Irelia stuns with higher %hp

I don't have the clip, but I was playing Xin and me and Irelia were both full HP, so equal %. Irelia Q's me then stuns me. If we are both at equal % and she deals damage to me without me doing any damage to her, my % HP should be lower than Irelia's, yet her E stunned me. I've never had a way to be certain that Irelia's E sometimes stuns people with a lower % HP, but logically, there is no possible way that in this situation she could have lower or equal % hp.