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

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

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
  1. CI Confidence interval, PFD pre-coded food diary, FFQ food frequency questionnaire
  2. Cross-classification, % classified in ST: same tertile, OT: opposite tertile, grossly misclassified
  3. †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
  4. ‡time 0: around surgery (FFQ: presurgery, PFD; postsurgery, biomarker; presurgery), time 6: 6 months postsurgery, time 12: 12 months postsurgery
  5. * p<0.05