Abstract Glatiramer acetate currently represents one of the main treatments for relapsing-remitting multiple sclerosis (RRMS). However, the information available about its long-term effect in ...clinical practice is still limited. Thus, this multicenter retrospective cohort study aimed to assess the long-term effectiveness of glatiramer acetate in this setting. The study population included RRMS patients treated with glatiramer acetate for at least 5 years after its marketing authorization and the primary endpoint was long-term clinical effectiveness, defined as absence of disability progression for at least five consecutive years. A total of 149 patients were included into the study, who had received glatiramer acetate for a mean of 6.9 ± 1.4 years (5 years, n = 149; 6 years, n = 112; 7 years, n = 63; 8 years, n = 32; 9 years, n = 21). More than 85% of patients remained free from disability progression through years 1 to 9 of glatiramer acetate treatment, and 75.2% showed absence of disability progression for at least five consecutive years. Expanded Disability Status Scale (EDSS) scores were maintained, with most patients showing stable/improved EDSS and 92.6% sustaining EDSS <6. Decreased annual relapse rates and increased proportion of relapse-free patients were maintained during the whole glatiramer acetate treatment compared to the year prior to its authorization ( p < 0.001). The number of gadolinium-enhanced T1-weighted lesions also decreased from pre-glatiramer-acetate assessment to last follow-up whilst on glatiramer acetate ( p < 0.05). In conclusion, administration of glatiramer acetate shows long-term clinical effectiveness for RRMS treatment; its effect under clinical practice conditions slowed disability progression and reduced relapse occurrence for up to 9 years.
