Complication rate for hip/knee replacement patients
The hip/knee complication rate 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 one of eight complications occurs within a specified time period:
- Heart attack (acute myocardial infarction [AMI]), pneumonia, or sepsis/septicemia/shock during the index admission or within seven (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.
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 such as other complicating illnesses, patients’ own behavior, or care provided to patients after discharge. This measure is separate from the serious complications measure (also reported on Hospital Compare).
What patients are included
The hip/knee complication measure includes Medicare beneficiaries aged 65 or older who were electively admitted for hip/knee replacement and enrolled in Original Medicare (traditional fee-for-service Medicare) for the entire 12 months prior to their hospital admission. Beneficiaries enrolled in Medicare managed care plans are not included.
The statistical model used to calculate the complication rate also determines how precise the estimates are, and provides the upper and lower bounds of the 95% interval estimates for each hospital’s risk-adjusted complication rate. Interval estimates, which are like confidence intervals, describe the level of uncertainty around the estimated complication rates.
Comparing individual hospital rates to U.S. national rate
To assign hospitals to performance categories, the hospital’s interval estimate is compared to the U.S. national hip/knee complication rate. If the interval estimate includes and/or overlaps with the national observed hip/knee complication rate, the hospital’s performance is in the “no different than U.S. national rate” category. If the entire interval estimate is below the national observed hip/knee complication rate, then the hospital is performing “better than U.S. national rate.” If the entire interval estimate is above the national observed hip/knee complication rate, its performance is “worse than U.S. national rate.” Hospitals with fewer than 25 eligible cases are placed into a separate category that indicates that the hospital does not have enough cases to reliably tell how well the hospital is performing.
For more detail on how the hip/knee complication rates are calculated, please refer to QualityNet – Complication Measures - Opens in a new window Globe icon. For other questions regarding hip/knee complication measure, please email firstname.lastname@example.org