Multiple sclerosis and neuromyelitis optica spectrum disorders in Argentina: comparing baseline data from the Argentinean MS Registry (RelevarEM).

Unlabelled: The objective of this study was to describe and compare the baseline epidemiological data of multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD) patients included in RelevarEM (Clinical Trials registry number NCT03375177).

Methods: RelevarEM is a longitudinal, strictly observational MS and NMOSD registry in Argentina. Epidemiological and comorbidity data from MS and NMOSD patients were described and compared. For comorbidities, the Charlson comorbidity index (CCI) was used to calculate the burden at entry. CCI was stratified in 0 and ≥ 1 and described for the entire cohort.

Results: A total of 1588 and 75 MS and NMOSD patients (respectively) were included. For MS patients, the mean age was 42 ± 7 years, female sex 65.3%, mean EDSS 2, and mean disease duration 8 ± 6 years. In NMOSD, the mean age was 40 ± 7 years, female sex 78.7%, mean disease duration 5 ± 3.5 years, and mean EDSS 2.5. The most frequent MS phenotype was RRMS in 82.4%. In MS, the CCI was 0 in 85.8.2% while ≥ 1 was in 14.2% of patients. Regarding phenotype stratification, CCI ≥ 1 was 3.9% in CIS, 13.5% in RRMS, 28.7% in SPMS, and 17.4% in PPMS (p < 0.001 between groups). In NMOSD, the CCI was 0 in 64% while ≥ 1 was in 36%. The MS/NMOSD ratio found was 21/1.

Conclusions: This is the first analysis of the longitudinal Argentinean registry of MS and NMOSD describing and comparing conditions that contributes to provide reliable real-world data in the country.