alone,” the researchers wrote.

The study, “Myasthenia gravis in Canada and the United States: cross-national comparison of diagnostics and quality of life,” was published in the journal BMC Neurology.

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Comparing MG diagnosis in Canada and the US

MG is a chronic autoimmune disease marked by fluctuating muscle weakness and fatigue. Because its symptoms can resemble those of other conditions, MG can take longer to diagnose. Studies have linked longer delays in diagnosis to a greater burden from the disease.

Although MG can affect quality of life, most previous research has focused on patients in a single country. “As a result, there remains a limited understanding of how the healthcare system context may influence patient-reported experiences and outcomes across different care environments,” the researchers wrote.

To explore these differences, researchers in Canada compared the time it took patients with MG to get diagnosed and their quality of life in the two countries. In Canada’s publicly funded healthcare system, primary care doctors usually refer patients to specialists. In the U.S., access to specialists depends more heavily on insurance coverage and out-of-pocket costs.

The researchers analyzed previously collected data from 32 Canadian patients (median age, 40; 75% women) and 679 U.S. patients (median age, 49; 73% women). All were participants in the MyRealWorld MG registry, an international study assessing the impact of MG on patients’ lives.

On average, Canadian patients waited 1.2 years from their first symptoms to their first medical visit, compared with 1.86 years for U.S. patients. From that first visit to a confirmed diagnosis, the average time was 1.17 years in Canada and 1.32 years in the U.S. Overall, the average time from the first symptoms to diagnosis was 2.37 years in Canada and 3.18 years in the U.S.

Although the average times were longer in the U.S., none of these differences was statistically significant, meaning chance could explain them.

Patients also saw a similar number of specialists before diagnosis, averaging 2.28 in Canada and 2.41 in the U.S.

Diagnostic testing patterns largely similar in both countries

Testing patterns were also generally comparable. All 30 Canadian patients with available testing data (100%) underwent blood tests for antibodies associated with MG, compared with 91% of 656 U.S. patients with those data. Nerve function tests were also more common among Canadian patients than U.S. patients (77% vs. 58%), although the difference approached but did not reach statistical significance.

CT or MRI scans were used in 66% of Canadian patients and 58% of U.S. patients. Similar proportions of Canadian and U.S. patients underwent the edrophonium test (13% vs. 10%). This older test involves giving a short-acting drug to see whether muscle weakness temporarily improves.

“The United States had greater mean diagnostic duration across all three defined time intervals while Canadian patients received higher proportions of diagnostic testing across the four types of tests,” the team wrote. “While these differences were not statistically significant and should not be interpreted as evidence of an effect of system-level factors, they may offer possible context for the cross-country differences observed.”

Neurologists diagnosed 62.5% of Canadian patients and 76% of U.S. patients, while primary care doctors made the diagnosis in 15.6% of Canadian patients and 8.9% of U.S. patients. Neither difference was statistically significant. The researchers noted that the patterns in both countries were broadly consistent with their respective healthcare systems, with greater reliance on primary care referrals in Canada and more direct access to specialists in the U.S.

However, the results differed when researchers examined patients’ self-reported quality of life. On the Myasthenia Gravis Quality of Life 15-item revised scale (MG-QOL-15r), which measures how MG affects daily life, Canadian patients had an average score of 10.3, compared with 15.4 for U.S. patients. Higher scores indicate worse quality of life.

After accounting for age, sex, and disease severity, U.S. patients still scored an average of 5.24 points higher than Canadian patients, a statistically significant difference “corresponding to a moderate to large effect size,” the researchers wrote.

Quality-of-life differences persist after adjustments

A similar pattern emerged on a broader measure of health-related quality of life, called the EuroQol 5-dimension 5-level instrument (EQ-5D-5L). Unlike the MG-specific measure, this tool assesses overall health, including mobility, daily activities, pain, and emotional well-being. Higher scores indicate better quality of life. Canadian patients had an average score of 0.74, compared with 0.61 for U.S. patients. The difference was statistically significant and remained so after researchers accounted for age, sex, and disease severity.

The findings suggest that factors beyond the time it takes to diagnose MG may play a role in patients’ quality of life. They raise “the possibility that long-term quality of life outcomes in myasthenia gravis are not only influenced by diagnostic delay but might also be influenced by a combination of clinical, sociodemographic, and system-level factors,” the researchers wrote.

However, the researchers cautioned that the small Canadian sample and the large difference in group sizes “limited the statistical power to detect between-country differences in diagnostic practices, testing patterns, and provider type, particularly for small-to-moderate effects.”

Larger studies are needed to better understand which factors may be linked to these quality-of-life differences, “which may help inform future strategies to improve MG management and quality of life,” the researchers concluded.