Polymorphisms in cytochrome P450 2C19 enzyme and cessation of leflunomide in patients with rheumatoid arthritis

Table 3 Association of phenotypes and genotypes with cessation due to side effects

SNP	Phenotype/Genotype	Proportion ceased due to side effects (%)	Hazard Ratio (95% Confidence Interval), *P-value
CYP2C19 (CYP2C192* (rs4244285), CYP2C1917* (rs12248560))	Poor/Intermediate metabolizers	8/15 (53.3%)	0.432 (0.237 to 0.790), P = 0.006†
	Extensive metabolizers	18/39 (46.2%)
	Ultra-rapid metabolizers	5/21 (23.8%)
ABCG2 421C>A (rs2231142)	AC	6/14 (42.9%)	1.297 (0.527 to 3.194), P = 0.572
	CC	27/64 (42.2%)
CYP1A21F* (rs762551)	AA	16/38 (42.1%)	1.021 (0.508 to 2.050), P = 0.954
	AC +CC	17/40 (42.5%)
DHODH 19C>A (rs3213422)	AA	9/20 (45%)	1.002 (0.610 to 1.648), P = 0.993†
	AC	16/39 (41.0%)
	CC	8/19 (42.1%)

All genotypes are in Hardy-Weinberg equilibrium. *after adjustment for dose, continuing triple therapy and positive rheumatoid factor. † Hazard Ratio and P-value represent a linear test for trend. The Hazard Ratio refers to the hazard associated with each incremental change in phenotype.

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