Table 5

Interaction betweenUCHL1 S18Y polymorphism and caffeine intake affecting sporadic Parkinson’s disease in a Japanese population
Caffeine intake
≥ 161.7 mg/4184 kJ < 161.7 mg/4184 kJ
Genotype No. cases/controls Adjusted OR (95 % CI)* No. cases/controls Adjusted OR (95 % CI)*
CC + CA 58/140 1.00 101/139 1.82 (1.21 − 2.75)
AA 28/38 1.87 (1.03 − 3.36) 42/40 2.66 (1.55 − 4.59)
P for multiplicative interaction = 0.55
Measures of additive interaction
 Relative excess risk due to interaction (RERI) = −0.02 (95 % CI: -1.63 − 1.59)
 Attributable proportion due to interaction (AP) = −0.01 (95 % CI: -0.61 − 0.60)
 Synergy index (S) = 0.99 (95 % CI: 0.38 − 2.58)

*Adjusted for sex, age, region of residence, and smoking.

Statistically significant when the 95 % CI of RERI > 0, the 95 % CI of AP > 0, or the 95 % CI of S > 1, indicating additive interaction.

Miyake et al.

Miyake et al. BMC Neurology 2012 12:62   doi:10.1186/1471-2377-12-62

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