FRIDAY, May 11 (HealthDay News) -- Regions of the United States with lots of hospital beds and a large population of lower-income patients tend to have higher hospital readmission rates than regions with fewer beds and a more affluent, healthier population, new research finds.

Factors related to supply and demand had more of an influence on readmission rates than the severity of the illness or the quality of care received by patients the first time they were admitted into the hospital, the study showed.

High hospital readmission rates, in which a patient is discharged but lands up back in the hospital soon after, is considered a key driver of soaring medical costs, and there have been many efforts over the past several years to try to keep people from returning to hospitals by improving follow-up care after discharge, with home health nurses, primary care doctors and other outpatient services.

Hospital readmission rates in the United States range from 10 percent to 32 percent, according to the study.

Based on their findings, researchers argued that new Medicare regulations that punish hospitals for high readmission rates may not actually improve care.

"We have to find ways to help hospitals and communities address this problem together, as opposed to putting the burden on hospitals alone," study author Dr. Karen Joynt, an instructor at Brigham and Women's Hospital, Harvard Medical School and the Harvard School of Public Health, said in a news release. "We need to think less about comparing hospitals to each other in terms of their performance and more about looking at improvement in hospitals and communities."

Researchers examined billing records from more than 3,000 hospitals across the United States from 2008 to 2009 involving more than 1 million elderly Medicare patients with heart failure. Patients' average age was 81. About 55 percent were female and 11 percent were black.

Communities with higher readmission rates were more likely to have a greater number of physicians and hospital beds. These supply-side factors accounted for 17 percent of the discrepancy in readmission rates.

The researchers also found the patients at these hospitals were likely to be poor, black and relatively sicker. Poverty and minority racial makeup accounted for 9 percent of the difference in readmission rates.

Meanwhile, hospital-performance quality accounted for 5 percent of the difference in readmission rates, and the severity of patients' illness accounted for 4 percent.

The U.S. Centers for Medicare and Medicaid Services plans to reduce payments to hospitals with higher-than-average 30-day readmission rates related to heart failure, heart attack and pneumonia next year, according to the authors. They argued this measure ignores the supply-side factors and societal influences driving readmission rates.

"To really address the readmissions issue, we need to think about this in terms of community and population health," Joynt noted. "Focusing on community-level factors -- such as the supply and mix of physicians and targeting efforts towards poor and minority communities -- may be more fruitful approaches to reducing readmissions. We need to think outside the walls of the hospital."

The study was expected to be presented Friday at the American Heart Association's Quality of Care and Outcomes Research meeting in Atlanta. Because this study was presented at a medical meeting, the data and conclusions should be viewed as preliminary until published in a peer-reviewed journal.

More information

The U.S. Department of Health and Human Services provides more information on hospital readmissions.