Table 3.

Treatment efficacy in preventing metachronous colorectal adenoma, stratified by biomarker level at baseline

		Biomarker level at baseline*
		Low	High	P†
PGE2
Placebo, events/total (%)		19/42 (45.2)	21/53 (39.6)
DFMO/sulindac, events/total (%)		12/53 (22.6)	3/44 (6.82)
RR (95% CI)		0.50 (0.28 – 0.91)	0.17 (0.05 – 0.54)	0.132
Spd:Spm
Placebo, events/total (%)		31/68 (45.6)	24/61 (39.3)
DFMO/sulindac, events/total (%)		5/64 (7.81)	12/72 (16.7)
RR (95% CI)		0.17 (0.07 – 0.41)	0.42 (0.23 – 0.77)	0.087
Putrescine
Placebo, events/total (%)		24/62 (38.7)	31/67 (46.3)
DFMO/sulindac, events/total (%)		7/70 (10.0)	10/66 (15.2)
RR (95% CI)		0.26 (0.12 – 0.56)	0.33 (0.18 – 0.61)	0.796

Abbreviations: DFMO, difluoromethylornithine; PGE2, prostaglandin E2; RR, relative risk; CI, confidence interval; Spd:Spm, spermidine-to-spermine ratio

^*Low versus high determined by the median biomarker level: low is below the median; high is above the median

^†P value for the likelihood ratio test of interaction between treatment group and low versus high biomarker level at baseline