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Hospital Performance Rankings Limitations and Considerations

Data source: We computed home health care rankings using publicly reported data downloaded from the CMS Medicare website ( - last accessed 11/22/20161). This data set contains hospital-specific performance on process of care quality measures2 and 11 HCAHPS (patient experience of care) measures3 for over 4,500 hospitals nationwide. The data presented on Hospital Compare comes from hospitals that voluntarily submit their data for public reporting. Approximately 98% of eligible hospitals nationwide are participating. Those not participating have no data posted on the website and are not included in the rankings.

Hospital Compare displays data provided by acute care (prospective payment hospitals - PPS) and critical access hospitals (CAHs). Long-term acute and acute rehabilitation hospitals are not eligible to report data.

CAHs that have also agreed to participate in the HQA, do not receive any financial incentive to report their data. These hospitals can elect to submit data for any or all of the measures or can elect to withhold the data from display on Hospital Compare.

Data Limitations

  • The process of care measures used to compute rankings consist of one global prevention measure and process of care measures from five clinical topic areas: heart attack; heart failure; stroke; blood clot prevention and care; and surgical care Even within these areas, they reflect only a portion of the patient care experience. Process of care measures for other conditions are not reported and are not incorporated into the rankings.
  • The quality measures presented on Home Health Compare come from information collected by Medicare and Medicaid-certified home health agencies. This information is called the Outcome and Assessment Information Set (OASIS). OASIS is a group of elements that represent core items of a comprehensive assessment for an adult home care patient. All of these data are reported by the home health agencies themselves and are not formally audited to ensure accuracy.
  • Because of differences in hospital size, the types of patients they care for, and sampling strategies, the numbers of patients used to compute reported performance rates from the Quality Measures varies by hospital, clinical topic, and measure. This impacts the precision with which performance can be ranked.
  • Hospital Compare displays data from discharges that occurred between 9 and 21 months ago. More recent changes in hospital performance are not reflected in the rankings.

Analytic considerations:

  • The process of care measures reflect processes of care supported by clinical science rather than patient outcomes. For these types of measures, risk adjustment is not considered to be necessary. 100% performance is achievable for all measures used in the rankings.
  • For the process of care measures the extent to which each indicator contributes to a hospital's overall ranking is proportional to the number of cases reported for that measure.
  • For the HCAHPS all measures contribute equally to a hospital's overall ranking.
  • Our ranking approach attempts to emphasize and anticipate a hospital's ability to improve performance across their system rather than only within focused areas.
  • While percentile scores, by definition, always range from 0-100, reported performance on a given indicator may cluster very tightly.
  • A single composite performance score or ranking can mask either strong or weak performance in specific indicators.

1 This currently includes data from the time period 1/1/2015 to 12/31/2015 for the process of care and patient experience of care measures and 7/1/2012 to 6/30/2015 for the 30-day mortality and readmissions measures. To obtain a copy of the database, go to: Hospital Compare and click on "Download Database".

2The Quality Measures are:

  • Heart Attack (Acute Myocardial Infarction or AMI)
    • Fibrinolytic medication within 30 minutes of arrival (AMI-7a)
    • PCI within 90 minutes of arrival (AMI-8a)
    • Statin prescribed at discharge (AMI-10)
    • Fibrinolytic medication within 30 minutes of arrival for outpatients (OP-2)
    • Aspirin at arrival for outpatients (OP-4)
  • Prevention
    • Influenza Immunization (Imm-2)
  • Stroke
    • VTE prophylaxis (STK-1)
    • Thrombolytic therapy (STK-4)
    • Discharged on statin medication (STK-6)
    • Stroke education (STK-8)
  • Blood Clot (VTE) Prevention and Treatment
    • VTE prophylaxis (VTE-1)
    • VTE prophylaxis for ICU patients (VTE-2)
    • VTE patients with anticoagulation overlap therapy (VTE-3)
    • VTE patients receiving IV blood thinner who were appropriately monitored (VTE-4)
    • VTE patients discharged on a blood thinner who received written instructions on that medicine (VT-5)
    • Patients who did not receive preventive treatment for VTE and who acquired a blood clot in the hospital (VTE-6)

Click here for a description of the quality measures for hospitals.

3The HCAHPS Measures and the response levels reported by CMS are:

  • How often did nurses communicate well with patients? (Sometimes or Never; Usually; Always)
  • How often did doctors communicate well with patients? (Sometimes or Never; Usually; Always)
  • How often did patients receive help quickly from hospital staff? (Sometimes or Never; Usually; Always)
  • How often was the patient's pain well controlled (Sometimes or Never; Usually; Always)
  • How often did staff explain about medicines before giving them to patients? (Sometimes or Never; Usually; Always)
  • Were patients given information about what to do during their recovery at home (No; Yes)
  • Patients understood their care when they left the hospital (Strongly Disagree or Disagree; Agree; Strongly Agree)
  • How often were the patients' rooms and bathrooms kept clean? (Sometimes or Never; Usually; Always)
  • How often was the area around the patient's rooms kept quiet at night? (Sometimes or Never; Usually; Always)
  • How do patients rate the hospital overall? [on a scale of 1-10: 6 or lower (low); 7 or 8 (medium); 9 or 10 (high)]
  • Would patients recommend the hospital to friends or family? (No, Probably; Definitely)