BOSTON, Massachusetts—Total joint replacement (TJR) has reduced pain and disability in elderly patients with arthritis. The procedure is cost-effective even for high-risk patients, but it is associated with higher risk for cardiac complications if both joints are replaced during the same procedure, and it might be chosen by more African-American patients if finances were less of an issue, according to studies reported at the American College of Rheumatology 2007 meeting.¹

TJR accounts for about 4% of decrease in seniors' disability

Over the past several years, studies have documented an approximately 2% annual reduction in the amount of disability affecting the population >65 years. James F. Fries, MD, Eliza F. Chakravarty, MD, and colleagues from Stanford University, Palo Alto, California, reported that a small but significant part of that improvement—about 5%—can be attributed to TJR.

The researchers combined estimates of the 1-year impact of TJR on disability in senior citizens as measured by the Health Assessment Questionnaire (HAQ) with estimates of the increasing use of hip and knee replacements across the US. They reviewed pre- and post-surgery HAQ scores for 483 TJR recipients with rheumatoid arthritis or osteoarthritis from the Arthritis, Rheumatism, and Aging Medical Information System (ARAMIS) database. The TJR subjects were compared with 1361 subjects without TJR.

Baseline HAQ pre-TJR was 1.5. The mean decrease in HAQ was 0.057 in TJR recipients (vs a HAQ increase of 0.043 in subjects without TJF). The review also showed an approximate 20% reduction of pain at 1 year after surgery.  After reviewing the results, researchers were able to conclude that increasing TJR use accounts for approximately 4% of the national decline in disability among senior citizens.

"We were surprised that the impact of pain was so impressive, even over that of the change in disability in people who have had a joint replacement," said Dr. Chakravarty, assistant professor at Stanford University School of Medicine, and investigator in the study. "This data would not be captured in the nationwide observations of the decline in disability over the past few decades, but is consistent with our clinical observations of the dramatic effect of pain relief associated with total joint replacement." Dr. Chakravarty noted that the numbers of TJRs increased from 4.3/1000 population in 1982 to 16.5/1000 in 2004.

The researchers estimated the magnitude of increased use of TJR upon the decreasing national disability by combining estimates of the 1-year impact of TJR on disability in subjects over 65 years of age as measured by the HAQ with estimates of the incidence of hip and knee replacements across the population. They assumed that the 1-year reduction in HAQ from TJR lasts 10 years, that the mortality rate of TJR is negligible, and that the benefit from individual TJR procedures was constant from 1982 to 2004.

The researchers also conducted a nested case-control study in which 47 subjects with TJR each had a control matched for age, gender, and HAQ-DI. "After 1 year, TJR subjects had a decrease in HAQ of 0.125 while matched controls had an increase of 0.018. Together, these results suggest that TJR yields a first year improvement of approximately 0.10 to 0.15 HAQ units, or about 7% reduction from baseline," Dr. Chakravarty said.

The investigators estimated that if 1.6% of the senior population undergoes TJR annually, and the anticipated improvement in HAQ is 0.10 to 0.15 units, it is presumed that over a 10-year period, 16% of seniors will have a reduction of 7% in disability. The population-attributable benefit of TJR was estimated at 0.11% per year, representing about 4% to 5% of the national disability decline.

Even high-risk patients benefit from knee replacement

In related work, Elena Losina, PhD, and colleagues at Brigham and Women's Hospital in Boston found that total knee replacement (TKR) is cost-effective for the treatment of endstage arthritis, even for high-risk patients.²

The researchers used a computer simulation model of treatment options to weigh the costs of living with endstage arthritis and the costs of TKR against the potential improvements in both life expectancy and quality of life after TKR. This provided them with an estimate of the net cost per extra quality adjusted year of life gained (cost-effectiveness) from TKR.

TKR increased quality-adjusted life expectancy by 2.5 quality-adjusted life years (QALYs). Lifetime costs averaged $29,000 for patients with endstage knee arthritis who did not have TKR and $41,500 for similar patients who did have TKR, resulting in a cost-effectiveness ratio of $5300/QALY. Even "high risk" patients with multiple medical problems gained an additional 2.1 QALYs, with the cost-effectiveness of $7000 per quality adjusted year gained.

"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," Dr. Losina commented. "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."

Minimizing cardiac complications of TJR

Bilateral surgery (having both joints replaced during the same procedure) and revision surgery are independent risk factors for cardiac complications in patients having TJR, Jeffrey N. Katz, MD, and colleagues reported.³ This study also confirmed previously documented risk factors, including older age, and a history of cardiac problems had been previously recognized as associated with cardiac problems following surgery.

Dr. Katz and colleagues at Brigham and Women's Hospital in Boston conducted a case-control study over a 3-year period that compared 209 patients who received an initial or a second TJR of the knee or hip at one institution and who had cardiac complications during their admission and compared them with TJR patients who did not have complications. Cardiac complications included heart attack, congestive heart failure, unstable angina, irregular heartbeat, or pulmonary embolism.

"Physicians caring for total joint replacement patients should be aware that those who have bilateral or revision surgery and those with cardiac histories, along with the elderly, are at higher risk and merit closer observation for cardiac complications," Dr. Katz said.

Unmet financial needs suspected of contributing to low rates of TKR in black arthritis patients

A study of financial, tangible, informational, and emotional social support in 193 Caucasian and 185 African-American TKR candidates found that nearly 20% had at least one unmet need.⁴ Financial, tangible, informational, and emotional unmet social support need rates were higher among African-American men and women compared with Caucasian men and women, but only financial support remained significantly different after adjusting for other factors.

"Among total knee replacement candidates, African-American men and women appear to be at risk for having increased unmet social support needs compared with Caucasian men and women," said Huan Justina Chang, MD, MPH, assistant professor of medicine and rheumatology at Northwestern University, Feinberg School of Medicine, in Chicago, and the lead investigator in the study. "The disparity in unmet social support needs between African-American and Caucasian men and women is particularly notable in the unmet financial need group. Future studies in this area should focus on whether there is a causal relationship between social support and timing of total knee replacement, and the direction of this relationship."

Risk of Cardiac Complications After Total Joint Replacement

Risk Factor	Odds Ratio
History of arrhythmia	2.6
History of CAD, MI, CHF, or valvular heart disease	1.5
Revision surgery	2.2
Bilateral surgery	3.5

Adapted from Losina E, et al. American College of Rheumatology Meeting, 2007. ²


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