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.
Mortality Rates
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:
- coronary artery bypass graft (CABG) surgery
- heart attack (acute myocardial infarction [AMI])
- heart failure (HF)
- pneumonia
- chronic obstructive pulmonary disease (COPD)
- stroke
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.
Unplanned Hospital Visits
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 and a hospital's rates of readmission are compared 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.
Hospital Return Days is a measure of the average number of unplanned days patients spend back in the hospital soon after they are discharged. Hospital Return Days include time spent in the emergency department, under observation, or in an inpatient hospital unit. Hospital Return Days are calculated for specific categories of patients.
Admissions and ED Visits for Patients Receiving Outpatient Chemotherapy is a measure to assess the care provided to cancer patients and reduce the number of potentially avoidable inpatient admissions and ED visits among patients receiving outpatient chemotherapy. Potentially preventable clinical conditions that are frequent side effects of chemotherapy include anemia, dehydration, diarrhea, emesis, fever, nausea, neutropenia, pain, pneumonia, or sepsis.
Hospital Visits after Outpatient Surgery is a measure of the predicted to expected number of all-cause, unplanned hospital visits within 7 days of a same-day surgery. There are well-described and potentially preventable adverse events that occur after outpatient surgery, which can result in unanticipated hospital visits. Similarly, direct admissions after surgery that are primarily caused by non-clinical patient considerations, such as lack of transport home upon discharge, or facility logistical issues, such as delayed start of surgery, are common causes of unanticipated yet preventable hospital admissions following same-day surgery.
Surgical Complications
A CMS measure for complications of hip/knee replacements is an estimate of complications within an applicable time period, for patients electively admitted for primary total hip and/or knee replacement. CMS measures the likelihood that at least 1 of 8 complications occurs within a specified time period. CMS chose to measure these complications within the specified times because complications over a longer period may be impacted by factors outside the hospitals' control like other complicating illnesses, patients' own behavior, or care provided to patients after discharge. This measure is separate from the serious complications measure (and is based on the following potential complications:
- Heart attack (acute myocardial infarction [AMI]), pneumonia, or sepsis/septicemia/shock during the index admission or within 7 days of admission;
- Surgical site bleeding, pulmonary embolism, or death during the index admission or within 30 days of admission; or
- Mechanical complications or periprosthetic joint infection/wound infection during the index admission or within 90 days of admission.
Other measures of surgical complications are drawn from the Agency for Healthcare Research and Quality (AHRQ) Patient Safety Indicators (PSIs). 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:
- Pressure sores (pressure ulcers)
- Collapsed lung that results from medical treatment (Iatrogenic pneumothorax)
- Infections from a large venous catheter (central venous catheter-related blood stream infection)
- Broken hip from a fall after surgery (postoperative hip fracture)
- Blood clots, in the lung or a large vein, after surgery (perioperative pulmonary embolism or deep vein thrombosis)
- Blood stream infection after surgery (postoperative sepsis)
- A wound that splits open after surgery (postoperative wound dehiscence)
- Accidental cuts and tears (accidental puncture or laceration)
Healthcare Associated Infections
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). 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.