Table 4

 Longitudinal regression analysis by generalised estimating equations for the relation between clinical variables of inflammation and biomarkers of joint destruction

Regression coefficient (RC)Standardised regression coefficient95% confidence interval of RCp Value
Model 4: lnCTX-I(or II)t  =  constant + a1.RF (0,1) + a2.treatment (0,1) + a3.RD (0,1) + b1.ESRt + b2.lnCTX-I(or II)t-1 + c1.t + c2.t2 (small letters in italics are regression coefficients: a refers to baseline variables (fixed); b refers to longitudinal variables (time dependent), and c refers to time variables. RF, rheumatoid factor (0 = absent; 1 = present); treatment (0 = sulfasalazine; 1 = COBRA); RD, radiographic damage at baseline (0 = absent; 1 = present); lnCTX-I(or II), the natural logarithm of CTX-I or CTX-II. See text for further explanations).
DAS28, 28 joint disease activity score.
(A) Collagen type 1 degradation (CTX-I)
ESR (mm)0.0120.05−0.01 to 0.0260.072
Swollen joint count (0–28)0.0370.04−0.019 to 0.0930.20
Tender joint count (0–28)0.0320.03−0.018 to 0.0810.22
DAS280.400.090.16 to 0.670.001
(B) Collagen type II degradation (CTX-II)
ESR (mm)0.00790.240.005 to 0.01<0.001
Swollen joint count (0–28)0.0210.170.011 to 0.031<0.001
Tender joint count (0–28)0.0070.08−0.001 to 0.0210.089
DAS280.110.220.066 to 0.15<0.001