MRI utilization during the diagnostic and post-diagnostic phases in multiple sclerosis

Background: Magnetic resonance imaging (MRI) plays an important role in the diagnosis and monitoring of people with multiple sclerosis (MS). MRI rates in MS populations are poorly understood. Although Canada has universal health care, socioeconomic status (SES) is associated with MRI use. It is unknown if such disparities persist for specific conditions such as MS when care is managed centrally, or how disease-specific characteristics may affect MRI use. Objective: To assess magnetic resonance imaging (MRI) use in MS and control participants and its association with participant characteristics. Methods: Using administrative and clinical data from Manitoba, Canada, we assessed MRI use in MS and control participants during the five years pre-index (first demyelinating claim in the administrative cohort or symptom onset in the clinical cohort), between index and diagnosis (third demyelinating claim in the administrative cohort or diagnosis date in the clinical cohort), and the five years post-diagnosis. Using zero-inflated Poisson regression, we assessed associations between participant characteristics and index year, and MRI use during these three phases. Results: We included 2,763 MS cases and 13,815 controls in the administrative cohort, and 961 MS cases in the clinical cohort. MRI use increased over time, but more in cases than in controls. Pre-index, individuals aged < 50 years at the index date had lower MRI rates than those aged >= 50 years. Sex, socioeconomic status and region were not associated with MRI use. Disease-modifying therapy use was associated with 25% more MRIs post-diagnosis (adjusted rate ratio: 1.25; 95%CI:1.09-1.43) in the clinical cohort. Conclusion: Our findings suggest equity of access to MRI across sex, region and socioeconomic status in MS.