Annual incidence of Multiple Sclerosis in a large Health Care System in the US from 2014 to 2020
Sue Hyun Kwon1, Aaron Carlson2, Robert Valuck1, Kelly Anderson1, Kavita Nair3, Heather Anderson1
1Department of Clinical Pharmacy, University of Colorado Skaggs School of Pharmacy and Pharmaceutical Sciences, 2University of Colorado, School of Medicine, Department of Neurology, 3Department of Neurology, University of Colorado Anschutz Medical Campus
Objective:
Estimate annual incidence of MS during 2014-2020 in a large healthcare system in the US.
Background:
Previous studies measuring incidence of multiple sclerosis (MS) in the US have been limited by single payer cohorts and short observation periods. Measuring incidence in diverse cohort using established case definition and sufficient observation time has better potential to detect cases and temporal changes. Such estimation of MS incidence is valuable for the assessment of resource needs and healthcare burden.
Design/Methods:
This retrospective observational study estimated the annual incidence rate of MS from 2014 to 2020. The population was derived from a linked dataset combining the Colorado All-payers Claims Database with electronic health records from University of Colorado Health system, capturing 18.1% of the Colorado population. MS cases were initially identified using the Multiple Sclerosis Prevalence Workgroup Algorithm. The numerator included individuals in the MS case cohort who were continuously enrolled in insurance coverage for 24 months prior to the first observable MS event (index date). For each calendar year, the denominator was total person-time of the population at risk. Incidence was age-adjusted using the 2010 Census to calculate nationally representative estimates for comparability with other US studies.
Results:
A total of 1118 incident MS cases were identified from 5,080,555 total person-years of observation. The overall incidence rate of MS from 2014 to 2020 was 21.57 per 100,000 person-years (95% CI=20.29, 22.85). The incidence of MS was greatest in 2015 (26.49, 95% CI=22.74, 30.25) and the lowest in 2020 (17.48, 95% CI=14.27, 20.69). The annual percentage change of incidence was -5.07% (p=0.041).
Conclusions:
Incidence in the current all-payer cohort was higher compared to older US estimates in single payer settings. Decreasing trend of MS incidence is a trend also observed by a contemporary study in Canada. Work is in progress to describe the demography of the incident cases.