Relating Treatment Effect on Relapses with Disability Worsening in Multiple Sclerosis Patients: Age Matters*Corresponding Author:
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Objective: To determine whether treatment efficacy on relapses do enable to predict treatment efficacy on disability worsening in multiple sclerosis patients and whether that efficacy is dependent on age.
Methods: The relevant features of published randomized controlled clinical trials in MS were extracted according to defined criteria namely data on age baseline information relapses and proportion of progressing patients. Regression analyses were performed to analyse the relationship between treatment efficacy on relapses and on confirmed disability progression over trials duration as well as between age and those clinical outcomes.
Results: Fifty-three trials comprising 76 comparison arms and totalising 34.765 patients were selected and engaged in the subsequent analyses. Significant correlation was observed between the treatment effect on relapses and on confirmed disability progression (adjusted R2=0.3872). A strong association was found between the baseline EDSS and baseline age (adjusted R2=0.6243) and a significant association was registered between the treatment effect on confirmed disability progression and age (adjusted R2=0.3179). A weighted multiple linear regression between the treatment effect on confirmed disability progression and the interaction of the treatment effect on relapses with the age at disease onset interacting with disease duration exhibited a strong association (adjusted R2=0.5846).
Conclusion: These findings demonstrate that age is a significant determinant of disability, the treatment effect on relapses is correlated with its effects on disability worsening being such association affected by age and that the efficacy of disease modifying therapies in multiple sclerosis decreases with age. The results reinforce the importance of early treatment initiation with high efficacy drugs as well as the need for treatments with targets other than relapses particularly for older patients.