By Melissa Attias, CQ Staff

April 3, 2009 -- Almost one-fifth of Medicare beneficiaries who are discharged from a hospital are readmitted within 30 days, according to a new study in the New England Journal of Medicine.

The study also found that 34 percent of patients are readmitted within 90 days while 56 percent of patients are readmitted within one year.

These rehospitalizations cost Medicare an estimated $17.4 billion in 2004, according to the study. Medicare pays for all rehospitalizations except when patients are readmitted for the same condition within 24 hours after their discharge.

The study comes just one month after President Obama released his budget for fiscal year 2010, which includes measures to reduce hospital readmissions. By providing better care after a hospital stay, the budget indicated that Medicare would save roughly $26 billion over 10 years.

The results of the study are also consistent with MedPAC's 2008 report, which said 18 percent of Medicare hospitalizations result in readmissions within 30 days of discharge. The MedPAC report said these readmissions account for $15 billion in spending, $12 billion of which are potentially preventable.

The new study analyzed data from the Medicare Provider Analysis and Review (MEDPAR) file for the 15-month period from Oct. 1, 2003 to Dec. 31, 2004. It compiled data on follow-up visits from the 2003 national sample in the Centers for Medicare and Medicaid Services' Chronic Condition Data Warehouse.

The data shows that 67 percent of patients who were discharged with medical conditions and 51.5 percent of those discharged after surgical procedures were rehospitalized or died within one year of discharge. For half of patients readmitted within 30 days, the study found that there was no bill for a physician between the time of discharge and the time of readmission. Researchers estimated that 10 percent of readmissions were likely to have been planned.

In addition, the data shows that 70.5 percent of patients rehospitalized within 30 days of a surgical discharge were readmitted for a medical condition. The five most common surgical procedures that result in hospital readmission are cardiac stent placement, major hip or knee surgery, vascular surgery, major bowel surgery, and other hip or femur surgery, according to the study. The five most common medical conditions are heart failure, pneumonia, chronic obstructive pulmonary disease, psychoses, and gastrointestinal problems, researchers said.

The study also shows that the average stay of rehospitalized patients was 0.6 days longer than patients with similar diagnoses whose most recent hospitalization had been at least six months previously. Researchers found that the reason for readmission and the length of stay are more powerful predictors of the risk of rehospitalization than demographic factors.

Finally, the study showed a wide variation in the rates of rehospitalization from state to state. The five states with the highest readmission rates (Maryland, New Jersey, Louisiana, Illinois, and Mississippi) had rates 45 percent higher than the five states with the lowest rates (Idaho, Utah, Oregon, Colorado, and New Mexico).

Yet hospital readmission rates can and should be reduced, researchers said. Their report cites previous studies that show that certain interventions at the time of discharge, such as assistance with medication management, will decrease the risk of rehospitalization.

In addition, researchers said supportive palliative care that focuses on reducing the severity of symptoms can reduce hospital readmission rates and increase patient satisfaction. Patients would also benefit if hospital physicians coordinate prompt follow-up care after they are discharged, researchers said.

"You have to worry about a system in which patients are rehospitalized soon after discharge with no bill for a physician visit in between," said Stephen F. Jencks, one of the authors of the study, in a news release. "If we want to prevent unplanned rehospitalizations, we have to help hospitals and community healthcare providers implement transition procedures that are more patient-centered."