On 2009, at the Neurological Institute of Havana, Cuba, was conducted a double-blind, placebo-controlled study of 225 patients with clinical definite relapsing remitting (RR) MS and brain MRI confirmed. Patients were randomly assigned to receive intramuscular Interferon (IFN) alpha-2b (Heberón alfa R) 20 million IU (high dose), 6 million IU (low dose) or placebo weekly for 2 years.

The primary outcome measures were change in the yearly excerbation rate and proportion of exacerbationfree patients. Neurologic disability and changes in brain MRI were the secondary outcome measures. We did an analysis by intention to treat that included the first 17 patients at the 2-year study period. Treated low dose group showed a reduction in yearly exacerbation rate from 2,8 ± 1,1 to 0(p= 0.028) vs placebo, the high dose group from 2,3 ± 0.5 to 0,5 ±0,8(p= 0.028) vs placebo, whereas the placebo group from 2,8 ±1,1 to 1,6 ± 2,1, reflecting a reduction in relapse rate in IFN groups. Six patients in the low dose IFN alpha group were exacerbation free throughout 2-year period, 4/6 patients in the high dose whereas 2/5 in the placebo group.

Neurologic disability as measured by the Expanded Disability Status Scale (EDSS score) decreased from 5,2 ± 1 to 4,8 ± 1,8 in the low IFN dose, increased from 3,8 ±1,8 to 4,8 ± 2,2 in high dose group so long as in the placebo group from 5 ± 2 to 5,2 ± 2,9 (not statistically significant). Our results suggest that IFN alpha, mainly low dose group, produced a significant decreased in yearly exacerbation rate in RR-MS patients.