Does the one-year decline in walking speed predict mortality risk beyond current walking speed in adults with knee osteoarthritis?

Objective To investigate whether walking speed at one time-point, decline over the past one year, or both predict mortality risk over 11 years in adults with or at risk of knee osteoarthritis (OA). Methods Using the data from the Osteoarthritis Initiative, we defined slow vs. adequate walking speed as walking 0.08 m/s over past one year. At the 12-month visit, we classified adequate sustainers as those with adequate walking speed and no meaningful decline, slow sustainers as slow walking speed and no meaningful decline, adequate decliners as adequate walking speed and meaningful decline, and slow decliners as slow walking speed and meaningful decline. Mortality was recorded over 11 years. To examine the association of walking speed with mortality, hazard ratios and 95% confidence intervals (HR[95%CI]) were calculated using Cox regression, adjusted for potential confounders. Results Of 4229 participants in the analytic sample (58% female, age 62±9 years, BMI 29±5 kg/m2), 6% (n=270) died over 11 years. Slow sustainers and slow decliners had two times increased mortality risk compared to adequate sustainers (HR[95%CI]; 1.96[1.44, 2.66] for slow sustainers, and 2.08[1.46, 2.96] for slow decliners). Adequate decliners had 0.43 times the mortality risk compared with adequate sustainers (0.57[0.32, 1.01]). Conclusion In adults with or at risk of knee OA, walking slower than