Evolution of the Modified Rankin Scale and Its Use in Future Stroke Trials

The mRS has evolved as the primary outcome measure for acute stroke trials. Other patient-centered outcome measures not discussed in this article, such as the Euro-QOL 5-D²⁵ or Neuro-QOL,⁵³ have complementary strengths and often are used as secondary outcomes, although none have yet to be used as the primary outcome measure in a positive acute stroke trial. This could change in the future. At present, attention to training and standardization of mRS assessments, use of UW-mRS or some equivalent patient-centered outcome, and careful selection of appropriate effect size based upon previous trials and expected distribution of outcomes are important for planning of future acute stroke trials.