Table 2.
Biomarker levels in each subgroup of the subjects according to the radiographic classification
| Radiographic OA | Mean | SE | 95% CI of the mean | P-value | 95% CI for difference | ||
|---|---|---|---|---|---|---|---|
| Lower | Upper | ||||||
| sC2C | K/L1 | 5.56 | 0.04 | 5.49 | 5.64 | 0.06 | -0.09 to 0.30 |
| Ln (pmol/ml) | K/L2 | 5.42 | 0.07 | 5.29 | 5.55 | ||
| sCPII | K/L1 | 7.53 | 0.06 | 7.38 | 7.64 | <0.01* | 0.26 to 0.78 |
| Ln (ng/ml) | K/L2 | 6.99 | 0.11 | 6.77 | 7.21 | ||
| uCTX-II/Cr | K/L1 | 5.25 | 0.13 | 4.99 | 5.52 | 0.15 | -0.94 to 0.15 |
| Ln (ng/μmol creatinine) | K/L2 | 5.65 | 0.23 | 5.19 | 6.11 | ||
| sC2C/sCPII | K/L1 | 0.14 | 0.02 | 0.10 | 0.18 | <0.01* | -0.21 to -0.04 |
| K/L2 | 0.26 | 0.04 | 0.19 | 0.34 | |||
| uCTX-II/sCPII | K/L1 | 0.11 | 0.06 | -0.01 | 0.22 | <0.01* | -0.68 to -0.22 |
| K/L2 | 0.56 | 0.10 | 0.37 | 0.75 | |||
| uNTx/Cr | K/L1 | 3.79 | 0.10 | 3.60 | 3.98 | 0.10 | -1.47 to -0.59 |
| Ln (ng/ml creatinine) | K/L2 | 3.46 | 0.16 | 3.13 | 3.79 | ||
| sHA | K/L1 | 2.97 | 0.12 | 2.74 | 3.21 | <0.01* | -1.21 to -0.27 |
| Ln (pmol/ml) | K/L2 | 3.71 | 0.20 | 3.31 | 4.11 | ||
All analyses were adjusted for age, gender, and body mass index. The urinary biomarkers were corrected for creatinine. The number of subjects with K/L grade 1 was 30, while that with K/L grade 2 was 16. *P-values less than or equal to 0.05 are statistically significant. 95% CI, 95% confidence interval; C2C, cartilage collagen type II cleavage; CPII, cartilage type II collagen carboxy propeptide; CTX-II, type II collagen C-telopeptide; HA, hyaluronic acid; K/L, Kellgren-Lawrence grade; Ln, natural log; NTx, N-terminal crosslinking telopeptide of type I collagen; SE, standard error of the mean; s, serum; u, urine.