TY - JOUR
T1 - Global birth prevalence of spina bifida by folic acid fortification status
T2 - A systematic review and meta-analysis
AU - Atta, Callie A.M.
AU - Fiest, Kirsten M.
AU - Frolkis, Alexandra D.
AU - Jette, Nathalie
AU - Pringsheim, Tamara
AU - St Germaine-Smith, Christine
AU - Rajapakse, Thilinie
AU - Kaplan, Gilaad G.
AU - Metcalfe, Amy
PY - 2016/1
Y1 - 2016/1
N2 - Background. Birth defects remain a significant source of worldwide morbidity and mortality. Strong scientific evidence shows that folic acid fortification of a region's food supply leads to a decrease in spina bifida (a birth defect of the spine). Still, many countries around the world have yet to approve mandatory fortification through government legislation. Objectives. Wesought to performa systematic reviewandmeta-analysis of period prevalence of spina bifida by folic acid fortification status, geographic region, and study population. Search methods. An expert research librarian used terms related to neural tube defects and epidemiology from primary research from 1985 to 2010 to search in EMBASE and MEDLINE. We searched the reference lists of included articles and key review articles identified by experts. Selection criteria. Inclusion criteria included studies in English or French reporting on prevalence published between January 1985 and December 2010 that (1) were primary research, (2) were population-based, and (3) reported a point or period prevalence estimate of spina bifida (i.e., prevalence estimate with confidence intervals or case numerator and population denominator). Two independent reviewers screened titles and abstracts for eligible articles, then2authorsscreenedfull texts induplicate forfinal inclusion. Disagreements were resolved through consensus or a third party. Data collection and analysis. We followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses, or PRISMA, abstracting data related to case ascertainment, study population, folic acid fortification status, geographic region, and prevalence estimate independently and in duplicate. We extracted overall data and any subgroups reported by age, gender, time period, or type of spina bifida. We classified each period prevalence estimate as mandatory or voluntary folic acid fortification according to each country's folic acid fortification status at the time data were collected (as determined by a well-recognized fortification monitoring body, Food Fortification Initiative).We determined study quality on the basis of sample representativeness, standardization of data collection and birth defect assessment, and statistical analyses. We analyzed study-level period prevalence estimates by using a random effects model (a level of < 0.05) for all meta-analyses. We stratified pooled period prevalence estimates by birth population, fortification status, and continent. Results. Of 4078 studies identified, we included 179 studies in the systematic reviewand123in ameta-analysis. Instudies of livebirths (LBs) alone, period prevalences of spina bifida were (1) lower in geographical regions with mandatory (33.86 per 100 000 LBs) versus voluntary (48.35 per 100000 LBs) folic acid fortification, and (2) lower in studies of LBs, stillbirths, and terminations of pregnancy in regionswithmandatory (35.22 per 100 000 LBs) versus voluntary (52.29 per 100 000 LBs) fortification. In LBs, stillbirths, and terminations of pregnancy studies, the lowest pooled prevalence estimate was in North America (38.70 per 100 000). Case ascertainment, surveillancemethods, and reporting varied across these population-based studies. Conclusions. Mandatory legislation enforcing folic acid fortification of the food supply lags behind the evidence, particularly in Asian and European countries. This extensive literature review shows that spina bifida is signifi-cantly more common in world regions without government legislation regulating full-coverage folic acid fortification of the food supply (i.e., Asia, Europe) and that mandatory folic acid fortification resulted in a lower prevalence of spina bifida regardless of the type of birth cohort. African data were scarce, but needed, asmany African nations are beginning to adopt folic acid legislation.
AB - Background. Birth defects remain a significant source of worldwide morbidity and mortality. Strong scientific evidence shows that folic acid fortification of a region's food supply leads to a decrease in spina bifida (a birth defect of the spine). Still, many countries around the world have yet to approve mandatory fortification through government legislation. Objectives. Wesought to performa systematic reviewandmeta-analysis of period prevalence of spina bifida by folic acid fortification status, geographic region, and study population. Search methods. An expert research librarian used terms related to neural tube defects and epidemiology from primary research from 1985 to 2010 to search in EMBASE and MEDLINE. We searched the reference lists of included articles and key review articles identified by experts. Selection criteria. Inclusion criteria included studies in English or French reporting on prevalence published between January 1985 and December 2010 that (1) were primary research, (2) were population-based, and (3) reported a point or period prevalence estimate of spina bifida (i.e., prevalence estimate with confidence intervals or case numerator and population denominator). Two independent reviewers screened titles and abstracts for eligible articles, then2authorsscreenedfull texts induplicate forfinal inclusion. Disagreements were resolved through consensus or a third party. Data collection and analysis. We followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses, or PRISMA, abstracting data related to case ascertainment, study population, folic acid fortification status, geographic region, and prevalence estimate independently and in duplicate. We extracted overall data and any subgroups reported by age, gender, time period, or type of spina bifida. We classified each period prevalence estimate as mandatory or voluntary folic acid fortification according to each country's folic acid fortification status at the time data were collected (as determined by a well-recognized fortification monitoring body, Food Fortification Initiative).We determined study quality on the basis of sample representativeness, standardization of data collection and birth defect assessment, and statistical analyses. We analyzed study-level period prevalence estimates by using a random effects model (a level of < 0.05) for all meta-analyses. We stratified pooled period prevalence estimates by birth population, fortification status, and continent. Results. Of 4078 studies identified, we included 179 studies in the systematic reviewand123in ameta-analysis. Instudies of livebirths (LBs) alone, period prevalences of spina bifida were (1) lower in geographical regions with mandatory (33.86 per 100 000 LBs) versus voluntary (48.35 per 100000 LBs) folic acid fortification, and (2) lower in studies of LBs, stillbirths, and terminations of pregnancy in regionswithmandatory (35.22 per 100 000 LBs) versus voluntary (52.29 per 100 000 LBs) fortification. In LBs, stillbirths, and terminations of pregnancy studies, the lowest pooled prevalence estimate was in North America (38.70 per 100 000). Case ascertainment, surveillancemethods, and reporting varied across these population-based studies. Conclusions. Mandatory legislation enforcing folic acid fortification of the food supply lags behind the evidence, particularly in Asian and European countries. This extensive literature review shows that spina bifida is signifi-cantly more common in world regions without government legislation regulating full-coverage folic acid fortification of the food supply (i.e., Asia, Europe) and that mandatory folic acid fortification resulted in a lower prevalence of spina bifida regardless of the type of birth cohort. African data were scarce, but needed, asmany African nations are beginning to adopt folic acid legislation.
UR - http://www.scopus.com/inward/record.url?scp=84951926014&partnerID=8YFLogxK
U2 - 10.2105/AJPH.2015.302902
DO - 10.2105/AJPH.2015.302902
M3 - Review article
C2 - 26562127
AN - SCOPUS:84951926014
SN - 0090-0036
VL - 106
SP - e24-e34
JO - American Journal of Public Health
JF - American Journal of Public Health
IS - 1
ER -