Table 1.

Outcome groups for the FNIH OA Biomarker cohort.

Group Description§	Participants in full dataset	Participants in current study
Primary Cases
1. Knees with both radiographic and pain progression	194	173
Controls#
2. Knees with radiographic but not pain progression	103	91
3. Knees with pain but not radiographic progression	103	89
4. Knees with neither radiographic nor pain progression	200	174

^#Controls were made up of participants who met all eligibility criteria to be cases except the concurrent radiographic and symptomatic progression criteria.

^§If both knees of a participant were in one group, one was randomly selected as the index knee for study inclusion. Participants with one knee displaying only radiographic progression and the other knee only pain progression were excluded. Knees selected for the four groups were frequency matched to the extent possible using KLG strata 1–3 and body mass index strata <25, 25–27.5, 27.5–30, 30–35, ≥35kg/m². Group 4 knees could not have radiographic progression, including worsening of lateral compartment JSN, or pain progression in the contralateral knee.

F, females; M, males