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Table 6 Mean intakes estimated from the 2nd DHQ across quintiles of intakes estimated from the 1st DHQ (n = 58)

From: Validity and reproducibility of folate and vitamin B12 intakes estimated from a self-administered diet history questionnaire in Japanese pregnant women

  1st DHQ Agreement (% classified into the same or adjacent quintile)1 Discordance (% classified into the opposite quintile)1 Linear trend2
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  1st quintile 2nd quintile 3rd quintile 4th quintile 5th quintile    
  Mean ± SD Mean ± SD Mean ± SD Mean ± SD Mean ± SD    
2nd DHQ         
   Energy [kcal/day] 1452 ± 498 1786 ± 292 1591 ± 227 1908 ± 300 2120 ± 323 70.7 1.7 < 0.001
   Folate [μg/day]3 185 ± 44 241 ± 37 243 ± 60 288 ± 63 447 ± 126 81.1 0 < 0.001
   Vitamin B12 [μg/day]3 4.44 ± 2.32 5.03 ± 2.41 5.27 ± 1.51 6.16 ± 1.78 8.77 ± 4.36 77.6 1.7 < 0.001
  1. DHQ: self-administered diet history questionnaire
  2. 1Agreement and discordance in quintile ranking was assessed as the percentage classification for the pregnant women based on the two-time DHQ in the same, adjacent, and opposite quintiles
  3. 2Linear regression analyses were performed to test for significant linear trends between estimated intakes from the two-time DHQ
  4. 3Linear regression analyses were conducted after log-transformation of the variables