Healthcare use before paediatric multiple sclerosis onset differs by age and sex: a nationwide cohort study

Background: Increased use of healthcare before multiple sclerosis (MS) onset indicates a prodromal phase. Data on the prodromal phase of paediatric-onset MS (PoMS) are sparse, especially regarding age-specific and sex-specific characteristics. The objective of this study was to examine healthcare use by age and sex before PoMS clinical onset. Methods: Individuals with MS with symptom onset before age 18 were identified in the Swedish MS registry. Rates of hospitalisations, outpatient visits and prescriptions dispensed were compared with a matched non-MS cohort for up to 16 years before MS onset, categorised by age at onset (12-15 and 16-17 years) and sex. Results: We included 233 PoMS and 1151 matched individuals. Compared with the matched cohort, females with PoMS exhibited higher annual rates of outpatient visits in the years preceding MS onset for neoplasms (rate ratios (RRs) 3.44-5.73) while males had higher rates for skin-related visits (RRs 6.00-11.00) and prescription dispensations for corticosteroids for dermatological use (year -1, RR 3.12; 95% CI 1.01 to 9.68). Older teenagers with MS had higher visit rates for neoplasms (RRs 3.98-8.70), while younger teenagers had higher nervous system-related visit rates (RRs 4.51-5.97) before MS onset. Conclusions: Individuals with PoMS showed age-specific and sex-specific increases in healthcare use before symptom onset, including skin-related visits in males and neoplasm-related visits for females and 16-17 year-olds. These results can help guide our understanding of MS mechanisms and may aid in earlier detection of MS in the paediatric population.