Abstract
BACKGROUND: Investigations of a prodrome in multiple sclerosis (MS) usually have included adults. OBJECTIVE: To compare rates and reasons for health care use in youth with and without MS, considering time relative to the MS index date and to birth. METHODS: This retrospective cohort study used population-based administrative data (1991-2020) from Ontario, Canada. We matched youth (<18 years) with MS up to 5:1 to youth without MS by sex, birth year, region, and duration of observation (full cohorts). Subcohorts had data from birth to MS index date (first demyelinating disease claim). We compared health services use, adjusting for age, sex, area-level income, region, and year. RESULTS: We included 451 individuals with pediatric-onset MS and 1422 without MS. As of 6 years pre-index, the full MS cohort had higher physician services use (year 6: rate ratio (RR) = 1.45; 95% confidence interval (95% CI) = 1.25-1.67) and hospitalizations (RR = 2.79; 95% CI = 1.31-5.94). Findings were similar in subcohorts. The MS subcohort had elevated physician visit rates in early life that rose as the MS index date approached. DISCUSSION: Youth with pediatric-onset MS exhibit increased health care use from birth. Early life may be a risk period for MS. A prodromal phase may emerge 6 years before the onset of typical MS symptoms.