Examining Timeliness of Total Knee Replacement Among Patients with Knee Osteoarthritis in the U.S. : Results from the OAI and MOST Longitudinal Cohorts

The relief of pain and the restoration of functional activities are the main outcomes of primary total knee arthroplasty for the treatment of osteoarthritis. This paper examines the preoperative predictors of pain and functional outcome at one and two years following total knee arthroplasty. Patients were recruited for a prospective observational study of primary total knee arthroplasty for the treatment of osteoarthritis from centers in the United States, the United Kingdom, and Australia. Research assistants recruited the patients and collected the clinical history and physical examination data preoperatively and at three, twelve, and twenty-four months postoperatively. The Western Ontario and McMaster University Osteoarthritis Index (WOMAC), Short Form-36 (SF-36), and demographic data were obtained by self-administered patient questionnaires. We recruited 860 patients and obtained one-year WOMAC data on 759 patients (88%) and two-year data on 701 (82%). The mean age was seventy years, and 59% of the patients were female. Using hierarchical regression models, we found that the most significant preoperative predictors of worse scores on the pain and function domains of the WOMAC scale and on the physical functioning domain of the SF-36 at one and two years postoperatively were low preoperative scores, a higher number of comorbid conditions, and a low SF-36 mental health score. After adjusting for these predictors, we found that the functional status of the patients from the United Kingdom was significantly worse than that of the patients from the other countries and the difference was clinically important at both the one-year and two-year follow-up examination (p < 0.0005). The mean WOMAC pain scores for the three countries were not significantly different at one year, and, although they were significantly different at two years (p = 0.025), the difference was not clinically important. Patients who have marked functional limitation, severe pain, low mental health score, and other comorbid conditions before total knee arthroplasty are more likely to have a worse outcome at one year and two years postoperatively. After adjusting for these predictors, it was found that patients from the United Kingdom had significantly worse functional outcomes but similar pain relief compared with those from the United States and Australia.

Total knee arthroplasty (TKA) relieves pain and improves quality of life for persons with advanced knee osteoarthritis. However, to our knowledge, the cost-effectiveness of TKA and the influences of hospital volume and patient risk on TKA cost-effectiveness have not been investigated in the United States. We developed a Markov, state-transition, computer simulation model and populated it with Medicare claims data and cost and outcomes data from national and multinational sources. We projected lifetime costs and quality-adjusted life expectancy (QALE) for different risk populations and varied TKA intervention and hospital volume. Cost-effectiveness of TKA was estimated across all patient risk and hospital volume permutations. Finally, we conducted sensitivity analyses to determine various parameters' influences on cost-effectiveness. Overall, TKA increased QALE from 6.822 to 7.957 quality-adjusted life years (QALYs). Lifetime costs rose from $37,100 (no TKA) to $57 900 after TKA, resulting in an incremental cost-effectiveness ratio of $18,300 per QALY. For high-risk patients, TKA increased QALE from 5.713 to 6.594 QALY, yielding a cost-effectiveness ratio of $28,100 per QALY. At all risk levels, TKA was more costly and less effective in low-volume centers than in high-volume centers. Results were insensitive to variations of key input parameters within policy-relevant, clinically plausible ranges. The greatest variations were seen for the quality of life gain after TKA and the cost of TKA. Total knee arthroplasty appears to be cost-effective in the US Medicare-aged population, as currently practiced across all risk groups. Policy decisions should be made on the basis of available local options for TKA. However, when a high-volume hospital is available, TKAs performed in a high-volume hospital confer even greater value per dollar spent than TKAs performed in low-volume centers.

There are large variations in the use of knee arthroplasty among Medicare enrollees according to race or ethnic group and sex. Are racial and ethnic disparities more pronounced in some regions than in others, and if so, why? We used all Medicare fee-for-service claims data for 1998 through 2000 to determine the incidence of knee arthroplasty according to Hospital Referral Region, sex, and race or ethnic group. A total of 430,726 knee arthroplasties were performed during the three-year study period. At the national level, the annual rate of knee arthroplasty was higher for non-Hispanic white women (5.97 procedures per 1000) than for Hispanic women (5.37 per 1000) and black women (4.84 per 1000). The rate for non-Hispanic white men (4.82 procedures per 1000) was higher than that for Hispanic men (3.46 per 1000) and more than double that for black men (1.84 per 1000). The rates were significantly lower for black men than for non-Hispanic white men in nearly every region of the country (P<0.05). For the Hispanic population and for black women, racial or ethnic disparities at the national level were due in part to geographic differences rather than to differences in the rates for different racial and ethnic groups within geographic areas. Residential segregation and low income levels contributed to racial and ethnic disparities in arthroplasty rates. In the Medicare population, the rate of surgical treatment for osteoarthritis of the knee varies dramatically according to sex, race or ethnic group, and region. These variations underscore the importance of geography and sex in determining racial or ethnic barriers to health care. Copyright 2003 Massachusetts Medical Society