Treatment response score to glatiramer acetate or interferon beta-1a

OBJECTIVE: To compare the effectiveness of glatiramer acetate (GA) vs intra-muscular Interferon beta-1a (IFNbeta-1a)), we applied a previously published statistical method, aimed at identifying patients' profiles associated with efficacy of treatments.METHODS: Data from 2 independent multiple sclerosis datasets, a randomized study (the CombiRx trial, evaluating GA vs IFNbeta-1a and an observational cohort extracted from MSBase, were used to build and validate a treatment response score, regressing annualized relapse rates (ARRs) on a set of baseline predictors.RESULTS: The overall ARR ratio of GA vs IFNbeta-1a in the CombiRx trial was 0.72. The response score (made up of a linear combination of age, sex, relapses in the previous year, disease duration and EDSS) detected differential response of GA vs IFNbeta-1a: in the trial, patients with the largest benefit from GA vs IFNbeta-1a (lower score quartile) had an ARR ratio of 0.40 (95%confidence interval [CI] = 0.25-0.63), those in the 2 middle quartiles of 0.90 (95% CI = 0.61-1.34) and those in the upper quartile of 1.14 (95%CI = 0.59-2.18) (heterogeneity p = 0.012); this result was validated on MSbase, with the corresponding ARR ratios of 0.58 (95% CI = 0.46-0.72), 0.92 (95% CI = 0.77-1.09) and 1.29 (95% CI = 0.97-1.71); heterogeneity p < 0.0001).CONCLUSIONS: We demonstrate the possibility of a criterion, based on patients' characteristics, to choose whether to treat with GA or IFNbeta-1a. This result, replicated on an independent real-life cohort, may have implications for clinical decisions in everyday clinical practice.