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  • Diagnostic accuracy of neonatal foot length to identify preterm and low birthweight infants: a systematic review and meta-analysis

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Original research
Diagnostic accuracy of neonatal foot length to identify preterm and low birthweight infants: a systematic review and meta-analysis
  1. Lian V Folger1,
  2. Pratik Panchal2,
  3. Michelle Eglovitch1,
  4. Rachel Whelan1,
  5. Anne CC Lee1
  1. 1Department of Pediatric Newborn Medicine; Global Advancement of Infants and Mothers (AIM) Lab, Brigham and Women's Hospital, Boston, Massachusetts, USA
  2. 2Translational Medicine, GI Drug Discovery Unit, Takeda Pharmaceuticals, Cambridge, Massachusetts, USA
  1. Correspondence to Dr Anne CC Lee; alee6{at}bwh.harvard.edu

Abstract

Introduction Eighty percent of neonatal deaths occur among babies born preterm and/or small for gestational age (SGA). In sub-Saharan Africa and South Asia, approximately 40% of births occur outside of health facilities, and gestational age (GA) and birth weight are commonly unknown. Foot length (FL) has been proposed as a simple, surrogate measurement to identify and triage small babies born in the community. We conducted a systematic review and meta-analysis of the diagnostic accuracy of newborn FL to classify preterm and low birthweight infants.

Methods PubMed, EMBASE, Cochrane, Web of Science, POPLINE and WHO Global Health Library databases were searched. Studies of live-born infants that compared FL with GA and/or birth weight were included. Data on diagnostic accuracy were summarised, described, and pooled, as appropriate.

Results Six hundred and two studies were identified and 41 included. Techniques for measuring FL included use of a firm plastic ruler, callipers, footprint or a measuring board. Twelve studies assessed the diagnostic accuracy of FL to identify preterm births; however, data were not pooled given heterogeneity and low quality of GA. 19 studies used FL to identify low birthweight infants (<2500 g, <2000 g). Among studies in Asia (n=3), FL <7.7 cm had pooled sensitivity and specificity of 87.6% (95% CI 61.1% to 99.0%) and 70.9% (95% CI 23.5% to 95.1%), respectively, to identify <2500 g infants. FL <7.3 cm had 82.1% (95% CI 63.7% to 92.2%) sensitivity and 82.1% (95% CI 59.2% to 90.8%) specificity for identifying <2000 g infants (n=3). In the African studies (n=3), FL <7.9 cm had pooled sensitivity and specificity of 92.0% (95% CI 85.6% to 95.7%) and 71.9% (95% CI 44.5% to 89.1%), respectively, to identify <2500 g neonates.

Conclusions FL is a simple proxy measure that can identify babies of low birthweight with high sensitivity, though somewhat lower specificity. Additional research is needed to determine the validity of FL to identify preterm infants, and understand the programmatic impact of screening on healthcare seeking and outcomes.

PROSPERO registration number CRD42015020499

  • systematic review
  • screening
  • paediatrics
  • child health
  • public health
https://creativecommons.org/licenses/by/4.0/

This is an open access article distributed in accordance with the Creative Commons Attribution 4.0 Unported (CC BY 4.0) license, which permits others to copy, redistribute, remix, transform and build upon this work for any purpose, provided the original work is properly cited, a link to the licence is given, and indication of whether changes were made. See: https://creativecommons.org/licenses/by/4.0/.

https://doi.org/10.1136/bmjgh-2020-002976

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    Footnotes

    • Handling editor Seye Abimbola

    • Contributors LVF coordinated and conducted screening and data extraction, assisted with designing search strings and data analysis, codrafted and revised the manuscript, and approved the final manuscript as submitted. PP designed the database searches, carried out initial screening and data extraction, and performed data analysis. He reviewed the manuscript, and approved the final manuscript as submitted. ME screened and extracted data, summarised data, reviewed and revised the manuscript, and approved the final manuscript as submitted. RW coordinated and supervised initial screening and data extraction, reviewed the manuscript, and approved the final manuscript as submitted. ACCL conceptualised and designed the study, coordinated and supervised data collection, completed secondary data extraction, conducted meta-analyses and codrafted and finalised the manuscript, and approved of the manuscript as submitted.

    • Funding This work was supported by the Bill & Melinda Gates Foundation through grant OPP1130198.

    • Competing interests None declared.

    • Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.

    • Patient consent for publication Not required.

    • Provenance and peer review Not commissioned; externally peer reviewed.

    • Data availability statement Data are available on request from the corresponding author.