A Hospital Acquired Condition (HAC) is a medical condition or complication that a patient develops during a hospital stay, which was not present at admission. In most cases, hospitals can prevent HACs when they give care that research shows gets the best results for most patients.

For discharges occurring on or after October 1, 2008, hospitals will not receive additional payment for cases in which one of the selected conditions was not present on admission. That is, the case would be paid as though the secondary diagnosis were not present. CMS required hospitals to report present on admission information for both primary and secondary diagnoses when submitting claims for discharges on or after October 1, 2007.

The report is based on information from Medicare fee-for-service claims from short term, acute care hospitals and is not case-mix adjusted. Columns are defined as follows:

Rate per Thousand

[Rate per 1000 discharges] = [(Number of HACs / Number of Patients) x 1000]

National Rate

[National HAC Rate] = [(National HAC count/National number of eligible discharges) x 1000]

The specific measures are defined in terms of ICD-9 codes for complications appearing on Medicare claims: