Table 6.

Three way interaction on the additive scale between HLA-DRB1*15, absence of HLA-A*02 and smoking

Study	AP3	RERI3	SI3
EIMS	0.4 (0.1–0.6)	4.4 (0.3–8.4)	1.7 (1.1–2.8)
GEMS	−0.02 (−0.3 to 0.3)	−0.2 (−3.1 to 2.6)	1.0 (0.7–1.3)
Danish study	0.09 (0.2–0.3)	1.6 (−3.4 to 6.5)	1.1 (0.8–1.5)
Norwegian study	0.2 (−0.3 to 0.7)	4.1 (−7.9 to 16.1)	1.3 (0.6–2.8)
Nordic studies combined	0.2 (0.002–0.3)	1.9 (−0.16 to 3.92)	1.2 (1.0–1.4)

Total attributable proportion due to interaction, relative excess risk and synergy index due to interaction, with 95% CI