Background/Purpose: Poorer physical functioning as a single baseline measurement has been associated with increased risk of radiographic knee osteoarthritis (rKOA) progression, but it is unknown whether reduced physical functioning as well as its change over time is associated with rKOA progression. Slower walking speed, suggestive of decreased physical functioning, or reductions in walking speed may be an early indicator of worsening osteoarthritis or contribute to underlying disease advancement.

Methods: We analyzed Johnston County Osteoarthritis Project data from baseline (1999-2004) and up to three follow up visits (2006-2010; 2013-2015; 2017-2018). Walking time was evaluated over an 8-foot walk distance in two trials; walking speed was calculated as the average of the trials and log-transformed. Progression of rKOA was defined as an increase of one Kellgren-Lawrence (K-L) grade or more in at least one knee between two visits. A joint statistical model (JM), incorporating a linear mixed effects model for repeated walking speed measures and a Cox proportional hazards model for time-to-event outcome of K-L grade increase, was used to evaluate the association between longitudinal walking speed measures and rKOA progression. Two separate JMs were run evaluating 1) change in walking speed (slope) over time (model 1) and 2) current walking speed adjusting for the slope (model 2) on risk of K-L grade increase. Both models were adjusted for sex, race, education, BMI and age at baseline.

Results: Our final sample consisted of 1,606 participants with at least one measurement of walking speed and a minimum of two visits with knee radiographs (average follow-up time was 8 ± 3 years). At baseline, mean age was 62 ± 9 years, over two-thirds of participants were women (67%), and mean walking speed was 3.5 ± 1.8 seconds per 8-foot walk distance. During follow-up, 1,077 (67%) participants had rKOA progression in at least one knee. Application of JM demonstrated model 2 incorporating both the current level and slope of walking speed had the best model fit (model 1 Bayesian Information Criterion [BIC] 6767 vs. model 2 BIC 5661). In model 2, slower current walking speed but not slope was associated with rKOA progression adjusted for sex, race, education, BMI and age at baseline. Specifically, a 50% slower walking speed was associated with 2-fold higher risk for progression (hazard ratio [HR] = 1.99; 95% CI, 1.08-3.67).

Conclusion: rKOA progression is associated with an individual’s current level of walking speed and not on the reduction in walking speed over time. Treatment and interventions for individuals with knee OA aimed at improving physical function may help maintain or increase walking speed and slow rKOA progression regardless of the rate of decline.

« Back to ACR Convergence 2020

ACR Meeting Abstracts - https://acrabstracts.org/abstract/slower-current-walking-speed-is-associated-with-progression-in-radiographic-knee-osteoarthritis-the-johnston-county-osteoarthritis-project/