A difference in the effectiveness against strokes and other blood clots was easily visible in the first year among patients who’d taken the anticoagulant apixaban rather than rival rivaroxaban, according to Sean Hennessy, PharmD, PhD, Professor of Epidemiology and Director of Penn’s Center for Real-world Effectiveness and Safety of Therapeutics,and Ghadeer Dawwas, PhD, a postdoctoral fellow in the DBEI.