Table 4.

Urinary levels of [pyridine-D4]hydroxy acid:total [pyridine-D4]NNAL ratio by PEITC treatment stratified by GSTM1 and GSTT1 genotypes, The PEITC Intervention Study 2008–2013

Geometric means of [pyridine-D4]hydroxy acid:total [pyridine-D4]NNAL ratio
GST genotypesNPlaceboPEITC% Difference (95% CI)P valueaP for interactionb
GSTM1
 Null370.4230.397−6.2 (−16.5–5.3)0.2840.694
 Present450.4830.441−8.8 (−15.9–−1.1)0.031
GSTT1
 Null190.3870.344−11.1 (−19.7–−1.6)0.0370.574
 Present630.4780.446−6.7 (−14.2–1.5)0.111
GSTM1 & GSTT1
 Both null120.3730.314−15.6 (−26.7–−2.9)0.039
 Only one gene present320.4450.431−3.1 (−14.6–9.9)0.6230.436
 Both genes present380.4960.450−9.4 (−17.4–−0.6)0.045
  • aTwo-sided P values were derived from the mixed models to test PEITC treatment effect within specific GST genotype group.

  • bTwo-sided P values were derived from the mixed models to test the modifying effect of genotype on PEITC's effect on the [pyridine-D4]hydroxy acid:total [pyridine-D4]NNAL ratio.