The results may surprise you.

Researchers from Yale, Mathematica Policy Research, Boston-based Brigham and Women’s Hospital, Vertex Pharmaceuticals and George Washington University examined the common reasons why some hospitals have more readmissions treating a disproportionate share of patients with low incomes, poor health and other negative circumstances are at a disadvantage relative to their peers.

The study published in JAMA Health Forum looked at 30-day readmission between dual-eligible and non-dual-eligible patients following admission for AMI, Heart Failure and Pneumonia.