Contributions
Abstract: EP1721
Type: Poster Sessions
Abstract Category: Therapy - Others
Introduction: Randomized controlled trials (RCTs) are the principal source of evidence for the treatment guidelines of multiple sclerosis (MS). Generally, placebo or an active comparator are used as the control in these trials. Intuitively, no effect on the disease course in the placebo arm is expected in addition to the regression to the mean bias.
Aim: In this study, we aimed to compare the magnitude of the regression to the mean bias in the placebo-treated patients over the years.
Methods: We included all phase II and III RCTs on relapsing remitting MS. We collected data including gender ratio, disease duration, annualized relapse rates, number of relapses, and Expanded Disability Status Scale (EDSS) scores of the placebo-treated patients. We divided the RCTs into two groups according to the studies' publication dates (Group I: studies before 2010, Group II: studies after 2010).
Results: Baseline demographic characteristics of the patients did not differ regarding gender ratio and disease duration between group I and II. However, there was a significant reduction in the ARR in the placebo-treated patients between the groups (Group I: 1.0±0.3 vs. group: II 0.5±0.2; p< 0.001). We also observed a significant increase in the relative reduction of ARR (Group I: 42.1±19.9 vs. group II: 51.0 ± 12.8; p=0.017), although the mean EDSS score before study entry was significantly higher in group II (Group I: 2.3±0.3 vs. group II: 2.6±0.3; p=0.026).
Discussion: Our study suggests the presence of an increased regression to the mean bias of the placebo-treated groups in recent studies, despite the fact that patients with higher EDSS scores were being recruited over the years. This finding should be taken into consideration in the design of future RCTs.
Disclosure: Nothing to disclose for all authors.
Abstract: EP1721
Type: Poster Sessions
Abstract Category: Therapy - Others
Introduction: Randomized controlled trials (RCTs) are the principal source of evidence for the treatment guidelines of multiple sclerosis (MS). Generally, placebo or an active comparator are used as the control in these trials. Intuitively, no effect on the disease course in the placebo arm is expected in addition to the regression to the mean bias.
Aim: In this study, we aimed to compare the magnitude of the regression to the mean bias in the placebo-treated patients over the years.
Methods: We included all phase II and III RCTs on relapsing remitting MS. We collected data including gender ratio, disease duration, annualized relapse rates, number of relapses, and Expanded Disability Status Scale (EDSS) scores of the placebo-treated patients. We divided the RCTs into two groups according to the studies' publication dates (Group I: studies before 2010, Group II: studies after 2010).
Results: Baseline demographic characteristics of the patients did not differ regarding gender ratio and disease duration between group I and II. However, there was a significant reduction in the ARR in the placebo-treated patients between the groups (Group I: 1.0±0.3 vs. group: II 0.5±0.2; p< 0.001). We also observed a significant increase in the relative reduction of ARR (Group I: 42.1±19.9 vs. group II: 51.0 ± 12.8; p=0.017), although the mean EDSS score before study entry was significantly higher in group II (Group I: 2.3±0.3 vs. group II: 2.6±0.3; p=0.026).
Discussion: Our study suggests the presence of an increased regression to the mean bias of the placebo-treated groups in recent studies, despite the fact that patients with higher EDSS scores were being recruited over the years. This finding should be taken into consideration in the design of future RCTs.
Disclosure: Nothing to disclose for all authors.