Validation of repeated self-reported n-3 PUFA intake using serum phospholipid fatty acids as a biomarker in breast cancer patients during treatment

Table 6 Spearman correlation coefficients (ρ) and cross-classification for selected fatty acids, energy percent (E %) n = 49

Fatty acid		FFQ v. PFD				PFD v. Biomarker				FFQ v. Biomarker
				Cross-classification				Cross-classification				Cross-classification
	time‡	ρ	95% CI	ST	OT	ρ	95% CI	ST	OT	ρ	95% CI	ST	OT
n-3†	0	0.66*	0.47, 0.80	55	4	0.20	−0.08, 0.46	41	14	0.33*	0.06, 0.56	39	12
	6					0.39*	0.12, 0.60	45	12
	12	0.48*	0.23, 0.67	57	10	0.52*	0.28, 0.70	49	6	0.53*	0.29, 0.70	57	10
EPA	0	0.58*	0.35, 0.74	51	4	0.08	−0.21, 0.35	31	16	0.35*	0.08, 0.58	49	10
	6					0.27	−0.01, 0.51	37	16
	12	0.35*	0.08, 0.57	53	18	0.51*	0.26, 0.69	55	8	0.36*	0.09, 0.58	49	14
DHA	0	0.59*	0.36, 0.74	59	8	0.18	−0.11, 0.44	41	14	0.38*	0.11, 0.60	43	12
	6					0.39*	0.12, 0.60	53	14
	12	0.38*	0.11, 0.60	47	16	0.40*	0.13, 0.61	45	10	0.41*	0.14, 0.62	43	8

CI Confidence interval, PFD pre-coded food diary, FFQ food frequency questionnaire
Cross-classification, % classified in ST: same tertile, OT: opposite tertile, grossly misclassified
†n-3: sum n-3 (ALA (18:3n-3), EPA (20:5n-3), DPA (22:5n-3), DHA (22:6n-3)) for biomarker and total n-3 PUFAs for PFD/FFQ
‡time 0: around surgery (FFQ: presurgery, PFD; postsurgery, biomarker; presurgery), time 6: 6 months postsurgery, time 12: 12 months postsurgery
* p<0.05

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