Table 2.

Odds ratios and 95% CIs for MS in each stratum of IM and HLA genotype. In the top half of the table, odds ratios are derived from meta-analysis of all studies. In the bottom half, estimates of additive and multiplicative interaction are shown with their standard errors. These estimates are derived from only those studies with individual-level data (i.e. number of participants in each stratum) available.

	HLA–	HLA+
IM– (OR; 95% CI)	1 (reference)	2.75 (2.07–3.64)
IM+ (OR; 95% CI)	1.22 (0.33–4.48)	5.11 (2.00–13.03)
	Estimate	SE (p)
AP	0.29	0.15 (0.053)
RERI	0.48	0.97 (0.624)
Log(synergy index)	0.48	0.29 (0.100)
Multiplicative interaction	1.71	0.93 (0.443)

OR: odds ratio; CI: confidence interval; AP: attributable proportion due to interaction; RERI: relative excess risk due to interaction.