Arachidonic acid and colorectal adenoma risk: a Mendelian randomization study

Figures & data

Table 1 Baseline characteristics for patients based on case status

	Cases,a n=909	Controls,b n=855	P-value
Age, years (mean ± SD)	58.9±7.2	56.6±7.1	<0.0001
Sex, % female	25.2	26.0	0.62
Race, %
White	91.9	92.2	0.88
African-American	6.5	6.1
Other	1.7	1.8
Alcohol use, %
Current	47.4	19.8	0.001
Former	27.7	23.4
Never	24.6	56.5
Unknown	0.2	0.4
Current smokers, %	77.0	67.0	<0.0001
Facility site, % Vanderbilt	63.3	64.4	0.64
BMI (mean ± SD), kg/m^2	28.4±5.15	28.1±5.28	0.24
Screening reason, %
Yearly screening	58.9	58.3	0.60
Family history	10.8	12.6
Diagnostic/bleeding/follow-up	21.9	20.8
Other	8.5	8.3
Unknown	0	0
NSAIDS, %
Never	42.7	38.3	0.05
Former	6.9	7.6
Current	49.4	53.9
Unknown	1.0	0.2

Notes:

a Case is a patient with a pathologically confirmed adenoma on colonoscopy.

b Control has no adenoma on colonoscopy.

Abbreviation: BMI, body mass index.

Table 2 rs174537 allele and erythrocyte ARA concentration

Alleles	ARA concentrationa (%)	P-value
GG	16.71±3.68	<0.0001b
GT	15.95±3.77
TT	15.25±3.19

Notes:

a ARA concentrations are displayed as the mean ± SD. The concentration is the percentage of erythrocyte phospholipid membrane that is made of up ARA.

b ANOVA test.

Abbreviation: ARA, arachidonic acid.

Table 3 Baseline characteristics stratified by allele

	GG n=804	GT n=774	TT n=186	P-value
Age, years (mean ± SD)	57.5±7.02	57.9±7.46	58.5±7.16	0.221
Sex, % female	27.1	24.4	23.7	0.386
Race, %
White	86.8	96.4	96.2	<0.0001*
African-American	11.2	2.6	0.5
Other	2.0	1.03	3.2
Alcohol use, %
Current	20.9	23.9	21.5	0.525
Former	27.5	24.0	24.2
Never	51.2	51.9	53.8
Unknown	0.4	0.1	0.5
BMI (mean ± SD), kg/m^2	28.1±5.05	28.41±5.30	28.5±5.58	0.40
NSAIDS, %
Never	42.5	39.0	38.2	0.623
Former	7.7	6.9	7.0
Current	49.1	53.6	53.8
Unknown	0.6	0.5	1.1

Note:

* Indicates a statistically significant P-value.

Abbreviation: BMI, body mass index.

Table 4 OR for colorectal adenoma by allele

Alleles	OR (95% CI)	P-value
GG	1.07 (0.97–1.02)	0.41a
GT	1.24 (0.9–1.71)
TT	1.00 (reference)

Notes:

a A two-stage MR analysis was performed to determine the relationship between the rs174537 allele and colorectal adenomas.

Abbreviation: MR, Mendelian randomization.