Hospital stays certainly are shorter now: the average stay was 4.6 days in 2007, down from about 5.7 days in 1993. But the readmissions problem is not simply the result of compressed care, experts say.

“Hospitals tend to focus their efforts on the admissions process, because that’s when the patient is most sick,” said Dr. Mark V. Williams, one of the authors of the study. “The discharge process can be just as important but rarely gets the same level of attention.”

At discharge, the assumption is that the patient is better and all will be fine, said Dr. Eric A. Coleman, a geriatrician and professor of medicine at the University of Colorado Denver. But many patients, especially older ones, leave the hospital with a host of issues to manage. They may have additional medications to take, new symptoms to monitor and follow-up appointments to keep, all of which require focused attention at a time when patients may not be at their sharpest.

What’s more, while insurers will pay for limited hospital stays, there’s no financial incentive for hospitals to insure that patients get out and stay out. “A hospital may actually be financially rewarded for a mishandled discharge,” said Dr. Williams, chief of hospital medicine at Northwestern University. “If the patient is readmitted, they get paid again.”

Discharge planning winds up being an overlooked issue because it “falls into the space between billable events,” said Dr. Coleman.