Table 2 

Biomarker levels in each subgroup of the subjects according to the radiographic classification 

Radiographic OA 
Mean 
SE 
95% CI of the mean 
Pvalue 
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 

uCTXII/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 

uCTXII/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. *Pvalues 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; CTXII, type II collagen Ctelopeptide; HA, hyaluronic acid; K/L, KellgrenLawrence grade; Ln, natural log; NTx, Nterminal crosslinking telopeptide of type I collagen; SE, standard error of the mean; s, serum; u, urine. 

Ishijima et al. Arthritis Research & Therapy 2011 13:R22 doi:10.1186/ar3246 