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Utility of Population Attributable Fraction Assessment in Guiding Interventions to Reduce Low Birthweight in the High-Altitude State of Colorado

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Abstract

Objectives We evaluated the ability of population attributable fraction (PAF) assessments to alter significant modifiable risks for low birthweight (LBW) and the impact of high altitude as a risk for LBW in Colorado. Methods Logistic regression analysis of birth certificate parameters in 1995–1997 identified risk factors for PAF assessment. PAF for birth at high altitude, multiple births, and LBW in singleton births were determined. Subsequent analysis of singleton LBW risks, using number needed to treat (NNT) analysis, estimated how elimination of major modifiable risk factors could reduce LBW in the study population. Public health interventions were initiated and PAF analysis conducted 12 years afterward to determine the effect of interventions. Results PAF in singleton births revealed low maternal weight gain in pregnancy and maternal smoking as the greatest modifiable attributable risk factors for LBW (12.7/12.5 %, respectively, in 1995–1997 and 12.9/7.1 % in 2007–2009). Significant interaction between these variables resulted in PAF of 34.4 % when the two occurred together in 1995–1997, decreasing to 19.4 % in 2007–2009. NNT analysis of singleton births in 1995–1997 revealed that eliminating low maternal weight gain, smoking, late prenatal care in all women and interpregnancy intervals <1 year in multiparous women reduced LBW by 46.5 %. The respective proportional reductions in PAF of 40.3 and 46.3 % for maternal smoking and weight gain/smoking interaction were associated with a 1.4 % LBW reduction in singleton births between the two study periods. Conclusions for Practice PAF and NNT analyses are valuable tools to predict intervention targets to lower LBW.

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Acknowledgments

The authors gratefully acknowledge the assistance of Kirk Bol, Acting State Registrar for Vital Statistics, CDPHE, with providing birth certificate data and Barbara Gabella, Epidemiologist in Maternal Child Health, CDPHE, for guidance with population attributable fraction analyses.

Funding

This study was conducted as a part of routine public health practice with the Colorado Title V program without special funding.

Author information

Author notes

  1. Janice French

    Present address: Los Angeles Best Babies Collaborative, Center for Healthy Births, 350 South Bixel Street, Suite 100, Los Angeles, CA, 90017, USA

Authors and Affiliations

  1. PATH, 2201 Westlake Avenue, Seattle, WA, 98121, USA

    G. William Letson

  2. Colorado Department of Public Health and Environment, 4300 Cherry Creek Drive South, Denver, CO, 80246-1530, USA

    Sue Ricketts, Karen Trierweiler & Ashley Juhl

  3. Boulder County Public Health, Boulder, CO, USA

    Indira Gujral

  4. Private Practice, San Diego, CA, USA

    Linda Archer & James A. McGregor

Authors
  1. G. William Letson
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  2. Janice French
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  4. Karen Trierweiler
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Corresponding author

Correspondence to G. William Letson.

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Ethical approval

Publicly available, de-identified birth certificate records were used in accord with public health ethical standards.

Conflict of interest

None of the authors has a conflicting financial interest regarding this study. This study is not otherwise submitted for publication. The authors were all public health employees at the time and have no fiscal conflicts to declare.

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Letson, G.W., French, J., Ricketts, S. et al. Utility of Population Attributable Fraction Assessment in Guiding Interventions to Reduce Low Birthweight in the High-Altitude State of Colorado. Matern Child Health J 20, 2457–2464 (2016). https://doi.org/10.1007/s10995-016-2037-6

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  • DOI: https://doi.org/10.1007/s10995-016-2037-6

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