Stroke trials

One of the most commonly used clinical outcomes in acute stroke trials is the 3-month modified Rankin Scale (mRS), an ordinal scale that ranges from 0 (no symptoms) to 6 (death). Traditionally, the mRS is dichotomized into excellent (0–1 vs 2–6) or good (0–2 vs 3–6) outcome. Alternately, shift analysis compares the distribution of outcomes between the treatment and control groups across the entire ordinal scale, thus answering the question of whether there is any measurable improvement on the mRS associated with treatment. The two approaches target different types of departures from the null hypothesis of no difference in outcome between treatment and control groups. Hence, applying the appropriate analytic strategy to the expected departure can increase power and reduce the number needed to prove a benefit in clinical trials. In this issue of Neurology ®, Saver and Gornbein1 explored statistical approaches to ordinal outcome data …