Joint Replacement in Seniors Reduces Pain and Increases Independence

Newswise — Total joint replacement may reduce pain and disability in senior citizens with arthritis, according to research presented this week at the American College of Rheumatology Annual Scientific Meeting in Boston, Mass.

Arthritis is the number one cause of disability in senior citizens and the most common reason for hip and knee replacement. Over the past several years, studies have documented an approximately two percent annual reduction in the amount of disability affecting the population over the age of 65 years. It's not clearly understood why senior citizens are less disabled than in the past.

Researchers recently conducted a series of thought exercises (which use a hypothetical scenario to study reality) to estimate the impact of total joint replacement on national disability in senior citizens over the age of 65.

These thought exercises were completed by combining estimates of the 1-year impact of TJR on disability in senior citizens as measured by the Health Assessment Questionnaire (HAQ, a measure of functional ability in which patients assess themselves) with estimates of the increasing use of hip and knee replacements across the U.S.

483 patients who underwent TJR were selected from the Arthritis, Rheumatism, and Aging Medical Information System, and researchers reviewed their pre-and-post surgery HAQ scores.

The results showed that TJR offers improvement in HAQ scores and an approximate 20 percent reduction of pain at 1-year after surgery. After reviewing the results, researchers were able to conclude that increasing TJR use accounts for approximately four to five percent 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 Eliza Chakravarty, MD, MS; assistant professor, 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."

The ACR is an organization of and for physicians, health professionals, and scientists that advances rheumatology through programs of education, research, advocacy and practice support that foster excellence in the care of people with or at risk for arthritis and rheumatic and musculoskeletal diseases. For more information on the ACR's annual meeting, see http://www.rheumatology.org/annual.

Editor's Notes: James F. Fries, MD, will present this research during the ACR Annual Scientific Meeting at the Boston Convention and Exhibition Center from 4:30 " 6:00 pm ET on Saturday, November 10, 2007, in Room 156. Dr. Eliza Chakravarty will be available for media questions and briefing at 1:30 pm ET on Thursday, November 8 in the on-site press conference room, Room 251.

Presentation Number: 2114

Total Joint Replacement Contributes to Declining Disability Rates in Seniors

James F. Fries, Eliza F. Chakravarty, Bharathi Lingala, Helen B. Hubert. Stanford University, Palo Alto, CA

Purpose: Arthritis is the most common cause of senior disability and the most common reason for hip and knee replacement. Total joint replacement (TJR) improves physical function and pain without large effects on mortality. Since 1982 multiple studies in the U. S. have documented a steady decline in disability over age 65, of approximately 2% annually in recent years. We sought to estimate the fraction of the national disability reduction attributable to TJR.

Methods: We conducted a series of thought exercises to estimate the magnitude of increased use of TJR upon the decreasing national disability by combining estimates of the 1- year impact of TJR upon disability in subjects over 65 years as measured by the Health Assessment Questionnaire (HAQ) in senior individuals with estimates of the increasing incidence of hip and knee replacements across the population. Underlying assumptions included: (a) the 1-year reduction in HAQ from TJR lasts 10 years, thus the prevalence is ten times the incidence, (b) the mortality rate of TJR is negligible; and (c) the benefit from individual TJR procedures was constant from 1982-2004. Rates of TJR in 1982 and 2004 were derived from the National Hospital Discharge Survey. HAQ scores before and 1-year after TJR were directly computed from the ARAMIS database.

Results: The ARAMIS database contains 483 subjects with RA and OA who had undergone TJR with pre-and post-HAQ scores. Baseline HAQ scores pre-TJR were 1.5. The mean decrease in HAQ was 0.057 from baseline. Among 1361 comparison subjects without TJR, mean increase in HAQ was approximately 0.043 annually, the age effect. In a nested case-control study, forty-seven subjects with TJR 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. Pain reductions at 1 year were about 20%. Age and gender adjusted rates of TJR were 4.5 per1000 seniors in 1982 and 16.5 per 1000 in 2004.

If 1.6% of the senior population undergoes TJR annually, and the anticipated improvement in HAQ is 0.10-0.15 units, then over a 10-year period, 16% of seniors will have a reduction of 7% in disability while 84% will have no associated change in disability accrual. Thus, the population attributable benefit of TJR may be estimated at 0.11 % per year, representing about 4 to 5% of the national disability decline. The most problematic assumption, for which we could find no data, is the duration of improvement in function post-TJR. If the initial benefit from TJR is linearly lost over 10 years due to competing risks, then the estimated disability reduction would be halved.

Conclusions: TJR results in a modest but definite benefit in disability for the patient, and a greater benefit in pain relief. The nearly 4-fold increase in TJR among seniors since 1982 has made a positive contribution to declines in national disability rates.

Disclosure Block: J.F. Fries, None; E.F. Chakravarty, None; B. Lingala, None; H.B. Hubert, None.