Income inequality in the U.S. has grown over the past several decades. And as the gap between rich and poor yawns, so does the gap in their health, according to a study published in JAMA Network Open Friday.

The study drew from annual health survey data collected by the Centers for Disease Control and Prevention from 1993 to 2017, including around 5.5 million Americans ages 18-64. The researchers focused on two questions from the survey recommended by the CDC as reliable indicators of health: 1. Over the last 30 days, how many healthy days have you had? 2. On a scale of 1 to 5, how would you rate your overall health?

What they found: Across all groups, Americans’ self-reported health has declined since 1993. And race, gender and income play a bigger role in predicting health outcomes now than they did in 1993. Overall, white men in the highest income bracket were the healthiest group.

“And actually, what’s happening to the health of wealthier people is that it’s remaining relatively stagnant, but the health of the lowest income group is declining substantially over time,” says Frederick Zimmerman, the study’s lead author and a professor at the UCLA Fielding School of Public Health.

The researchers looked at differences in health between white and black people and between three income brackets. They assessed the degree to which race, income and gender influenced health outcomes over time, a measure they called “health justice.”

Finally, they calculated the gap between people’s health outcomes and that of the most privileged demographic: high-income white men.

“Results of this analysis suggest that there has been a clear lack of progress on health equity during the past 25 years in the United States,” the researchers write.

Income was the biggest predictor of differences in health outcomes, according to Zimmerman. Health differences between the highest income group and lowest income group increased “really quite dramatically,” he says.

Things weren’t all negative. On one measure — disparity between health outcomes for black and white people — the gap between health outcomes narrowed significantly.

Read the rest of the article at NPR