Prescription Drug Safety and Effectiveness in Multiple Sclerosis

Study population: A validated case definition of multiple sclerosis (MS) will be applied to the health administrative data to identify all MS patients in 5 Canadian provinces (British Columbia, Manitoba, Nova Scotia, Saskatchewan and Alberta; Studies 1,2,4-6). Developed in Manitoba, the positive predictive value was 80.5% and negative predictive value (NPV) was 75.5% among a population of persons with ≥1 claim for any demyelinating disease. The NPV would be \>99% at the general population level where more than 98% of individuals have no claims for demyelinating disease. The algorithm has been successfully applied in British Columbia, Nova Scotia and Saskatchewan. When MS-specific clinical data are used (British Columbia, Manitoba, Nova Scotia; Study 3), the diagnosis is neurologist confirmed, according to the prevailing international criteria. Study period: The earliest study start is Jan/1996 (the 1st full year that DMDs were available and the first year of available administrative and DMD-related data), and the latest study end is March 31, 2018; this represents \>2 decades of drug and patient-related follow-up. Study entry: Most recent of 1-Jan-1996, an individual's 18th birthday, date of 1st MS-related claim or date of 1st MS clinic visit (when clinical data are accessed \[Study 3\]). Study end: Earliest of death, emigration from the respective province, last MS clinic visit (when clinical data are accessed \[Study 3\]), or 31-December-2017 (British Columbia, Manitoba, Nova Scotia, Alberta) or 31-March-2018 (Saskatchewan). DMD exposure: DMD use, as identified using prescription data. An individual's exposure status can change over time and will be dynamically classified as: 1) no DMD, 2) any DMD, then by generation: 2a) any 1st or 2b) 2nd generation DMD. When possible, the individual drug classes will be explored (beta-interferon \[as one class\], glatiramer acetate, natalizumab, fingolimod, dimethyl fumarate, teriflunomide, alemtuzumab). Time perspective: Analyses of prospectively recorded health administrative, prescription and clinical data.