What's even more surprising? The wide variation between hospitals, in keeping their older surgery patients from needing emergency care after surgery on their hearts, hips, backs, colons and major blood vessels. Some hospitals had four times the rate of post-surgery emergency care for their patients, compared with others.

In fact, the University of Michigan Medical School team that performed the research with funding from the National Institutes of Health suggests that hospitals could be graded based on their performance on this measure.

But, they note in their paper in the September issue of the journal Health Affairs, further study is needed before post-surgical emergency visits join such measures as hospital readmissions and infections in assessing the quality of hospital care.

The new findings come from an analysis of Medicare data from nearly 2.4 million adults who had at least one of six common operations in a three-year period. More than 4 percent had two or more ED visits within 30 days of leaving the hospital.

Not only was emergency care common for seniors after surgery -- it was also a key route back to a hospital bed. More than half of the patients who sought emergency care ended up being readmitted to the hospital directly from the ED.

Since Medicare now pays hospitals less if they have high readmission rates, and reports those rates publicly, health teams nationwide have ramped up their efforts to make sure hospital patients get support that will keep them from coming back in the "revolving door." The new study suggests those teams should focus on ways to keep surgery patients from experiencing emergencies after they go home.

"This research is a high-altitude look at this problem, and suggests that we should really be doing more investigation into what is driving the frequency with which patients need to come into the emergency department," says Keith Kocher, M.D., the study's lead author and a U-M emergency physician. "We should be looking for things we can do as a health system to head off the need for an ED visit in the first place, or to deliver care in the ED that can prevent a hospital readmission if we can."

Kocher, an assistant professor of in the Department of Emergency Medicine at the U-M Medical School, worked on the study with three other U-M physicians who have led a number of studies on hospital quality after surgery and heart procedures. All are members of the U-M Institute for Healthcare Policy and Innovation.

The new study's findings come from studying post-hospital emergency care and hospitalizations among seniors who had one or more of six of the most common operations: angioplasty or other minimally invasive heart procedures, coronary artery bypass, hip fracture repair, back surgery, elective abdominal aortic aneurysm repair, and colectomy or removal of part of the colon, such as for colon cancer.

The most common issues that brought patients to the ED were cardiovascular and respiratory conditions, infections, complications with the site of their surgery or procedure incision, and abdominal or gastrointestinal problems.

"There was a lot of variation depending on what the surgery was for," Kocher notes, adding that for colon surgery, the rate of post-hospital emergency visits ranged from 1 in 4 patients treated at some hospitals, to 1 in 14 treated at others. "We went into this expecting some variation, but were surprised at how much we found. That means this is probably a finding health providers and systems can act on to improve their rates, to ensure coordination of care and that patients can access timely care for problems that develop after they are discharged before having to come to the ED."

In addition to seeing post-surgery emergency visit rates as an opportunity for surgical and inpatient teams to do a better job at educating patients and managing their care in the first days after they go home, Kocher and his colleagues see a potential role for emergency physicians as well.

"An emergency visit by a surgical patient is a signifier of a problem in the transition from the hospital to the outpatient setting," he comments. "Emergency visits by post-surgery patients could be used to re-establish coordination of care, as well as deliver treatment and create management plans to prevent readmission."

Kocher notes that some of this may already be occurring, or will soon, as accountable care organizations and other integrated systems of care come online, health providers will have even more incentive to ensure that they contain the cost and improve the overall quality and coordination of each patient's care.

At the U-M Health System's adult emergency department, for instance, adult emergency department patients have access to a care manager to coordinate patients' care across UMHS sites, and a free phone-based service that assists them in getting outpatient appointments to follow up on their health needs. UMHS also has clinical relationships with local skilled nursing facilities, to help coordinate patients' post-hospital care.

Integrating care across all settings might help hospitals reduce their post-surgery emergency care rate, Kocher says. And as readmission penalties mount, hospitals may begin to focus more on emergency physicians' decision-making process regarding readmitting a patient from the ED.

But first, further research on the reasons for these emergency visits, the impact of hospital-discharge education and planning on post-surgery ED visits, and the reasons why emergency patients are readmitted from the emergency department, is needed, he says. Social and family support reasons, not just medical considerations, may play a big role.