Characteristics of a population-based multiple sclerosis cohort treated with disease-modifying drugs in a universal healthcare setting

ABSTRACT

Background: Relatively little is known about the use of disease-modifying drugs (DMDs) for multiple sclerosis (MS) in the population-based universal healthcare setting. This study aimed to describe the characteristics of a population-based cohort with MS and their DMD exposure in four Canadian provinces.

Methods: We identified all adults (aged ≥18 years) with MS using linked population-based health administrative data. Individuals were followed from the most recent of their first MS or demyelinating event or 1 January 1996(study entry), to the earliest of death, emigration, or 31 March 2018(study end). Cohort characteristics examined included sex, age, socioeconomic status, and comorbidity burden.

Results: Overall, 10,418/35,894 (29%) of MS cases filled a DMD prescription during the 22-year study period. Most were women (n = 7,683/10,418;74%), and 17% (n = 1,745/10,418) had some comorbidity (Charlson Comorbidity Index≥1) at study entry. Nearly 20% (n = 1,745/10,418) were aged ≥50 when filling their first DMD; the mean age was 39.6 years.

Conclusions: Almost 1 in 6 people with MS had at least some comorbidity, and nearly 1 in 6 were ≥50 years old at the time of their first DMD. As these individuals are typically excluded from clinical trials, findings illustrate the need to understand the harms and benefits of DMD use in these understudied groups.

KEYWORDS:

• Canada
• cohort studies
• disease-modifying drugs
• health administrative data
• multiple sclerosis
• population-based

Acknowledgments

We are grateful to the Data Services Platform of the Saskatchewan Centre for Patient-Oriented Research (SCPOR). We are also grateful to Yan Wang (Dalhousie University) for her support in performing data analyses in Nova Scotia. Access to, and use of, BC data was facilitated by Population Data BC, and approved by the BC Ministry of Health, BC PharmaNet, and the BC Vital Statistics Agency. The authors acknowledge the Manitoba Centre for Health Policy for use of the Population Research Data Repository under project #2018-023 (HIPC #2018/19-13). Some data used in this report were made available by Health Data Nova Scotia of Dalhousie University. All inferences, opinions, and conclusions drawn in this manuscript are those of the authors, and do not reflect the opinions or policies of the British Columbia Data Steward(s), Manitoba Centre for Health Policy or Manitoba Health, Health Data Nova Scotia or the Nova Scotia Department of Health and Wellness. This study is based, in part, on de-identified data provided by the Saskatchewan Ministry of Health and eHealth Saskatchewan. The interpretation and conclusions contained herein do not necessarily represent those of the Government of Saskatchewan, the Saskatchewan Ministry of Health, or eHealth Saskatchewan.

Author contributions

Huah Shin Ng and Helen Tremlett conceptualized and designed the study, interpreted the results, and drafted the manuscript. Huah Shin Ng, Feng Zhu, Shenzhen Yao and Okechukwu Ekuma performed data analysis. Feng Zhu, Elaine Kingwell, Yinshan Zhao, Lawrence W Svenson, Charity Evans, John D. Fisk, Ruth Ann Marrie, Helen Tremlett facilitated obtaining funding (PI: Tremlett, CIHR Project and Foundation award). All authors contributed to the design of the study, revised the manuscript critically for intellectual content, approved the final version to be published, and agreed to be accountable for all aspects of the work.

Declaration of interest

HS Ng receives funding from the MS Society of Canada’s endMS Postdoctoral Fellowship, and the Michael Smith Foundation for Health Research Trainee Award. During the past year, HS Ng has received funding from the Canadian Institutes of Health Research (CIHR) Drug Safety and Effectiveness Cross-Disciplinary Training Program. E Kingwell is supported through research grants from the MS Society of Canada and the Canadian Institutes of Health Research. During the past 5 years, E Kingwell has received travel expenses to attend conferences from ACTRIMS (2018, 2020) and ECTRIMS (2019). C Evans receives research funding from CIHR and the Saskatchewan Health Research Foundation. J Fisk receives research funding from CIHR, the MS Society of Canada, Crohn’s and Colitis Canada, Nova Scotia Health Authority Research Fund, and licensing and distribution fees from MAPI Research Trust. RA Marrie receives research funding from: CIHR, Research Manitoba, Multiple Sclerosis Society of Canada, Multiple Sclerosis Scientific Foundation, Crohn’s and Colitis Canada, National Multiple Sclerosis Society, CMSC, and the US Department of Defense. She is supported by the Waugh Family Chair in Multiple Sclerosis. H Tremlett is the Canada Research Chair for Neuroepidemiology and Multiple Sclerosis. Current research support received from the National Multiple Sclerosis Society, the Canadian Institutes of Health Research, the Multiple Sclerosis Society of Canada and the Multiple Sclerosis Scientific Research Foundation. In addition, in the last five years, has received research support from the UK MS Trust; travel expenses to present at CME conferences from the Consortium of MS Centres (2018), the National MS Society (2016, 2018), ECTRIMS/ACTRIMS (2015, 2016, 2017, 2018, 2019, 2020), American Academy of Neurology (2015, 2016, 2019). Speaker honoraria are either declined or donated to an MS charity or to an unrestricted grant for use by HT’s research group. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial relationships or otherwise to disclose.

Additional information

Funding

This work was supported by the Canadian Institutes of Health Research (CIHR) under Project and Foundation Grant [PJT-156363 and FDN-159934, PI: Tremlett].