CXCL8 and rheumatoid arthritis: For RA versus controls IL8 had the highest OR; RA with PF OR (95%CI) 2.29 (1.55, 3.37), p < 0.001 and without PF OR (95% CI) 2.53 (1.74, 3.69), p < 0.001, adjusted for sex, age and smoking (Table 2).