Lifetime Risk of Knee Osteoarthritis

Washington, DC—Black females are at the greatest lifetime risk of being diagnosed with and needing a total knee replacement (TKR) for knee osteoarthritis (OA), investigators reported in a study presented at the ACR meeting that looked at race and sex as key factors in knee OA in the United States.

The study also found that black females followed by Hispanic women are at the highest risk of developing symptomatic OA relatively young. According to Elena Losina, PhD, the study’s lead author and co-director of the Orthopedic and Arthritis Center for Outcomes Research at Brigham and Women’s Hospital in Boston, Massachusetts, this suggests the need to promote awareness of OA risk earlier to improve prevention.

One way to reduce the lifetime risk of OA suggested by the study, she said, is to develop race and sex-tailored weight management programs, as obesity increases the risk of knee OA and black and Hispanic women have a greater likelihood of being obese.

These conclusions are based on a study in which Dr. Losina and colleagues used published data on the incidence of OA along with a validated computer simulation model, called the Osteoarthritis Policy (OAPol) model, to estimate the 10-year, 20-year, 30-year, and lifetime risk of being diagnosed with symptomatic knee OA and treatment with TKR from age 40, stratified by race and sex.

Data used in the model came from published studies on the incidence of OA stratified by sex and obesity. These data showed that obesity prevalence ranged from 19% for white males to 34% for black females. Rates of progression of knee OA were derived from the Johnston County Osteoarthritis Project, a multicenter-sponsored project that studies OA of the hip and knee in Johnston County in North Carolina, and calibrated to the published data.

Data from 2 national longitudinal studies of persons with knee OA, (1) the Multicenter Osteoarthritis Study and (2) the Osteoarthritis Initiative, were used to estimate the annual incidence of TKR among persons with advanced knee OA (ie, Kellgren-Lawrence grade 3 or 4 disease). National survey data and published data also provided input parameters for the model on mortality, obesity, comorbidities, nonsurgical OA treatments, and implant failure.

The study found that the lifetime risk of being diagnosed with symptomatic knee OA in people without knee OA at age 40 ranged from 10% among white males to 17% among black females. The 20-year risk ranged from about 6% in males (race or ethnicity did not affect this rate in males) to 8% in black females. 

By age 65, the study found that black females, followed by Hispanic females, without knee OA at age 40, had the highest risk of being diagnosed with symptomatic OA—black females had an  11.3% risk, Hispanic females a 10.5% risk, and white females a 10.0% risk.

Black females also were found to have the highest lifetime need for TKR, with the lifetime need for TKR ranging from 3.8% for Hispanic males to 6.8% for black females.

Given that obesity is a known risk factor of developing knee OA, and published data show higher rates of obesity in black and Hispanic women, Dr. Losina said that the study suggests that prevention strategies that focus on increasing physical activity and managing weight may be more effective if tailored to each unique population group.