Knee and hip replacements have extensive non-medical benefits, finds study

BMJ 2013; 346 doi: (Published 20 March 2013) Cite this as: BMJ 2013;346:f1817
  1. Bob Roehr
  1. 1Washington, DC

Working age adults in the United States who had a total knee replacement were 20% more likely to become employed, and their average annual income rose by $4300 (£2800; €3340), a study has found. They also had six fewer days off work with sickness than those who did not have replacement surgery, and they reduced their reliance on disability benefits. Similar benefits were seen with hip replacements.

The analysis drew primarily on data from 185 829 adults not living in institutions who participated in the Centers for Disease Control and Prevention’s National Health Interview Survey, conducted between 2004 and 2010.1 The survey captures physical function, patient characteristics, and economic information.

Information on functional activity such as walking a quarter of a mile, climbing steps, and carrying a bag of groceries is recorded on a five point scale that ranges from “Not at all difficult,” to “Can’t do it at all.” The study used that information to create a functional ability index.

Not surprisingly, there was “a relatively consistent dose-response relationship correlating rising levels of physical difficulty with declining economic outcomes,” the authors of the study wrote.

They also used historical data on improved functionality after knee and hip replacement surgery that was gathered prospectively in clinical studies.

The study found that each 1% increase in the index value was associated with a 2.3% increase in the odds of being employed, a 3% decline in rate of work days missed (if employed), an additional $180 in annual household income, and a 2% decline in the odds of receiving supplemental security income for disability.

The improved function associated with total hip replacement was consistent with a 27-28% increase in employment, $5400 to $6200 rise in annual household income, 19-22 fewer missed work days, and a 23-24% decrease in probability of receiving social security insurance payments.

Both the number of these joint replacements and their costs are large. A study in 2011 found that Medicare paid an average of $22 611, and private insurers an average of $25 872 for knee replacement surgery.2

The lead author of the latest study, Timothy Dall, said: “We’re breaking new ground in being able to quantify the indirect value of common bone and joint procedures. This information on the indirect economic impact of treatment and the patient’s quality of life combined with direct medical costs is needed to fully understand the net value of treatment.”

The analysis was funded by the American Academy of Orthopedic Surgeons and conducted by a team of health economists at independent consulting firms.


Cite this as: BMJ 2013;346:f1817