Patients who make $35,000 a year or less report better outcomes after knee replacement surgery than people who earn more, research by Mayo Clinic and the University of Alabama at Birmingham shows. The lower-income patients studied reported less pain and better knee function at their two-year checkups than wealthier people did.
The study was being presented at the American College of Rheumatology annual meeting in Washington.
The finding is important as physicians try to figure out why some patients do better than others after knee replacement, says David Lewallen, M.D., an orthopedic surgeon at Mayo Clinic in Rochester, Minn., who conducted the study with Jasvinder Singh, M.D., of the University of Alabama at Birmingham.
“It runs counter to what many might have expected to see,” Dr. Lewallen says. “We need to work to understand it further.”
One possible explanation: Many lower-income patients delay knee replacement as long as possible, so their knees tend to be in worse shape and their feeling of improvement after the procedure more dramatic, he says.
Drs. Lewallen and Singh used the Mayo Clinic Total Joint Registry to assess the association of income with knee function and moderate to severe pain as reported by patients at follow-up appointments after knee replacement. The registry has data on nearly all of the 100,000 joint replacements at Mayo Clinic since it performed the first FDA-approved total hip replacement roughly 43 years ago. The researchers adjusted for other factors previously found to be linked to patient-reported outcomes after knee replacement, such as age, gender, body mass index and underlying diagnosis.
They found that those making $35,000 or less rated their overall improvement in knee function “better” more often at their two-year follow-ups than those who earned more, and also were less likely to report moderate to severe pain. The finding means that all other things being equal, a low income doesn’t necessarily mean a patient will see poorer results from knee replacement, Dr. Lewallen says.
“This is one small piece of a very large puzzle in understanding patient outcomes following a well-defined surgery that we know is very effective for most,” Dr. Lewallen says.
Total knee replacement is among the procedures that patients rate most highly as improving their quality of life, along with total hip replacement and cataract surgery, he says.
Disclosures: Dr. Singh received research and travel grants from Takeda, Savient, and consultant fees from URL Pharma, Savient, Takeda, Regeneron, ArdeaBioscience, Allergan and Novartis. Dr. Lewallen receives royalties from Zimmer for hip and knee implant devices; consulting fees from Pipeline Biomedical; and research funding from DePuy, Stryker, Zimmer and Biomet.
As a Physical Therapist seeing these patients I can say unequivocally that this is not true. Study needs to be duplicated over a larger sample and financial categories expanded
I agree with ken, that there needs to be a much larger sample population than only the patients from Mayo’s Orthopedic Surgery Department. From my experience from being a patient on the Orthopedic Surgery floor, is that these findings are more about how doctors perceive people with less income and education and how they interact with them. I have no doubt that gender can be included in a similar equation. This should be a behavioral and psychological window into the behavior and actions of the doctor and how it relates to the patient. There is probably more of a problem with their being a disconnect between the doctor and the lower income patient. Talk to your colleagues in psychiatry and look at this question of why people in the lower economic sphere, during two intervals, say they are doing well in comparison to those who have more money, education and doubt themselves less when dealing with medical professionals? It would be interesting to know during which two intervals the lower class does better than the upper class? The only significance this study has is why patient registration is way down in the Orthopedic Surgery Department in comparison to ten years ago?