TKA Is a Cost-Effective Treatment for Patients with OA and Morbid Obesity
Surgeons may be hesitant to perform total knee arthroplasty (TKA) in patients with morbid obesity (BMI of 40 Kg/m2 or more) – even if they have painful, debilitating end-stage osteoarthritis of the knee – due to concerns about higher rates of postoperative complications such as infection and poor wound healing.
However, a new study published in Annals of Internal Medicine shows that despite possible complications, TKA is cost-effective in these patients, offering them substantial improvement in quality-adjusted life expectancy, as well as good value for resources spent.
“People with [morbid] obesity experience substantial pain reduction from [TKA], leading to meaningful improvements in quality-adjusted life expectancy,” said corresponding author Elena Losina, PhD, a founding director of the Policy and Innovation eValuation in Orthopedic Treatments Center and a co-director of the Brigham and Women’s Orthopedic and Arthritis Center for Outcomes Research.
“High BMI should not serve as a barrier for people seeking this procedure. From a health policy perspective, this operation offers a very good value for the dollars spent.”
Obesity is a major risk factor for knee osteoarthritis, which affects more than 14 million adults in the United States. A growing proportion of patients who undergo TKA are obese, defined as a BMI of 30 kg/m2 or higher. In fact, 45.5% of patients who underwent TKA between 2006 and 2010 had a BMI between 30 and less than 40 kg/m2, and 14.8% had a BMI of 40 kg/m2 or more.Although TKA has been shown to be beneficial and cost-effective in non-obese patients with end-stage knee osteoarthritis, the question of whether TKA is cost-effective in patients with obesity had not been adequately addressed.
Using an established, validated, and widely published computer simulation called the Osteoarthritis Policy (OAPol) Model, researchers from Brigham and Women’s Hospital, together with collaborators from Yale and Boston University Schools of Medicine, quantified the tradeoff between the benefits and adverse events, taking into consideration costs of forgoing versus pursuing TKA based on clinical and economic data from national datasets.
In the model, each treatment choice was associated with benefits (improvements in pain leading to better quality of life), drawbacks (surgery complications, continuous pain reducing quality of life), and costs. The model tallies the data from a large number of patients to calculate an incremental cost-effectiveness ratio of TKA, calculated as dollars for quality adjusted life year (QALY) gained.
The investigators assessed the value of TKA in patients with morbid obesity across 2 age strata (younger than age 65 and older than age 65), as well as in the presence and absence of cardiovascular disease and diabetes, 2 major comorbidities that has been shown to increase the risk of perioperative complications.
They reported favorable cost-effectiveness ratios of $35,200 and $54,100 per QALY for patients younger and older than 65 years, respectively. The investigators noted that most patients with morbid obesity and advanced knee osteoarthritis who are considering TKA are in the younger age range. The data, they suggested, may help to diminish concerns regarding the value of TKA in these patients.
“Instead of questioning whether or not to do surgery for people with [morbid] obesity, the conversation should be about how to accommodate these patients and provide accurate information about what to expect post-surgery,” Dr. Losina said.
“Ultimately, this study raises the question of how to do the operation in a way that addresses all of the challenges that may arise. This is a discussion that should take place between individual patients and physicians, discussing all the risks, complications, and benefits as well as considerations of operating room accommodations that would optimize the work of orthopedic surgeons performing [TKA] in these patients.”
Chen AT, Bronsther CI, Stanley EE, Paltiel AD. The value of total knee replacement in patients with knee osteoarthritis and a body mass index of 40 kg/m2 or greater: a cost-effectiveness analysis. Ann Intern Med. 23 March 2021. https://doi.org/10.7326/M20-4722. Online ahead of print.