An Obamacare program that aims to improve American health care may have an unintended side effect: penalizing hospitals that serve the sickest and poorest patients.

The Affordable Care Act penalizes hospitals that have high readmission rates, where patients come back within 30 days. The aim of that program was to encourage doctors to do the best job possible on the first hospital visit, improving patients’ experience and saving money by preventing a second trip.

But a new paper from three Harvard health-care experts suggests that the readmission program is penalizing hospitals for the type of patients they see. Hospitals that have high readmission rates tend to see patients who are less educated, more disabled, and more likely to suffer from depression — factors the Obamacare program doesn’t account for.

Read the article “STUDY: Obamacare Punishes Hospitals that See Poor Patients” on vox.com.