Total knee replacement, or arthroplasty, appears to be a cost-effective procedure for older adults with advanced osteoarthritis, says a report in a recent issue of a journal called the Archives of Internal Medicine.

The procedure appears to be cost-effective across all patient risk groups, and appeared more costly and less effective in low-volume centers than in high-volume centers.

About 12 percent of adults older than 60 have symptoms of knee osteoarthritis, and their direct medical costs are estimated to range from $1,000 to $4,100 per person per year, the article says.

"Total knee arthroplasty is a frequently performed and effective procedure that relieves pain and improves functional status in patients with end-stage knee osteoarthritis," the authors write. "Almost 500,000 total knee arthroplasties were performed in the U.S. in 2005 at a cost exceeding $11 billion. Projections indicate dramatic growth in the use of total knee arthroplasty over the next two decades."

Researcher Elena Losina, of Boston's Brigham & Women's Hospital and the Boston University School of Public Health, and colleagues developed a computer simulation model and populated it with Medicare claims data and cost and outcomes data from national and multinational sources. They then projected lifetime costs and "quality-adjusted" life expectancy—or the number of years remaining of good health—for patients at different levels of risk and receiving total knee arthroplasty at high-volume or low-volume facilities.

Overall, having a total knee arthroplasty increased quality-adjusted life expectancy of the Medicare population (average age 74) between 6.8 and 8 years. Total costs increased from $37,100 among people not receiving total knee arthroplasty to $57,900 per person undergoing total knee arthroplasty, resulting in a cost-effectiveness ratio of $18,300 per quality-adjusted life year. Based on those findings, total knee arthroplasty appears to be a highly cost-effective procedure for the management of end-stage knee osteoarthritis, compared with nonsurgical treatments, and within the range of accepted cost-effectiveness for other musculoskeletal procedures, researchers say.

"This result is robust across a broad range of assumptions regarding both patient risk and hospital volume," they wrote in the published report. "For patients who choose to undergo total knee arthroplasty, hospital volume plays an important role: Regardless of patient risk level, higher-volume centers consistently deliver better outcomes. But the additional survival benefits associated with high-volume centers provide limited cost-effectiveness benefits for high-risk patients deliberating between medium- and high-volume centers." Even procedures performed in low-volume centers were more cost-effective than not having total knee arthroplasty, regardless of the patient's risk of complications.

"Clinicians, patients, and policy makers should consider the relative cost-effectiveness of total knee arthroplasty in making decisions about who should undergo total knee arthroplasty, where and when," the researchers concluded.

In an editorial, Stephen Lyman, of Cornell University's Weill Medical College, and colleagues, wrote, "Although total knee arthroplasty is a safe and effective treatment for advanced knee osteoarthritis, lingering questions remain regarding variations in patient outcomes due to differences among patients undergoing the procedure and among the hospitals where it is performed."

They noted that the cost-effectiveness ratio of $18,300 per quality-adjusted year "falls below the cost-effectiveness thresholds often mentioned as appropriate," such as the threshold of roughly $29,000 to $44,000 per year used by the British National Health Service's National Institute for Health and Clinical Excellence.

Analyses such as the one Losina and her colleagues conducted "highlight several of the dilemmas policy makers face in evaluating widely used medical technologies," they concluded. "At least in the U.S., even well-performed cost-effectiveness analyses do not influence either payers or physicians directly. Payers do not use the results to make coverage determinations nor do physicians use them to make treatment decisions. How we move from this current state to a system in which cost-effectiveness of procedures affects medical practice is unclear."

This research was supported in part by grants from the National Institutes of Health, the National Institute of Arthritis and Musculoskeletal and Skin Diseases, and the Arthritis Foundation.