Table 4

Three-way interaction for NAT2 genotype, CYP1A2 phenotype, and red meat preference

CYP1A2 Phenotypea
≤Median>Median
NAT2DonenessbNcORd (95% CI)NAT2DonenessNOR (95% CI)
Slow/intermediateRare/medium72.1121.0Slow/intermediateRare/medium93.1231.1 (0.7–1.8)
Slow/intermediateWell-done31.341.2 (0.7–2.3)Slow/intermediateWell-done28.401.0 (0.6–1.9)
RapidRare/medium43.611.0 (0.6–1.8)RapidRare/medium41.610.9 (0.5–1.5)
RapidWell-done19.271.0 (0.5–1.9)RapidWell-done21.83.3 (1.3–8.1)
P for interactione = 0.12
  • a As determined by the urinary ratio (17U + 17X):137X; median = 5.1.

  • b Rare/medium includes did not eat, rare, medium-rare, and medium. Well-done includes well-done and very well-done.

  • c Number of cases/number of controls.

  • d ORs (95% CIs) adjusted by unconditional logistic regression for age, sex, ethnicity, pack-years of cigarette smoking, number of cigarettes, cigars, and pipes smoked during the 2 weeks preceding the caffeine test, lifetime recreational physical activity, lifetime aspirin use, body mass index 5 years ago, years of schooling, and intakes of nonstarch polysaccharides from vegetables and calcium from foods and supplements.

  • e Based on the likelihood ratio test comparing the model with interactions with one containing only main effects for these three variables.