Study shows cost-effectiveness of total knee replacement for patients with knee osteoarthritis

Knee osteoarthritis is a painful condition that affects over 14 million U.S. adults, many of whom have extreme obesity, defined by body mass index (BMI) greater than 40kg/m². Total knee replacement (TKR) is often recommended to treat advanced knee osteoarthritis, but surgeons may be hesitant to operate on patients with extreme obesity due to concerns about the increased risks of tissue infection, poor wound healing and higher risk of implant failure.

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 TKR. They found that across older and younger age groups, TKR is a cost-effective treatment for these patients. Findings are published in Annals of Internal Medicine.

"People with extreme obesity experience substantial pain reduction from TKR, leading to meaningful improvements in quality-adjusted life expectancy. High BMI should not serve as a barrier for people seeking this procedure," 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's Orthopedic and Arthritis Center for Outcomes Research. "From a health policy perspective, this operation offers a very good value for the dollars spent."

The computer model used by the researchers, OAPol, combines clinical and economic data from national datasets to forecast the clinical course of patients who decide to receive or forgo TKR. In the model, each treatment choice is 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 TKR, calculated as dollars for quality adjusted life year (QALY) gained. The researchers reported favorable cost-effectiveness ratios of $35,200 and $54,100 per QALY for patients younger and older than 65 years, respectively. The researchers noted that most patients with extreme obesity and advanced knee osteoarthritis considering TKR are in the younger age range. These data, they suggest, may help to diminish concerns regarding the value of TKR in these patients.

Instead of questioning whether or not to do surgery for people with extreme obesity, the conversation should be about how to accommodate these patients and provide accurate information about what to expect post-surgery. 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 TKR in these patients."

Elena Losina, Co-Director, Brigham's Orthopedic and Arthritis Center for Outcomes Research