Table 2 Risk of having progression of joint space narrowing (JSN) in relation to quartiles of ex vivo production of interleukin (IL)1β, tumour necrosis factor (TNF)α, IL1 receptor antagonist (IL1Ra) and IL10 production upon lipopolysaccharide stimulation in whole blood assays

Cytokine quartiles (pg/ml)*	Patients with progression, no.	Patients without progression, no.	Adjusted RR (95% CI)†	p Value
IL1β:
547–2045	7	14	1	–
2046–3073	5	16	0.8 (0.2 to 1.8)	0.640
3074–4209	9	13	1.3 (0.5 to 2.2)	0.495
4210–11 459	8	13	1.3 (0.5 to 2.0)	0.604
TNFα:
2924–5207	2	19	1	–
5208–7087	7	14	4.5 (0.8 to 9.1)	0.074
7088–10 045	10	12	5.5 (1.2 to 9.5)	0.031
10 046–21 405	10	11	6.1 (1.4 to 9.8)	0.024
IL1Ra:
12 742–19 191	4	17	1	–
19 192–23 584	8	13	2.1 (0.8 to 3.7)	0.124
23 585–28 317	9	13	2.3 (0.8 to 4.0)	0.117
28 318–57 311	8	13	2.1 (0.7 to 3.9)	0.151
IL10:
182–520	3	18	1	–
521–720	8	13	2.7 (0.8 to 5.3)	0.089
721–936	6	16	2.0 (0.5 to 4.7)	0.284
937–2117	12	9	4.3 (1.7 to 6.2)	0.006

*Quartiles of cytokine production, based on the distribution of IL1β, TNFα, IL1Ra) and IL10 production in the whole population. †The risk ratios (RRs) are adjusted for age, sex and body mass index. The 95% CIs are based on robust standard errors to take into account the intrafamily effect.