Study Shows Value of TKR in Virtually All Patients

Newswise — Total knee replacement is cost effective for the treatment of end-stage arthritis, even when treating high-risk patients, according to research presented this week at the American College of Rheumatology Annual Scientific Meeting in Boston, Mass.

When the knee is severely damaged by advanced arthritis and other treatment is not effective, total knee replacement may become an option. TKR removes worn cartilage and bone and resurfaces the knee with materials that function much like a normal joint.

By developing a computer simulation model of treatment options, researchers weighed the costs of living with end stage arthritis and the costs of TKR against the potential improvements in both quantity and quality of life resulting from the procedure. This provided them with an estimate of the net cost per extra quality adjusted year of life gained (cost-effectiveness) from TKR.

Researchers found that TKR can increase quality-adjusted life expectancy by two-and-a-half quality-adjusted life years (which take into account both the quality and quantity of years lived). In the absence of TKR, lifetime costs averaged $29,000 for patients with end-stage knee arthritis. For patients undergoing TKR, lifetime costs increased to $41,500, resulting in cost-effectiveness ratio of $5,300/QALY. Even for patients with multiple medical problems, 'high risk' TKR resulted in additional 2.1 quality-adjusted years, with the cost-effectiveness of $7,000 per quality adjusted year gained. There was substantial QALY gain in both high and low volume surgery centers.

Researchers explain that cost-effectiveness is a very different concept from cost-saving. Patients spend more money for TKR, but are doing more than finding a temporary fix—they are improving their quality of life, which goes beyond the price of surgery.

"We found that TKR represents an effective and very cost-effective option for all patients with knee arthritis, not just those whom we might label 'ideal' candidates," said Elena Losina, PhD, lead author of the study. "While it has been shown that higher volume facilities deliver better outcomes at lower cost, we would like to stress that TKR remains an attractive treatment option even in lower-volume settings. TKR delivers better value than many other widely accepted musculoskeletal procedures, such as lumbar discectomy and fusion of the spine for spondylolisthesis."

The American College of Rheumatology is the professional organization for rheumatologists and health professionals who share a dedication to healing, preventing disability and curing arthritis and related rheumatic and musculoskeletal diseases. For more information on the ACR's annual meeting, see http://www.rheumatology.org/annual.

Editor's Notes: Dr. Losina will present this research during the ACR Annual Scientific Meeting at the Boston Convention and Exhibition Center from 9:00 " 11:00 am ET on Thursday, November 8, 2007, in the Exhibit Hall.

Presentation Number: 84

Cost-Effectiveness of Total Knee Replacement (TKR) in the US: Impact of Patient Risk and Hospital Volume

Elena Losina1, Courtenay L. Kessler1, Rochelle P. Walensky2, Parastu S. Emrani1, William M. Reichmann1, Elizabeth A. Wright1, Daniel H. Solomon1, A. David Paltiel3, Edward Yelin4, Jeffrey N. Katz1. 1Brigham and Women's Hospital, Boston, MA; 2Massachusetts General Hospital and Brigham and Women's Hospital, Boston, MA; 3Yale University School of Medicine, New Haven, CT; 4University of California, San Francisco, San Francisco, CA

Background: Total knee replacement (TKR) is frequently performed to relieve pain and improve quality of life for persons with end-stage knee arthritis. The annual volume of TKR in the US exceeds 400,000. The cost-effectiveness of TKR in the US has not been examined carefully, nor have the economic consequences of hospital volume and individual perioperative risk.

Objective: To estimate cost-effectiveness of TKR for low- and high-risk patients with end-stage knee arthritis and to examine whether hospital volume influences cost-effectiveness assessments.

Methods: We developed a Markov state-transition computer simulation model of treatment options for end-stage knee arthritis. We conducted analyses for the overall population of US patients with end stage knee arthritis and three sub-populations: low, medium and high risk. Patient risk was defined based on the likelihood of perioperative complications. We considered four competing strategies for each group: no TKR and undergoing TKR in low-, medium-, and high-volume centers. Perioperative and longer-term outcomes of TKR were derived from Medicare claims and survey data from a national cohort of TKR recipients. Costs were derived from NHANES data, published literature and Medicare reimbursement schedules and expresseed in 2004 $US. Outcomes included quality-adjusted life expectancy, lifetime costs and cost-effectiveness ratios. Analysis was conducted from a societal perspective, using 3% annual discount rates. We performed a wide range of sensitivity analyses to identify parameters affecting cost-effectiveness.

Results: In the general population (mean age 73 years), TKR increased life expectancy from 4.2 to 6.7 quality-adjusted life-years (QALY) with lifetime costs increasing from $29,000 (no TKR) to $42,500 after TKR. The resulting cost-effectiveness ratio was $5,320/QALY. In the worst-case scenario (high risk patients receiving TKR in a low volume center) the cost-effectiveness ratio was $10,900/QALY. TKR in low-volume centers was a dominated strategy (higher cost, lower effectiveness) compared to having TKR in higher-volume centers. Results were most sensitive to improvement in quality of life after successful TKR, cost of TKR and cost of living with end-stage knee arthritis.

Conclusions: For persons with end-stage knee arthritis TKR is very cost-effective, even for high-risk patients and patients who undergo TKR in low-volume centers. The cost-effectiveness of TKR is comparable to the cost-effectivenss of ACL reconstruction, lumbar discectomy and total hip replacement, and lies well below established willingness-to-pay thresholds in the US.

Disclosure Block: E. Losina, None; C.L. Kessler, None; R.P. Walensky, None; P.S. Emrani, None; W.M. Reichmann, None; E.A. Wright, None; D.H. Solomon, None; A.D. Paltiel, None; E. Yelin, None; J.N. Katz, None.