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Applying inappropriate cutoffs leads to misinterpretation of folate status in the US population.

Authors :
Pfeiffer CM
Sternberg MR
Hamner HC
Crider KS
Lacher DA
Rogers LM
Bailey RL
Yetley EA
Source :
The American journal of clinical nutrition [Am J Clin Nutr] 2016 Dec; Vol. 104 (6), pp. 1607-1615. Date of Electronic Publication: 2016 Sep 28.
Publication Year :
2016

Abstract

Background: Folate cutoffs for risk of deficiency compared with possible deficiency were originally derived differently (experimental compared with epidemiologic data), and their interpretations are different. The matching of cutoffs derived from one assay with population-based data derived from another assay requires caution.<br />Objective: We assessed the extent of folate-status misinterpretation with the use of inappropriate cutoffs.<br />Design: In the cross-sectional NHANES, serum and red blood cell (RBC) folate were first measured with the use of a radioprotein-binding assay (RPBA) (1988-2006) and, afterwards, with the use of a microbiologic assay (2007-2010). We compared prevalence estimates for assay-matched cutoffs (e.g., with the use of an RPBA cutoff with RPBA data) and assay-mismatched cutoffs (e.g., with the use of microbiologic assay cutoff with RPBA data) for risk of deficiency on the basis of megaloblastic anemia as a hematologic indicator in persons ≥4 y of age (e.g., serum folate concentration <7 nmol/L and RBC folate concentration <305 nmol/L derived with the use of a microbiologic assay), possible deficiency on the basis of rising homocysteine as a metabolic indicator in persons ≥4 y of age (e.g., serum folate concentration <10 nmol/L and RBC folate concentration <340 nmol/L derived with the use of an RPBA), and insufficiency on the basis of elevated risk of neural tube defects in women 12-49 y old (e.g., RBC folate concentration <906 nmol/L derived with the use of a microbiologic assay).<br />Results: Pre-folic acid fortification (1988-1994), risks of deficiency for assay-matched compared with assay-mismatched cutoffs were 5.6% compared with 16% (serum folate), respectively, and 7.4% compared with 28% (RBC folate), respectively; risks declined postfortification (1999-2006) to <1% compared with <1% (serum folate), respectively, and to <1% compared with 2.5% (RBC folate), respectively. Prefortification (1988-1994), risks of possible deficiency for assay-matched compared with assay-mismatched cutoffs were 35% compared with 56% (serum folate), respectively, and 37% compared with 84% (RBC folate), respectively; risks declined postfortification (1999-2006) to 1.9% compared with 7.0% (serum folate), respectively, and to 4.8% compared with 53% (RBC folate), respectively. Postfortification (2007-2010), risks of insufficiency were 3% (assay matched) compared with 39% (assay mismatched), respectively.<br />Conclusions: The application of assay-mismatched cutoffs leads to a misinterpretation of folate status. This confusion likely applies to clinical assays because no comparability data are available, to our knowledge.<br /> (© 2016 American Society for Nutrition.)

Details

Language :
English
ISSN :
1938-3207
Volume :
104
Issue :
6
Database :
MEDLINE
Journal :
The American journal of clinical nutrition
Publication Type :
Academic Journal
Accession number :
27680995
Full Text :
https://doi.org/10.3945/ajcn.116.138529