Younger People Increasingly Vulnerable to Knee Osteoarthritis

The number of Americans diagnosed with knee osteoarthritis (OA) will increase dramatically over the next decade, and the average age at which they are diagnosed will drop, a new study finds. The study, based on computer modeling of data from the Centers for Disease Control and Prevention, was presented earlier this month at the annual scientific meeting of the American College of Rheumatology in Chicago.

The study found that 6.5 million Americans between the ages of 35 and 84 will be diagnosed with knee OA over the next decade, and that 59% of the newly diagnosed patients will be between the ages of 45 and 64. It also found that 4.8% of Americans between the ages of 45 and 54 will be diagnosed with knee OA over the next decade, compared with just 1.5% of Americans between the ages of 45 and 54 in the 1990s. This increase in cases among younger Americans will drive the average age of knee OA diagnosis down from 72 in the 1990s to 56 in the 2010s.

“In the last decade, obesity and knee injuries have become more prevalent, possibly contributing to the increase in knee OA in younger adults,” said senior study author Elena Losina, PhD, co-director of the Orthopedics and Arthritis Center for Outcomes Research at the Brigham and Women's Hospital in Boston. “These trends toward earlier knee OA diagnosis may have a dramatic economic impact on the US health care system.”

Losina and her colleagues used data from the CDC in a computer model of the course of knee OA to estimate the number of newly diagnosed cases in the US in the 1990s and the 2010s. The model allowed them to simulate the onset and progression of knee OA in individuals with demographic characteristics similar to the US population from age 25 to death. Data from the model were combined with CDC population estimates to project the incidence and course of knee OA in the US during the time periods studied.