Sharma L, Kwoh K, Lee JJ, et al. - A total of 1,870 (derivation) and 1,279 (validation) people were involved in order to generate and verify risk stratification trees for incident slow gait in persons at high risk for knee OA, feasible in community and clinical settings. The most frugal tree recognized three risk groups, from stratification on the basis of age and WOMAC Function. A 7-risk-group tree also involved education, vigorous sport/recreational activity, obesity and depressive symptoms and outcome occurred in 11%, varying 0%–29% (derivation) and 2%–23% (validation) depending on the risk group. AUCs were similar in the two cohorts. Therefore, in individuals at high risk for knee OA, easily acquired data can be utilized to recognize those at high risk of incident functional impairment. Outcome risk differed considerably depending on tree-based risk group membership. These trees can notify individual awareness of risk for impaired function and clarify qualification for prevention trials.