by Sharon Roman[i]

Little is known about disease-modifying drug (DMD) use by immigrants with multiple sclerosis (MS) in countries with universal health coverage. A recent call-to-action has highlighted the need for a better understanding of potential health disparities among immigrants, and the role of non-medical factors, and subsequent inequities in MS care, that may form the basis of those disparities. While barriers to healthcare, including cultural and financial, often disproportionately affect immigrants, much remains unknown about healthcare use by immigrants, such as access to, and use of a DMD to treat MS. Canada’s long history of immigration, combined with its universal healthcare coverage and high rate of MS makes it an ideal region to study healthcare use in immigrants with MS.

MS is a life-altering, chronic immune-mediated disease of the brain and spinal cord; most people are diagnosed between the ages of 20 and 50. It is the most common cause of non-traumatic neurologic disability in young adults. While there is no cure, MS is now a treatable disease, with over 20 different DMDs approved for use. Yet key gaps in knowledge surrounding access to these DMDs by immigrants remain.

Using administrative healthcare data spanning the entire province of British Columbia, Canada over a 16-year period, researchers identified people with MS. Those with MS included were aged 18 and over, had lived in the province for at least 1-year prior to, and at least 5-years after MS onset. The researchers investigated the relationship between immigration status and use of a DMD within 5-years of MS onset. Further, they explored whether socioeconomic status (SES) impacted DMD use for the immigrants and long-term residents. SES was found using information from Statistics Canada linking a person’s postal code to their neighbourhood income level and dividing those into 5 equal ‘quintiles.’

Odds of filling a DMD prescription lower in immigrants of lower socioeconomic status

Of the 8,762 people with MS, 6% (522) were immigrants; women outnumbered men similarly in both groups. Most immigrants had lived in Asia (41%) and Europe (34%) before moving to Canada; 13% were refugees. More immigrants fell within the least affluent quintile (23%) at MS onset than long-term residents (18%). More than three-quarters of immigrants (76%) and long-term residents (77%) did not have a co-existing condition at MS onset.  When comparing to those of comparable sex, age, co-existing conditions, SES, and date of MS onset, the odds of filling a DMD prescription within 5-years after MS onset were similar between immigrants and long-term residents with MS (26% and 23% respectively).

In contrast, when examining whether socioeconomic status and immigration status had an impact on use of a DMD, the researchers found a 17% decrease in the odds of filling a DMD prescription within 5-years of MS onset for each decrease in neighbourhood-level income (quintile) for immigrants, but not for long-term residents. At the least affluent quintile, the odds of an immigrant filling a prescription for a DMD was 32% lower than long-term residents of the same neighbourhood-level income.

Immigration and socioeconomic status contribute to disparities in DMD use

Lower socioeconomic status has been associated with higher rates of co-existing health conditions, and higher mortality rates in both the MS and general population. Even in regions with universal healthcare coverage such as Canada, health disparities persist in lower socioeconomic groups.

This real-world population-based study in a universal healthcare setting found the use of any DMD to treat MS within 5-years of MS onset differed between immigrants and long-term residents—socioeconomic status impacted use. Immigrants (but not long-term residents) in the lowest neighbourhood-level income were less likely to fill a DMD prescription, suggesting that intersectionality (how systems of inequality intersect) of immigrant status and socioeconomic status contributes to disparities in DMD use. Immigrants (but not long-term residents) living in lower (versus higher) income neighborhoods may face health disparities, at least when it comes to prompt use of a DMD to treat MS. A better understanding of how this affects long-term health for immigrants with MS, and what factors may drive potential health disparities for this group is needed.

[i] Vancouver, BC, Canada

Twitter: @SRoman_SPQR

Graf, J., Ng, H.S., Zhu, F. et al. Multiple sclerosis disease-modifying drug use by immigrants: a real-world study. Sci Rep 13, 21235 (2023). https://doi.org/10.1038/s41598-023-46313-7

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