Is symptomatic knee osteoarthritis a risk factor for a trajectory of fast decline in gait speed? Results from a longitudinal cohort study.

Objective: Gait speed is an important marker of health in adults and slows with aging. While knee osteoarthritis (OA) can result in difficulty walking, it is not known if radiographic knee OA (ROA) and/or knee pain are associated with a fast decline trajectory of gait speed over time.
Methods: Gait speed trajectories were constructed using a multinomial modeling strategy from repeated 20-meter walk tests measured annually over 4 years among participants from the Osteoarthritis Initiative, a prospective cohort study of adults ages 45-79 years at baseline with or at high risk of knee OA. We grouped participants into 4 knee OA categories (having neither ROA nor knee pain, ROA only, knee pain only, or symptomatic knee OA [ROA and pain]) and examined their association with trajectories of gait speed using a multivariable polytomous regression model adjusting for age and other potential confounders.
Results: Of the 4,179 participants (mean ± SD age 61.1 ± 9.1 years, 57.6% women, mean ± SD body mass index 28.5 ± 4.8 kg/m(2) ), 5% (n = 205) were in a fast decline trajectory, slowing at a rate of 2.75%/year. People with symptomatic knee OA had an almost 9-fold risk (odds ratio 8.9; 95% confidence interval [95% CI] 3.1, 25.5) of being in a fast decline trajectory compared with those with neither pain nor ROA. Participants with knee pain had 4.5 times the odds of a fast decline (95% CI 1.4, 14.6), and those with ROA only had a slight but non-statistically significant increased risk.
Conclusion: People with symptomatic knee OA have the highest risk of a fast decline trajectory of gait speed compared with people with ROA or pain alone.
(Copyright © 2013 by the American College of Rheumatology.)