MBL2 and rheumatoid arthritis: When the same exercise was performed after stratification by smoking status, the trend association observed between MBL-high genotype and RF-negative RA turned out to be confined to never smokers (OR 1.82, 95% CI 1.24 to 2.69) whereas no association was observed in ever smokers (OR 0.96, 95% CI 0.73 to 1.28).