Prescription drug dispensations 15 years before multiple sclerosis onset: A matched cohort study, British Columbia, Canada

Background: Few studies assessed drug dispensations for periods >5 years pre-multiple sclerosis (MS) onset or examined the time pre-MS symptom onset. Objective: The objective of this study was to examine prescription drug dispensations up to 15 years pre-MS symptom onset. Methods: Matched cohort study linking prescription, clinical and administrative data, 1996–2018. Results: Among 1243/6212 MS/non-MS persons, those with MS had higher dispensation rate ratios (RRs) pre-onset for systemic antibacterials up to 15 years (RR (range) = 1.15–1.30; q -values (range) = 0.11–0.31), airway drugs up to 8 years (RR (range) = 1.49–1.71; q -values (range) = 0.26–0.35), sex hormones (females only) up to 7 years (RR (range) = 1.19–1.46; q -values (range) = 0.26–0.39) and psychoanaleptics up to 6 years (RR (range) = 1.36–1.59; q -values (range) = 0.09–0.31), but lower beta-blockers (years 13–14 pre-onset, RRs = 0.10; q -values (range) = <0.00001–0.31). After multiple-comparison adjustment, beta-blockers remained significant. Conclusion: Drug dispensations differed up to 15 years pre-MS onset and may reflect early disease.