Mannan Binding Lectin (MBL) genotypes coding for high MBL serum levels are associated with rheumatoid factor negative rheumatoid arthritis in never smokers

Table 2 Rheumatoid arthritis risk associated with MBL-high genotype in the whole EIRA study group and stratified for serology and smoking status

	Whole group		Never smokers	Ever smokers
	Number of cases/controls	OR (95% CI) ^a	OR (95% CI) ^a	OR (95% CI) ^a
Whole group	1,666/920	1.03 (0.87-1.21)	1.39 (1.04-1.85)	0.83 (0.67-1.04)
Stratification by serological status
Seronegative
RF-	476/920	1.20 (0.96-1.51)	1.82 (1.24-2.69)	0.96 (0.73-1.28)
ACPA-	585/920	1.03 (0.83-1.27)	1.42 (0.98-2.05)	0.77 (0.58-1.04)
RF-/ACPA-	361/920	1.14 (0.89-1.47)	1.67 (1.10-2.55)	0.80 (0.56-1.13)
RF-/ACPA+^b	105/920	1.54 (0.99-2.38)	3.07 (1.37-6.89)	1.06 (0.57-1.99)
Seropositive
RF+	925/920	1.00 (0.83-1.20)	1.26 (0.89-1.78)	0.86 (0.68-1.10)
ACPA+	916/920	1.08 (0.89-1.30)	1.55 (1.08-2.23)	0.88 (0.69-1.13)
RF+/ACPA-^c	172/920	0.83 (0.59-1.17)	0.96 (0.53-1.74)	0.74 (0.47-1.17)
RF+/ACPA+	744/920	1.06 (0.87-1.29)	1.42 (0.97-2.10)	0.90 (0.70-1.16)

^aRisk was calculated as odds ratios (ORs) with 95% confidence intervals (CIs) adjusted for age, sex, and geographic location by using logistic regression. ^bIn the ACPA+ group, 20% of never smokers and 10% of smokers were RF-: OR 2.07 (1.36 to 3.14), P = 0.0005. ^cIn the RF+ group, 24% of never smokers and 17% of smokers were ACPA-: OR 1.58 (1.11 to 2.25), P = 0.01. ACPA, anti-citrullinated protein antibody; EIRA, Epidemiological Investigation of Rheumatoid Arthritis; MBL, mannan-binding lectin; RF, rheumatoid factor.

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