Baseline characteristics of JOS-C study participants at the time of JOS study exit (age 6 y)
| Baseline characteristics at age 6 y . | Early prophylaxis . | Delayed prophylaxis . | P . |
|---|---|---|---|
| Participants in analysis, n | 15 | 18 | |
| Age of prophylaxis initiation, mean (SD), y | 1.3 (0.4) | 7.6 (3.5) | <.0001 |
| MRI OC damage, n/N (%) | |||
| Boys with OC damage | 1/15 (6.7) | 9/18 (50) | .020 |
| Joints with OC damage | 1/89 (1) | 9/102 (9) | .021 |
| No MRI damage, eMRI score < 1, n/N (%) | |||
| Boys with no damage | 11/15 (73) | 6/18 (33) | .022 |
| Joints with no damage | 85/89 (96) | 81/102 (79) | .001 |
| eMRI, median (IQR) of participant joint averages | |||
| MRI score | 0.08 (0-0.3) | 0.6 (0.02-1.7) | .07 |
| OC MRI score | 0 (0-0) | 1.2 (0.3-3.1) | .05 |
| ABR prior to age 6 y, mean (SD) | |||
| Joint ABR | 0.7 (0.8) | 3.8 (2.8) | .0002 |
| ABR | 3.2 (3.1) | 14.4 (6.6) | .0072 |
| CPJAS, average per joint, mean (SD) | |||
| Physical examination score | 1.0 (0.9) | 1.7 (1.4) | .094 |
| Baseline characteristics at age 6 y . | Early prophylaxis . | Delayed prophylaxis . | P . |
|---|---|---|---|
| Participants in analysis, n | 15 | 18 | |
| Age of prophylaxis initiation, mean (SD), y | 1.3 (0.4) | 7.6 (3.5) | <.0001 |
| MRI OC damage, n/N (%) | |||
| Boys with OC damage | 1/15 (6.7) | 9/18 (50) | .020 |
| Joints with OC damage | 1/89 (1) | 9/102 (9) | .021 |
| No MRI damage, eMRI score < 1, n/N (%) | |||
| Boys with no damage | 11/15 (73) | 6/18 (33) | .022 |
| Joints with no damage | 85/89 (96) | 81/102 (79) | .001 |
| eMRI, median (IQR) of participant joint averages | |||
| MRI score | 0.08 (0-0.3) | 0.6 (0.02-1.7) | .07 |
| OC MRI score | 0 (0-0) | 1.2 (0.3-3.1) | .05 |
| ABR prior to age 6 y, mean (SD) | |||
| Joint ABR | 0.7 (0.8) | 3.8 (2.8) | .0002 |
| ABR | 3.2 (3.1) | 14.4 (6.6) | .0072 |
| CPJAS, average per joint, mean (SD) | |||
| Physical examination score | 1.0 (0.9) | 1.7 (1.4) | .094 |
Numbers expressed as mean (SD) or median (IQR) for continuous variables depending on normal or skewed distribution, and number (percentage) for count variables. Maximum CPJAS score, 31 points per joint; maximum MRI score, 45 per joint; maximum OC score, 36 per joint.
OC, osteochondral.