Outcome measures indicate what happened after patients with certain conditions received hospital care. The mortality rates focus on whether patients died within 30 days of their hospitalization. The rates of readmission focus on whether patients were hospitalized again within 30 days. Mortality rates and rates of readmission are indications of a hospital’s effectiveness in preventing complications, instructing patients at discharge, and enabling patients to make a smooth transition to their home or another setting such as a nursing home.
The hospital mortality rates and rates of readmission are based on people with Medicare who are 65 and older. These rates are calculated using Medicare enrollment and claims records, and a complex statistical procedure. The mortality rates and rates of readmission are "risk-adjusted" (i.e. the calculations take into account how sick patients were when they went in for their initial hospitalization). When the rates are risk-adjusted, it helps make comparisons more meaningful.
The 30-day death (mortality) measures are estimates of deaths from any cause within 30 days of a hospital admission, for patients hospitalized with one of several medical conditions or surgical procedures. The 30-day death rate for coronary artery bypass graft (CABG) surgery patients measure counts deaths from any cause within 30 days of the date of the surgery date. Deaths can be counted in the measures regardless of whether the patient dies while still in the hospital or after discharge. CMS chose to measure death within 30 days instead of inpatient deaths to use a more consistent measurement time window because length of hospital stay varies across patients and hospitals. Also, death over longer time periods (like 90 days) may have less to do with the care gotten in the hospital and more to do with other complicating illnesses, patients’ own behavior, or care provided to patients after hospital discharge. Hospital Compare reports on the following 30-day mortality measures:
A hospital’s mortality rates are compared with U.S. National rates to determine whether patients admitted to the hospital have mortality rates that are lower (better) than the U.S. National rate, about the same as the U.S. National rate, or higher (worse) than the U.S. National rate, given how sick they were when they were admitted to the hospital. For some hospitals, the number of cases is too small (fewer than 25) to reliably tell how well the hospital is performing, so no comparison to the national rate is shown.
Readmission rates are calculated from Medicare data and do not include people in Medicare Advantage plans or people who do not have Medicare. A “readmission” occurs when a patient who had a recent hospital stay needs to go back into a hospital again within 30 days of their discharge. Patients may have been readmitted back to the same hospital or to a different hospital or acute care facility. They may have been readmitted for the same condition as their recent hospital stay, or for a different reason.
Readmission rates are calculated for specific categories of patients:
The report also shows how a hospital’s rates of readmission compare to the U.S. National Rate. For some hospitals, the number of cases is too small (fewer than 25) to reliably tell how well the hospital is performing, so no comparison to the national rate is shown.
Measures of serious complications are drawn from the Agency for Healthcare Research and Quality (AHRQ) Patient Safety Indicators (PSIs). The hip/knee complication measure includes Medicare beneficiaries 65 or older who were electively admitted for hip/knee replacement and enrolled in fee-for-service Medicare for the entire 12 months prior to their hospital admission. The hip/knee complication rate is an estimate of at least 1 of 8 complications within an applicable time period:
The overall score for serious complications is based on how often adult patients had certain serious, but potentially preventable, complications related to medical or surgical inpatient hospital care. This composite or summary measure is based on the following measures:
The healthcare-associated infection (HAI) measures show how often patients in a particular hospital contract certain infections during the course of their medical treatment, when compared to like hospitals. These infections can often be prevented when healthcare facilities follow guidelines for safe care. To get payment from CMS, hospitals are required to report data about some infections to the Centers for Disease Control and Prevention’s (CDC’s) National Healthcare Safety Network (NHSN)- Opens in a new window. Information for CMS reporting is currently collected through NHSN about central line-associated bloodstream infections, catheter-associated urinary tract infections, surgical site infections, MRSA Bacteremia and C.difficile laboratory-identified events.