Total knee replacement (TKR) for the treatment of advanced knee osteoarthritis is an efficacious and cost-effective treatment, even for people with extreme obesity (defined as having a body mass index, or BMI, of 40 or higher). This finding from experts at Brigham and Women’s Hospital was published recently in the Annals of Internal Medicine.
“Total knee replacement is one of the best medical advancements of the 20th century, reducing pain and helping people gain functional status and become more active in their day-to-day lives,” said corresponding author Elena Losina, PhD, co-director of the Brigham’s Orthopaedic and Arthritis Center for Outcomes Research and a founding director of the Policy and Innovation eValuation in Orthopaedic Treatments Center.
“The challenge is that knee osteoarthritis disproportionally affects people who have extreme obesity,” she added. “Many surgeons are hesitant to offer the procedure because of their concerns about complications in this patient population.”
The goal of the study was to help inform physicians, policymakers and patients about the long-term clinical benefits and value of the procedure.
OAPol Computer Model Aids in Analysis
To perform their analysis, investigators used a computer simulation called the Osteoarthritis Policy (OAPol) Model, which was developed by a multicenter team that Dr. Losina leads. The OAPol model has been continuously funded by the National Institute of Arthritis and Musculoskeletal and Skin Diseases since 2006.
“The goal of this type of research is to capture all the long- and short-term benefits and the detriments of a specific medical procedure over a timeframe that is meaningful,” Dr. Losina said. “Because a total knee replacement lasts decades in most cases, a computer simulation is a good way to help evaluate this procedure over its long-lasting timeline.”
The analysis looked at the benefits, risks and costs of TKR surgery. The primary benefit noted was pain reduction. The potential risks involved postsurgical complications, including pulmonary embolism, pneumonia, deep vein thrombosis and infection. Investigators also looked at the cost of the procedure and the dollar value of the quality-adjusted life years (QALY) gained. This measure accounts for factors like workdays lost due to pain or other complications of illness.
The analysis found favorable cost-effective ratios of $35,200 per QALY for patients aged 65 and under and $54,100 per QALY for those over age 65. Most patients with extreme obesity develop advanced knee osteoarthritis earlier in their lives and consider surgery earlier compared to patients with similar stages of knee osteoarthriris who don’t have extreme obesity. That is why the researchers conducted analysis for different age groups.
In addition, CMS is the most likely payer for those over age 65, while those younger than 65 are more likely to be covered by commercial insurances. The analysis provided valuable data for both types of payers.
“There are plenty of interventions that cost a lot but provide little benefit. Our study showed that despite being costly, this procedure provides a very good value,” Dr. Losina said. “As a society, it’s important to promote good value care and reduce wastage of health care resources.”
Weighing Benefits and Risks of TKR
Dr. Losina explained that although the rates of surgical and postsurgical complications are higher in people with obesity, because overall complication rates are so low, even a two- or three-fold increase means this operation is still very safe overall.
“But it’s still important to recognize the challenges,” she noted. “Patients with BMIs over 50 may be so heavy that equipment in some operating rooms may not be suitable. Especially in nonacademic settings, if surgeons don’t feel comfortable operating on these patients, they may want to refer these more challenging cases to an academic medical center. Ideally it would be helpful for these patients to try to lose weight, but it may be difficult to achieve without rigorous, structured weight-reduction programs.”
Richard Iorio, MD, chief of the Adult Reconstruction and Total Joint Arthroplasty Service and Vice Chairman for Clinical Effectiveness at the Brigham, said that he “applauds Dr. Losina and her team for their pioneering work concerning the cost-effectiveness of TKA in those with extreme obesity.”
He explained that several patient demographic factors and medical comorbidities may lead to increased episode-of-care costs. When combined, they can lead to complication rates that are orders of magnitude higher. Most of these factors are nonmodifiable, but others can be optimized before surgery, he noted.
“It is unfortunate that hospitals and surgeons are judged by short-term complication rates instead of a 20- to 30-year horizon for determining success or failure,” Dr. Iorio said. “If episode-of-care length is changed to reflect the true survivorship of the operation, we may be able to ultimately prevent problems with access to care for high-risk patients.”
As Dr. Losina concluded, it’s all about improving patients’ lives. “Orthopaedic surgeons want nothing but the best for their patients,” she said. “We hope this study will help to facilitate the availability of this procedure in those who need it.”