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Folic Acid Supplementation for the Prevention of Neural Tube Defects: An Updated Evidence Report and Systematic Review for the US Preventive Services Task Force.

Abstract

Importance

Neural tube defects are among the most common congenital anomalies in the United States. Periconceptional folic acid supplementation is a primary care-relevant preventive intervention.

Objective

To review the evidence on folic acid supplementation for preventing neural tube defects to inform the US Preventive Services Task Force for an updated Recommendation Statement.

Data Sources

MEDLINE, Cochrane Library, EMBASE, and trial registries through January 28, 2016, with ongoing surveillance through November 11, 2016; references; experts.

Study Selection

English-language studies of folic acid supplementation in women. Excluded were poor-quality studies; studies of prepubertal girls, men, women without the potential for childbearing, and neural tube defect recurrence; and studies conducted in developing countries.

Data Extraction and Synthesis

Two investigators independently reviewed abstracts, full-text articles, and risk of bias of included studies. One investigator extracted data and a second checked accuracy. Because of heterogeneity, data were not pooled.

Main Outcomes and Measures

Neural tube defects, harms of treatment (twinning, respiratory outcomes).

Results

A total of 24 studies (N > 58 860) were included. In 1 randomized clinical trial from Hungary initiated in 1984, incidence of neural tube defects for folic acid supplementation compared with trace element supplementation was 0% vs 0.25% (Peto odds ratio [OR], 0.13 [95% CI, 0.03-0.65]; n = 4862). Odds ratios from cohort studies recruiting participants between 1984 and 1996 demonstrated beneficial associations and ranged from 0.11 to 0.27 (n = 19 982). Three of 4 case-control studies with data from 1976 through 1998 reported ORs ranging from 0.6 to 0.7 (n > 7121). Evidence of benefit led to food fortification in the United States beginning in 1998, after which no new prospective studies have been conducted. More recent case-control studies drawing from data collected after 1998 have not demonstrated a protective association consistently with folic acid supplementation, with ORs ranging from 0.93 to 1.4 and confidence intervals spanning the null (n > 13 990). Regarding harms, 1 trial (OR, 1.40 [95% CI, 0.89-2.21]; n = 4767) and 1 cohort study (OR, 1.04 [95% CI, 0.91-1.18]; n = 2620) found no statistically significant increased risk of twinning. Three systematic reviews found no consistent evidence of increased risk of asthma (OR, 1.06 [95% CI, 0.99-1.14]; n = 14 438), wheezing, or allergy.

Conclusions and Relevance

In studies conducted before the initiation of food fortification in the United States in 1998, folic acid supplementation provided protection against neural tube defects. Newer postfortification studies have not demonstrated a protective association but have the potential for misclassification and recall bias, which can attenuate the measured association of folic acid supplementation with neural tube defects.

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  • Publisher Full Text
  • Authors+Show Affiliations

    ,

    RTI International, Evidence-based Practice Center, University of North Carolina at Chapel Hill2RTI International, Research Triangle Park, North Carolina.

    ,

    RTI International, Evidence-based Practice Center, University of North Carolina at Chapel Hill.

    ,

    RTI International, Research Triangle Park, North Carolina.

    ,

    RTI International, Evidence-based Practice Center, University of North Carolina at Chapel Hill3Cecil G. Sheps Center for Health Services Research, University of North Carolina at Chapel Hill.

    ,

    RTI International, Evidence-based Practice Center, University of North Carolina at Chapel Hill3Cecil G. Sheps Center for Health Services Research, University of North Carolina at Chapel Hill.

    Department of Obstetrics and Gynecology, University of North Carolina at Chapel Hill.

    Source

    JAMA 317:2 2017 01 10 pg 190-203

    MeSH

    Adolescent
    Adult
    Advisory Committees
    Dietary Supplements
    Female
    Folic Acid
    Humans
    Neural Tube Defects
    Pregnancy
    Primary Prevention
    United States
    Vitamin B Complex
    Young Adult

    Pub Type(s)

    Journal Article
    Research Support, N.I.H., Extramural
    Research Support, Non-U.S. Gov't
    Review
    Systematic Review

    Language

    eng

    PubMed ID

    28097361

    Citation

    Viswanathan, Meera, et al. "Folic Acid Supplementation for the Prevention of Neural Tube Defects: an Updated Evidence Report and Systematic Review for the US Preventive Services Task Force." JAMA, vol. 317, no. 2, 2017, pp. 190-203.
    Viswanathan M, Treiman KA, Kish-Doto J, et al. Folic Acid Supplementation for the Prevention of Neural Tube Defects: An Updated Evidence Report and Systematic Review for the US Preventive Services Task Force. JAMA. 2017;317(2):190-203.
    Viswanathan, M., Treiman, K. A., Kish-Doto, J., Middleton, J. C., Coker-Schwimmer, E. J., & Nicholson, W. K. (2017). Folic Acid Supplementation for the Prevention of Neural Tube Defects: An Updated Evidence Report and Systematic Review for the US Preventive Services Task Force. JAMA, 317(2), pp. 190-203. doi:10.1001/jama.2016.19193.
    Viswanathan M, et al. Folic Acid Supplementation for the Prevention of Neural Tube Defects: an Updated Evidence Report and Systematic Review for the US Preventive Services Task Force. JAMA. 2017 01 10;317(2):190-203. PubMed PMID: 28097361.
    * Article titles in AMA citation format should be in sentence-case
    TY - JOUR T1 - Folic Acid Supplementation for the Prevention of Neural Tube Defects: An Updated Evidence Report and Systematic Review for the US Preventive Services Task Force. AU - Viswanathan,Meera, AU - Treiman,Katherine A, AU - Kish-Doto,Julia, AU - Middleton,Jennifer C, AU - Coker-Schwimmer,Emmanuel J L, AU - Nicholson,Wanda K, PY - 2017/1/19/entrez PY - 2017/1/18/pubmed PY - 2017/2/10/medline SP - 190 EP - 203 JF - JAMA JO - JAMA VL - 317 IS - 2 N2 - Importance: Neural tube defects are among the most common congenital anomalies in the United States. Periconceptional folic acid supplementation is a primary care-relevant preventive intervention. Objective: To review the evidence on folic acid supplementation for preventing neural tube defects to inform the US Preventive Services Task Force for an updated Recommendation Statement. Data Sources: MEDLINE, Cochrane Library, EMBASE, and trial registries through January 28, 2016, with ongoing surveillance through November 11, 2016; references; experts. Study Selection: English-language studies of folic acid supplementation in women. Excluded were poor-quality studies; studies of prepubertal girls, men, women without the potential for childbearing, and neural tube defect recurrence; and studies conducted in developing countries. Data Extraction and Synthesis: Two investigators independently reviewed abstracts, full-text articles, and risk of bias of included studies. One investigator extracted data and a second checked accuracy. Because of heterogeneity, data were not pooled. Main Outcomes and Measures: Neural tube defects, harms of treatment (twinning, respiratory outcomes). Results: A total of 24 studies (N > 58 860) were included. In 1 randomized clinical trial from Hungary initiated in 1984, incidence of neural tube defects for folic acid supplementation compared with trace element supplementation was 0% vs 0.25% (Peto odds ratio [OR], 0.13 [95% CI, 0.03-0.65]; n = 4862). Odds ratios from cohort studies recruiting participants between 1984 and 1996 demonstrated beneficial associations and ranged from 0.11 to 0.27 (n = 19 982). Three of 4 case-control studies with data from 1976 through 1998 reported ORs ranging from 0.6 to 0.7 (n > 7121). Evidence of benefit led to food fortification in the United States beginning in 1998, after which no new prospective studies have been conducted. More recent case-control studies drawing from data collected after 1998 have not demonstrated a protective association consistently with folic acid supplementation, with ORs ranging from 0.93 to 1.4 and confidence intervals spanning the null (n > 13 990). Regarding harms, 1 trial (OR, 1.40 [95% CI, 0.89-2.21]; n = 4767) and 1 cohort study (OR, 1.04 [95% CI, 0.91-1.18]; n = 2620) found no statistically significant increased risk of twinning. Three systematic reviews found no consistent evidence of increased risk of asthma (OR, 1.06 [95% CI, 0.99-1.14]; n = 14 438), wheezing, or allergy. Conclusions and Relevance: In studies conducted before the initiation of food fortification in the United States in 1998, folic acid supplementation provided protection against neural tube defects. Newer postfortification studies have not demonstrated a protective association but have the potential for misclassification and recall bias, which can attenuate the measured association of folic acid supplementation with neural tube defects. SN - 1538-3598 UR - https://www.unboundmedicine.com/medline/citation/28097361/Folic_Acid_Supplementation_for_the_Prevention_of_Neural_Tube_Defects:_An_Updated_Evidence_Report_and_Systematic_Review_for_the_US_Preventive_Services_Task_Force_ L2 - https://jamanetwork.com/journals/jama/fullarticle/10.1001/jama.2016.19193 DB - PRIME DP - Unbound Medicine ER -