Fig 1.
Study food frequency questionnaire focusing on food items containing marine n-3 polyunsaturated fatty acids (English version).
The study subjects responded to the question “During a typical month, how often do you eat these food items?” using one of six response alternatives for each of the ten food item categories.
Table 1.
Patient characteristics at baseline eight weeks after renal transplantation according to plasma phospholipid marine n-3 fatty acid tertiles.
Fig 2.
Scatterplots of standardized plasma PL marine n-3FA levels and standardized FFQ based marine n-3FA consumption estimates with regression line at eight weeks post-transplant (n = 132).
Fig 3.
Bland-Altman plot assessing degree of agreement between standardized plasma PL marine n-3FA levels and standardized FFQ based marine n-3FA consumption estimates at baseline eight weeks post-transplant.
We used standardization of data obtained by the study FFQ and reference biomarker, hence the mean value was set at 0. The upper and lower limits of agreement were set at 2 standard deviations from the mean. The Bland Altman plot includes all patients enrolled in the ORENTRA trial (n = 132) at the baseline time-point.
Fig 4.
Scatterplots of standardized plasma PL marine n-3FA levels and standardized FFQ based marine n-3FA consumption estimates with regression line at one year post-transplant for patients belonging to the control group of the ORENTRA trial (n = 64).
Fig 5.
Bland-Altman plot assessing degree of agreement between standardized plasma PL marine n-3FA levels and standardized FFQ based marine n-3FA consumption estimates at one year post-transplant.
We used standardization of data obtained by the study FFQ and reference biomarker, hence the mean value was set at 0. The upper and lower limits of agreement were set at 2 standard deviations from the mean. The Bland Altman plot includes only patients belonging to the control group of the ORENTRA trial (n = 64) at the end of study time-point.
Table 2.
Summary of selected food frequency questionnaire validation studies published during the last six years, focusing on fish and/or marine fatty acid consumption, using circulating phospholipids or erytrocytes as the reference biomarker.