Is Medicare Hip/Knee Replacement Data Flawed?

A new study from AARP (formerly the American Association for Retired Persons) raises troubling questions about Medicare’s Hip/Knee Replacement data.

Medicare recently reported that readmission rates for hip/knee replacement patients were falling—specifically that readmission rate within 30 days after hip replacement in 2009 was 42 per 1, 000 patients. By 2013, those rates had fallen to 34 per 1, 000 patients. For knee surgeries, the 2009 readmission rate was 45 per 1, 000 patients, and that rate fell to 34 per 1, 000. In 2013, nearly 450, 000 people got new knees or hips. Medicare spent $6.6 billion for their surgeries and treatment.

A new study from AARP, however, questioned the Medicare numbers. Lead author, Leigh Pervis, director of health services at the AARP Public Policy Institute, noted that the drop in readmission rates was only for patients on Medicare. For younger patients, those too young to be on Medicare but undergoing the same surgery, the study turned out differently. According to Pervis, for folks under 65, there was very little change in the rate of readmission.

Pervis found that for hip surgery, readmission rates dropped 38% for Medicare patients but just 3% for patients between the ages of 50 and 64. For knee surgery, the decline among the older group was 36%, compared with 12% among the younger group.

Bob Rosenblatt, writing for Next Avenue about the AARP study suggests that the rates of readmissions in Medicare are not what they seem to be because hospitals are putting more and more patients on “observation status.” Observation status means that when a patients returns to the hospital, that he or she is put in a bed and treated but is not counted as an official admission.

This is happening because hospitals have been reducing readmissions among the Medicare population ever since the federal government began levying financial penalties for readmissions. Between 2011 and 2014 hospitals have paid $420 million in fines for readmissions, according to a Kaiser Health News report quoted by Rosenblatt.

Another source of the problem is difficulty with the surgery itself. The implant sites can become infected or doctors may not install the implants properly. The AARP study said: “It is notable that device complications were responsible for a large share of hospital readmissions following a hip or knee replacement. In fact, “the share of hospital readmissions linked to device complications actually increased between 2009 and 2013 among the 65- to 84-year-old age group.”

The study went on to state that “medical experts have consistently expressed concerns that the U.S. Food and Drug Administration does not adequately regulate the safety and effectiveness of medical devices like artificial joints. The results of our analysis should serve as a warning to supporters of recent efforts to further reduce such oversight.”

The study is titled “Impact of the Medicare Hospital Readmission Reduction Program on Hospital Readmissions Following Joint Replacement Surgery”.