"Patients are often left wondering whether they have been discharged from the hospital too soon or too late. Changing economic incentives have played a role in how long patients tend to stay. Recent changes to how hospitals are paid appear to be affecting which patients are admitted and how frequently they are readmitted.One big reason for the change came in the early 1980s. Medicare stopped paying hospitals whatever they claimed their costs were and phased in a payment system that paid them a predetermined rate tied to each patient’s diagnosis. This “prospective payment system,” as it is called, shifted the financial risk of patients’ hospitalization from Medicare to the hospital, encouraging the institutions to economize.One way to economize is to get patients out of the hospital sooner.