Table 1.

Data inputs and sources for estimated number of neural tube defects (NTDs) that could be prevented with fortification of corn masa flour

	Race/ethnic group	Spina bifida	Anencephaly	Data Source
Prevalence of NTD/10,000 live births before mandatory folic acid fortification of ECGP (95% CI)a	Hispanic	6.49 (5.73, 7.25)	3.85 (3.26, 4.43)	Williams et al. Pediatrics 2005 (8)
	Non-Hispanic white	5.13 (4.77, 5.49)	2.79 (2.52, 3.05)
	Non-Hispanic black	3.57 (2.98, 4.16)	1.98 (1.55, 2.42)
Prevalence of NTD/10,000 live births after mandatory folic acid fortification of ECGP (95% CI)a	Hispanic	4.18 (3.87, 4.49)	2.84 (2.58, 3.09)	Williams et al. Pediatrics 2005 (8)
	Non-Hispanic white	3.37 (3.18, 3.56)	1.98 (1.84, 2.13)
	Non-Hispanic black	2.90 (2.56, 3.24)	1.80 (1.53, 2.06)
Increase in the median daily usual total folateb intake with folic acid fortification of ECGP (95% CI)c	Mexican Americanc	156μg (87 μg, 225μg)		Bentley et al. American Journal of Public Health 2006 (26)
	Non-Hispanic white	116μg (47 μg, 185μg)
	Non-Hispanic black	101μg (32 μg, 170μg)
Increase in the median daily usual total folic acid intake with folic acid fortification of corn masa flour (95% CI)e	Mexican Americanc,d	41μg (0μg, 90μg)		Hamner et al. Public Health Nutrition 2012 (17)
	Non-Hispanic white	11μg (0μg, 46μg)
	Non-Hispanic black	11μg (0μg, 57μg)
Annual number of live births	Hispanic	1,041,239		Martin et al. National Vital Statistics Reports 2010 (45)
	Non-Hispanic white	2,267,817
	Non-Hispanic black	623,029

Abbreviations: ECGP = enriched cereal grain products; CI = confidence interval

^aStandard error estimates were not provided in the referenced publication; they were therefore estimated under a Poisson assumption using the equation: $\sqrt{\mathit{number}of\mathit{NTDs}/{(\mathit{number}of\mathit{live}\mathit{births})}^2}$

^b“Total folate” includes sum of naturally-occurring food folate and synthetic folic acid, with no adjustment for differences in bioavailability

^cThe term “Hispanic” is used for rates of NTDs, because that is how the data were collected in the cited publication. However, folic acid intake data that can be generalized to the US population are only available for Mexican Americans. Mexican Americans make up approximately 63% of all Hispanics in the United States (18).

^dStandard error estimates were not provided in the reference publication. For purposes of the Monte Carlo simulation a conservative estimate of 25 μg was used for the standard error of each estimate of the median usual daily folic acid intake. This value was selected based on external estimates of median usual daily folic acid intake by race/ethnicity using NHANES data. The equation used to estimate the standard error for the difference between the estimates was $\sqrt{SE{({\mathit{median}}_1)}^2+SE{({\mathit{median}}_2)}^2}$

^eLower bound set to 0 because fortification with folic acid was assumed to have a non-negative impact on intake.