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MICH-15 Data Details

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MICH-15 Reduce the proportion of women of childbearing potential who have lower (below the 25th percentile) red blood cell folate concentrations

About the Data

Description of the data source, numerator, denominator, survey questions, and other relevant details about the national estimate.

Data Source: 
National Health and Nutrition Examination Survey (NHANES); Centers for Disease Control and Prevention, National Center for Health Statistics (CDC/NCHS)
Changed Since the Healthy People 2020 Launch: 
Yes
Measure: 
percent
Baseline (Year): 
24.9 (2007–10)
Target: 
22.4
Target-Setting Method: 
10 percent improvement
Numerator: 

Number of non-pregnant women aged 15 to 44 years with red-blood-cell (RBC) folate concentration <337 ng/mL, below the 25th percentile of RBC concentrations among this group in 2007-2010

Denominator: 

Number of non-pregnant women aged 15 to 44 years with RBC concentrations

Comparable Healthy People 2010 Objective: 
Adapted from HP2010 objective
Data Collection Frequency: 
Periodic
Methodology Notes: 

    Lower RBC folate concentration is a population weighted estimate from the blood specimens collected from women aged 15 to 44 years as part of the standard NHANES protocol. According to data from the National Health and Nutrition Examination Survey (NHANES), median RBC folate concentrations increased substantially between 1988-94 and 1999-2000, pre- and post-fortification with folic acid, and then declined slightly in the post-fortification period (Pfeiffer et al., 2007, CDC, 2007).

Changes Between HP2010 and HP2020: 
This objective differs from Healthy People 2010 objective 16-16b in that objective 16-16b tracked the median RBC folate level among non-pregnant women aged 15–44 years, while this objective tracks the percentage of non-pregnant women aged 15–44 with an RBC folate level below the 25th percentile at baseline.

Revision History

Any change to the objective text, baseline, target, target-setting method or data source since the Healthy People 2020 launch.

Description of Changes Since the Healthy People 2020 Launch: 
In 2013, the baseline was revised from 24.5% (2003-06) to 24.9% (2007-10) because the assay that was used to measure RBC folate concentrations changed after the 2005-2006 NHANES cycle. Through survey year 2006 the Bio-Rad Quantaphase II radioassay (BR) was used, and from 2007 forward the microbiological assay (MA) was used. Although regression equations are provided in the NHANES documentation for converting BR values to MA values, they are dependent on methylenetetrahydrofolate reductase(MTHFR) genotype information, which is not available in the continuous NHANES data. MTHFR genotypes have been found to vary by race/ethnicity and without taking these differences into account the converted BR data do not reflect the true differences between race/ethnicity sub-groups. However, the MA does not have this issue and will be used in future NHANES. The target was adjusted from 22.1% to 22.4% to reflect the revised baseline using the original target-setting method. Also, the objective text was changed from ‘Reduce the proportion of women of childbearing potential who have low RBC folate concentrations’ to ‘Reduce the proportion of women of childbearing potential who have lower RBC folate concentrations.’ Finally the numerator was changed from ‘Number of non-pregnant women aged 15-44 years with red-blood-cell (RBC) foliate concentration <195 ng/ml, the 25th percentile of RBC concentrations among this group in 2003-2006’ to ‘Number of non-pregnant women aged 15-44 years with red-blood-cell (RBC) folate concentration <337 ng/mL, below the 25th percentile of RBC concentrations among this group in 2007-2010.’

References

Additional resources about the objective

  1. Blood Folate Levels: The Latest NHANES Results

  2. CDC. Folate status in women of childbearing age, by race/ethnicity---United States, 1999---2000, 2001-2002, and 2003-2004. MMWR 2007;55:1377-1380.
  3. Daly LE, Krik PN, Molloy A et al. Folate levels and neural tube defects. JAMA 1995;274:1698-1702.
  4. Pfeiffer CM, Johnson CL, Jain RB, et al. Trends in blood folate and vitamin B-12 concentrations in the United States, 1988-2004. Am J Clin Nutr; 86:718-27