Table 4 Association of ex vivo IL1β and IL1Ra production and baseline disease characteristics with progression of joint damage*.

Baseline variables	Univariate analysis			Multivariate analysis†
	Standardised coefficient	R2†	p Value	Standardised coefficient	p Value
Age	−0.163	0.026	0.179	–	–
Gender	−0.187	0.035	0.121	–	–
IL1β	−0.046	0.002	0.710	−0.05	0.715
IL1Ra	0.209	0.044	0.082	0.274	0.036
Treatment group‡	−0.382	0.146	0.001	−0.399	0.002
Duration of complaints	0.055	0.003	0.651	–	–
CRP	0.059	0.003	0.648	0.151	0.276
Anti‐CCP	0.154	0.024	0.229	–	–
Rheumatoid factor	0.125	0.016	0.304	–	–
Ritchie articular index	−0.078	0.006	0.520	–	–
Total swollen joint count	−0.142	0.02	0.242	−0.042	0.747
HAQ	0.165	0.027	0.174	0.087	0.517
VAS morning stiffness	0.032	0.001	0.794	−0.101	0.459
SHS	0.327	0.107	0.007	0.151	0.118

CCP, cyclic‐citrullinated peptide; CRP, C reactive protein; HAQ, health assessment questionnaire; IL1β, interleukin 1 beta; IL1Ra, interleukin 1 receptor antagonist; SHS, Sharp–van der Heijde Score; VAS, visual analogue scale–baseline variables not selected for multivariate analysis after backward selection procedure.

*Univariate and multivariate linear regression; regression coefficients, R² and p values.

†R² = explained variance; †multivariate linear regression analysis including the variables selected by backward selection procedure and IL1β and IL1Ra.

‡Treatment groups are: sequential monotherapy, step‐up combination therapy, initial combination therapy with prednisone and initial combination therapy with infliximab.