Table 4.

Median^a Cytokine Levels at Baseline, by Anti-CCP and RF Status,^b Among Participants in the Women's Health Initiative Rheumatoid Arthritis Study, 2009–2011

Cytokine	Anti-CCP and RF Status and Baseline Cytokine Level, pg/mL
	Anti-CCP+ (n = 770)c			Anti-CCP− (n = 2,214)d			P Value (Anti-CCP+ vs. Anti-CCP−)
	RF− (n = 157)	RF+ (n = 613)	P Value	RF− (n = 1,912)	RF+ (n = 302)	P Value	RF+	RF−
IL-1b	1.6	2.4	<0.0001	1.5	1.8	<0.0001	<0.0001	0.661
IL-2	3.3	12.6	<0.0001	3.2	5.3	<0.0001	<0.0001	0.587
IL-4	1.6	2.3	<0.0001	1.6	1.8	0.001	<0.0001	0.916
IL-5	3.0	4.1	<0.0001	3.0	3.3	<0.0001	<0.0001	0.641
IL-6	6.3	15.2	<0.0001	6.1	7.5	<0.0001	<0.0001	0.092
IL-7	6.9	8.5	<0.0001	6.9	7.6	<0.0001	0.001	0.908
IL-8	8.9	9.8	0.001	8.6	9.3	0.001	0.303	0.247
IL-10	2.5	3.2	<0.0001	2.4	2.7	<0.0001	<0.0001	0.292
IL-12	12.0	22.9	<0.0001	12.6	16.0	<0.0001	<0.0001	0.756
IL-13	2.4	4.3	<0.0001	2.4	3.0	<0.0001	<0.0001	0.796
Granulocyte-macrophage colony-stimulating factor	144.0	170.2	0.001	147.1	141.9	0.758	0.001	0.800
Monocyte chemotactic protein 1	15.3	20.9	<0.0001	14.5	16.2	<0.0001	<0.0001	0.265
Macrophage inflammatory protein 1β	45.4	45.9	0.877	41.9	46.5	0.0003	0.530	0.043
Tumor necrosis factor α	21.7	37.7	<0.0001	21.6	25.1	<0.0001	<0.0001	0.605
Interferon γ	40.8	74.8	<0.0001	41.1	50.6	<0.0001	<0.0001	0.749
IL-17	0.8	4.2	<0.0001	0.4	2.3	<0.0001	0.007	0.820
White blood cell count (× 109 cells/L)	5.5	6.2	<0.0001	5.8	5.7	0.088	<0.0001	0.041

Abbreviations: anti-CCP, anti-cyclic citrullinated peptide; DMARDs, disease-modifying antirheumatic drugs [excluding prednisone]; IL, interleukin; RF, rheumatoid factor.

^a Wilcoxon test of median values.

^b +, positive; –, negative.

^c Information on RF status was missing for 2 women; information on cytokine levels was missing for 2 women.

^d Information on RF status was missing for 2 women; information on cytokine levels was missing for 3 women.