Reasons for Healthcare Use Before Onset of Multiple Sclerosis: A Nationwide Matched Cohort Study in Sweden

Background Evidence suggests signs and symptoms may emerge years before the clinical onset of multiple sclerosis (MS). We investigated secondary healthcare use and medication dispensations before MS onset. Methods Using linked administrative data, we analyzed a neurologist‐diagnosed MS clinical cohort and an algorithm‐defined administrative cohort in Sweden (2001–2019). People with MS (PwMS) were matched to up to five non‐MS comparators by sex, birth year, residency location, and residency duration before the index date (clinical: symptom onset; administrative: first MS/demyelinating diagnosis code). Annual outpatient visits and hospitalizations by diagnosis codes across 19 years pre‐index, and dispensed medications by anatomical and therapeutic classifications across 14 years pre‐index were compared. Results The clinical cohort included 7604 PwMS and 37,974 matched comparators (median age at symptom onset = 35.5; 68.5% females). In the 5 years pre‐index, outpatient visits were 11%–73% higher among PwMS for disturbances of sense organs, nervous, musculoskeletal, digestive, and genitourinary systems, mental health/behavior, and ill‐defined symptoms/signs, with visits related to sense organs elevated up to 6 years. Hospitalizations were often elevated in the year pre‐index. Dispensations of nervous system‐related, musculoskeletal, blood‐related, metabolic, sensory, respiratory, and dermatological agents were elevated by 6%–22% in the 5 years pre‐index, with elevations in nervous system‐related and musculoskeletal agents extending up to 6–9 years pre‐index. Findings were similar in the administrative cohort with greater magnitudes and longer durations pre‐index. Conclusions We observed increased hospital, outpatient, and prescription utilization for multiple body systems 6–9 years pre‐MS onset. These patterns provide a more comprehensive picture of the MS prodrome.