The Hospital-acquired conditions (HAC) measures are calculations of how often a particular preventable event occurs at a given hospital among certain Medicare beneficiaries. CMS currently measures HACs considered to be rare or entirely avoidable events. The data only include patients who acquired the condition during their hospital stay; patients who arrived at the hospital with any of these conditions are not included. By law, hospitals cannot receive additional payment from Medicare or charge Medicare patients for treating these conditions.
What Patients are Included
The HAC measures apply only to Medicare beneficiaries enrolled in Original Medicare (traditional
FFS Medicare) who were discharged from a hospital paid through the Inpatient Prospective
Payment System (IPPS) after they had an inpatient stay.
The HAC measures do not include Medicare patients who arrived at the hospital and already had one of the eight HAC conditions before they were admitted for an inpatient stay. Non-Medicare patients and beneficiaries enrolled in Medicare managed care plans are also excluded from the data.
Where the Information Comes From
CMS calculates the HAC data from the claims hospitals submit for Medicare beneficiaries enrolled in Original Medicare (traditional Fee-For-Service (FFS) Medicare). The rate for each HAC measure is calculated by dividing the number of HACs that occur within any given eligible hospital by the number of eligible Medicare (FFS) discharges, multiplied by 1,000. CMS counts each HAC every time it occurs, so one Medicare beneficiary who is discharged from the hospital could have multiple different HACs on his or her record. The same HAC cannot be counted more than once on a discharge record, however. HAC data are only calculated for hospitals that are paid through the Inpatient Prospective Payment System (IPPS), which excludes Critical Access Hospitals (CAHs), Long-Term Care Hospitals (LTCHs), Maryland waiver hospitals, cancer hospitals, children's inpatient facilities, rural health clinics, federally qualified health centers, inpatient psychiatric hospitals, inpatient rehabilitation facilities, Veterans Administration/Department of Defense hospitals, and religious, non-medical health care institutions.
The HAC rates are not currently risk adjusted to account for differences in hospital patients’ characteristics. Many of these events should never occur, even if the patient is extremely sick. However, Medicare is evaluating whether some of the measures should be adjusted based on certain patient characteristics.
HAC rates are based on the actual number of HACs that are reported for a hospital at a given time period for every 1,000 Medicare FFS discharges. They are rare events and do not represent estimates of a hospital’s performance at any other time period. For this reason, no tests of statistical significance are performed, and no statistical comparisons are made to national benchmarks.
Comparing Individual Hospital Rates to Benchmarks
CMS reports the U.S. national rate of HACs per 1,000 Medicare FFS discharges. However, no statistical comparisons are made between individual hospitals and the U.S. national rate.
For more detail on HAC measures please refer to QualityNet - Hospital-Acquired Conditions (HACs).- Opens in a new window
For questions or comments about the CMS calculation or reporting of the HAC measures based on Medicare claims for the Hospital Inpatient Quality Reporting (IQR) program, please e-mail Mathematica Policy Research (CMS’ contractor) at HACmeasures@mathematica-mpr.com.