Demographic characteristics of the study population at baseline grouped by mitochondrial DNA (mtDNA) haplogroups in the progression subcohort of the OAI.

Values are mean±standard deviation or number of patients with percentage in parentheses; OAI: osteoarthritis initiative; (*) Kruskal-Wallis non-parametric test for comparison between mtDNA haplogroups; (#) Chi-square test; BMI: body mass index; KL: Kellgren and Lawrence; mJSN: Joint space narrowing in medial compartment; (**) The worst knee and the less severe knee at baseline were designated, respectively, as the knee with the highest and lowest KL (Kellgren andLawrence) grade, OARSI JSN (joint space narrowing) grade, OARSI osteophytes grade or OARSI sclerosis grade, as appropriate on each case; significant p-values are in bold. Demographic characteristics of the study population at baseline grouped by mitochondrial DNA (mtDNA) haplogroups in the progression subcohort of the OAI.