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Table 5 Reproducibility of nutrient intakes of the SFFQ (n = 201)

From: Validity and reproducibility of a short food frequency questionnaire among patients with chronic kidney disease

 

Daily intakes

 

Pearson correlation coefficients

Cross-classification of nutrient distribution

 

SFFQ 1

SFFQ 2

SFFQ2-SFFQ1

SFFQ2 vs.SFFQ1

 

Mean (SD)

Means of differences (SD)

Unadjusted

Energy-adjusteda

ICC

% of subjects classified in same or adjacent quintiles

% of misclassified subjects

Energy (kcal)

1938.8 (808.9)

1745.6* (681.0)

−193.3 (801.1)

0.50

 

0.43

75

2

Protein (g)

77.9 (33.8)

70.8* (29.4)

−7.1 (32.7)

0.51

0.51

0.47

71

2

Carbohydrates (g)

221.7 (110.1)

199.5* (94.9)

−22.2 (118.9)

0.42

0.39

0.33

74

4

Fat (g)

67.1 (34.0)

61.0* (28.5)

−6.2 (30.7)

0.58

0.49

0.52

76

1

SFA (g)

25.3 (14.4)

23.5* (13.5)

−1.7 (13.8)

0.59

0.49

0.51

76

2

MUFA (g)

24.7 (13.2)

22.1* (10.6)

−2.6 (11.5)

0.59

0.53

0.54

75

1

PUFA (g)

10.2 (6.0)

9.0* (5.4)

−1.1 (5.4)

0.56

0.57

0.55

77

2

Cholesterol (mg)

278.7 (174.1)

248.0* (134.8)

−30.7 (157.3)

0.54

0.48

0.49

79

1

Sugars (g)

80.3 (51.7)

77.0* (63.7)

−3.3 (65.6)

0.54

0.48

0.36

79

2

Fibre (g)

20.5 (10.1)

18.3* (8.7)

−2.1 (10.9)

0.39

0.43

0.33

72

3

Alcohol (g)b

11.8 (23.2)

9.6 (15.5)

−2.2 (16.3)

0.90

 

0.66

97

0

Retinol (μg)

572.3 (505.2)

534.5* (750.5)

−37.8 (820.0)

0.48

0.46

0.18

81

4

Carotene (μg)

2467.3 (1742.6)

2308.5 (1618.7)

−158.8 (1474.7)

0.58

0.56

0.62

79

2

Vitamin B1 (mg)

1.0 (0.4)

1.0* (0.5)

−0.1 (0.5)

0.49

0.35

0.48

67

2

Vitamin B2 (mg)

1.6 (0.7)

1.4* (0.7)

−0.1 (0.7)

0.54

0.41

0.53

76

2

Vitamin B3 (mg)

17.6 (8.3)

16.2* (7.8)

−1.4 (8.2

0.46

0.44

0.48

72

4

Vitamin B5 (mg)

5.2 (2.1)

4.7* (2.2)

−0.5 (2.2)

0.49

0.37

0.49

73

3

Vitamin B6 (mg)

1.6 (0.7)

1.5* (0.6)

−0.1 (0.7)

0.47

0.41

0.45

73

4

Vitamin B9

307.4 (130.2)

282.2* (131.8)

−25.3 (138.5)

0.47

0.41

0.44

73

3

Vitamin B12 (μg)

7.2 (5.2)

6.3* (4.9)

−0.9 (6.3)

0.48

0.45

0.23

79

2

Vitamin C (mg)

107.0 (72.6)

105.6 (98.7)

−1.4 (100.7)

0.47

0.43

0.32

76

2

Vitamin D (μg)

2.1 (1.1)

2.0 (1.0)

−0.1 (1.2)

0.53

0.55

0.38

75

2

Vitamin E (mg)

12.2 (7.5)

10.7* (6.6)

−1.5 (6.5)

0.59

0.60

0.58

78

1

Calcium (mg)

962.2 (413.4)

908.0* (527.2)

−54.3 (456.2)

0.61

0.55

0.54

81

0

Iron (mg)

11.6 (5.6)

10.2* (4.5)

−1.3 (5.5)

0.46

0.37

0.42

71

1

Magnesium (mg)

353.2 (140.2)

325.8* (141.1)

−27.4 (146.4)

0.49

0.46

0.46

70

3

Zinc (mg)

9.8 (4.5)

8.8* (3.6)

−1.0 (4.4)

0.52

0.49

0.42

74

2

Phosphorus (mg)

1155.5 (471.3)

1058.8* (450.7)

−96.7 (473.2)

0.55

0.52

0.47

79

2

Manganese (mg)

11.8 (4.7)

10.9* (4.7)

−0.9 (4.9)

0.49

0.46

0.46

71

3

Potassium (mg)

3147.4 (1217.2)

2934.6* (1403.5)

−212.7 (1388.9)

0.50

0.41

0.44

74

1

Iodine (μg)

120.5 (58.0)

108.1* (47.6)

−12.4 (52.5)

0.58

0.57

0.51

79

2

Copper (mg)

2.5 (1.4)

2.3* (1.4)

−0.2 (1.5)

0.52

0.52

0.44

70

1

Sodium (mg)

2552.0 (1164.6)

2290.1* (1057.8)

−261.9 (1227.0)

0.42

0.32

0.39

67

3

Water (g)

2688.6 (1222.6)

2608.9 (1287.2)

−79.7 (1299.2)

0.53

0.44

0.46

70

2

  1. Means and cross-classification were computed on crudes variables. All variables were log transformed before computing Pearson correlation coefficients, to improve normality
  2. a Energy adjustment according to the residual method
  3. b Spearman correlation coefficients were performed because normality was not respected
  4. *Significantly different from the value of the SFFQ1, according to Wilcoxon signed rank tests
  5. The statistical tests provided p-values <0.05 for each Pearson correlation coefficient
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