title: Population red blood cell folate concentrations for prevention of neural tube defects: Bayesian model.
abstract: OBJECTIVE
  To determine an optimal population red blood cell (RBC) folate concentration for the prevention of neural tube birth defects.
  
  
  METHODS
  Bayesian model.
  
  
  METHODS
  Data from two population based studies in China.
  
  
  METHODS
  247,831 participants in a prospective community intervention project in China (1993-95) to prevent neural tube defects with 400 μg/day folic acid supplementation and 1194 participants in a population based randomized trial (2003-05) to evaluate the effect of folic acid supplementation on blood folate concentration among Chinese women of reproductive age.
  
  
  METHODS
  Folic acid supplementation (400 μg/day).
  
  
  METHODS
  Estimated RBC folate concentration at time of neural tube closure (day 28 of gestation) and risk of neural tube defects.
  
  
  RESULTS
  Risk of neural tube defects was high at the lowest estimated RBC folate concentrations (for example, 25.4 (95% uncertainty interval 20.8 to 31.2) neural tube defects per 10,000 births at 500 nmol/L) and decreased as estimated RBC folate concentration increased. Risk of neural tube defects was substantially attenuated at estimated RBC folate concentrations above about 1000 nmol/L (for example, 6 neural tube defects per 10,000 births at 1180 (1050 to 1340) nmol/L). The modeled dose-response relation was consistent with the existing literature. In addition, neural tube defect risk estimates developed using the proposed model and population level RBC information were consistent with the prevalence of neural tube defects in the US population before and after food fortification with folic acid.
  
  
  CONCLUSIONS
  A threshold for "optimal" population RBC folate concentration for the prevention of neural tube defects could be defined (for example, approximately 1000 nmol/L). Population based RBC folate concentrations, as a biomarker for risk of neural tube defects, can be used to facilitate evaluation of prevention programs as well as to identify subpopulations at elevated risk for a neural tube defect affected pregnancy due to folate insufficiency.
authors: National Center on Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA kcrider@cdc.gov.
authors: Krista S
authors: KS
authors: Crider
authors: National Center on Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA.
authors: Owen
authors: O
authors: Devine
authors: Peking University Health Science Center, Peking University, Beijing, China US Centers for Disease Control and Prevention, US Embassy, Beijing, China.
authors: Ling
authors: L
authors: Hao
authors: National Center on Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA.
authors: Nicole F
authors: NF
authors: Dowling
authors: Peking University Third Hospital, Beijing, China.
authors: Song
authors: S
authors: Li
authors: School of Medicine, Trinity College, Dublin, Ireland.
authors: Anne M
authors: AM
authors: Molloy
authors: Peking University Health Science Center, Peking University, Beijing, China.
authors: Zhu
authors: Z
authors: Li
authors: Peking University Health Science Center, Peking University, Beijing, China Division of Risk Assessment, China National Center for Food Safety Risk Assessment, Beijing, China.
authors: Jianghui
authors: J
authors: Zhu
authors: National Center on Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA.
authors: Robert J
authors: RJ
authors: Berry
mesh_terms: D001499:Bayes Theorem; D004912:Erythrocytes / Q000737:chemistry*; D005260:Female; D005492:Folic Acid / Q000008:administration & dosage / Q000378:metabolism*; D005494:Folic Acid Deficiency / Q000178:diet therapy / Q000235:genetics / Q000517:prevention & control; D005838:Genotype; D006397:Hematinics / Q000008:administration & dosage; D006801:Humans; D042965:Methylenetetrahydrofolate Reductase (NADPH2) / Q000235:genetics; D009436:Neural Tube Defects / Q000178:diet therapy / Q000235:genetics / Q000517:prevention & control*; D011247:Pregnancy; D011295:Prenatal Care / Q000379:methods; D011446:Prospective Studies; D016032:Randomized Controlled Trials as Topic
chemical_list: D006397:Hematinics; D005492:Folic Acid; C573423:MTHFR protein, human; D042965:Methylenetetrahydrofolate Reductase (NADPH2)