Characteristics		Mean IL-6 level (pg/ml)	p-value
Sex	Female	15.08 ± 2.34	0.3
Sex	Male	16.21 ± 2.46	0.3
Smoking history (former smoker)	Yes	14.75 ± 1.86	0.006*
Smoking history (former smoker)	No	17.59 ± 2.16	0.006*
History of rheumatoid arthritis in parents	Yes	15.13 ± 2.66	0.67
History of rheumatoid arthritis in parents	No	15.50 ± 2.17	0.67
Disease activity	Remission	15.63 ± 2.12	0.02*
	Mild	19.77 ± 0.54
	Moderate	14.66 ± 2.18
	Severe	14.74 ± 2.14