Trial reportThe American journal of clinical nutrition2020
Population RBC folate concentrations can be accurately estimated from measured whole blood folate, measured hemoglobin, and predicted serum folate-cross-sectional data from the NHANES 1988-2010.
Trial report in The American journal of clinical nutrition, 2020. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 2 papers.
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Who cites it
2 citing papers in PubMed, 2 citations in OpenAlex.
- Folate and Vitamin B12 Status among Non-Pregnant, Non-Lactating Women of Reproductive Age and Predicted Risk for Neural Tube Defects, Morogoro Region, Tanzania.Maternal and child health journal · 2025Article
- Concordance between Hemoglobin and Hematocrit among Children and Pregnant Persons in National Health and Nutrition Examination Survey Data, 1999-2020.The Journal of nutrition · 2025Article
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Authors and funding
4 authors at 2 institutions in 1 country.
Funding
Abstract
backgroundRBC folate (RBF) is an indicator of folate status and risk of neural-tube defects. It is calculated from whole blood folate (WBF), serum folate (SFOL), and hematocrit (Hct). SFOL and/or Hct are sometimes unavailable; hemoglobin (Hb) is generally available in surveys.
objectivesWe assessed the ability of different RBF approximations to generate population data in women aged 12-49 y.
methodsUsing SFOL, RBF, Hct, Hb, and mean corpuscular Hb content (MCHC) from prefortification (1988-1994) and postfortification (1999-2006, 2007-2010) NHANES we applied 6 approaches: #1) assume SFOL = 0; #2) impute SFOL (population median); #3) impute Hct (population median); #4) estimate Hct (Hb/MCHC); #5) assume SFOL = 0 and estimate Hct; and #6) predict SFOL (from WBF) and estimate Hct. For each approach, we calculated the paired percentage difference to the "true" RBF and estimated various statistics.
resultsFor 2007-2010 (unweighted data), the median relative difference from "true" RBF was lowest for approaches #2 (-0.74%), #4 (-0.96%), and #6 (-1.15%), intermediate for #3 (-3.36%), and highest for #5 (4.96%) and #1 (5.78%). The 95% agreement limits were smallest for approach #1 (2.33%, 13.0%) and largest for #3 (-20.8%, 11.3%). Approach #2 showed concentration-dependence (negative compared with positive differences at low compared with high RBF). Using weighted data, we found similar patterns across approaches for mean relative differences by demographic subgroup for all 3 time periods.
conclusionsWe obtained the best agreement between estimated and "true" RBF when we predicted SFOL using a regression equation obtained from a subset of samples (approach #6). Alternatively, the consistent overestimation of RBF when assuming SFOL = 0 (∼6%) could be addressed by adjusting the data (approach #5). Similar observations for pre- and postfortification periods suggest applicability to low and high folate status situations, but should be confirmed elsewhere. To estimate RBF, at least WBF and Hb are needed.
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