Improving the Efficiency of Stroke Trials: Feasibility and Efficacy of Group Adjudication of Functional End Points

Background and Purpose—Use of the modified Rankin scale (mRS) in multicenter trials may be limited by interobserver variability. We assessed the effect of this on trial power and developed a novel group adjudication approach. Methods—We generated power and sample size estimates from simulated trials modeled with varying mRS reliability. We conducted a virtual acute stroke trial across 14 UK sites to develop a group adjudication approach. Traditional mRS interviews, performed at local sites, were digitally recorded and scored by adjudication committee. We assessed the effect of translation by comparing scores in translated mRS interviews, originally conducted in English and Mandarin. Agreement was measured using κ and weighted κ (κw) statistics and intraclass correlation coefficient. Results—Statistical simulations suggest that improving mRS reliability from κ=0.25 to κ=0.5 or 0.7 may allow reductions in sample size of n=386 or 490 in a typical n=2000 study. Our virtual acute stroke trial included 370 part...