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  3. A growth reference for mid upper arm circumference for age among school age children and adolescents, and validation for mortality: growth curve construction and longitudinal cohort study
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Research

A growth reference for mid upper arm circumference for age among school age children and adolescents, and validation for mortality: growth curve construction and longitudinal cohort study

BMJ 2017; 358 doi: https://doi.org/10.1136/bmj.j3423 (Published 03 August 2017) Cite this as: BMJ 2017;358:j3423
  1. Lazarus Mramba, statistician1,
  2. Moses Ngari, statistician2 3,
  3. Martha Mwangome, nutritional epidemiologist2,
  4. Lilian Muchai, nutritional epidemiologist2 4,
  5. Evasius Bauni, demographer2,
  6. A Sarah Walker, professor of medical statistics5 6,
  7. Diana M Gibb, professor of epidemiology5,
  8. Gregory Fegan, professor of clinical trials2 7,
  9. James A Berkley, professor of paediatric infectious diseases2 3 6
  1. 1Department of Medicine, University of Florida, FL, USA
  2. 2KEMRI/Wellcome Trust Research Programme, PO Box 230-80108, Kilifi, Kenya
  3. 3The Childhood Acute Illness & Nutrition (CHAIN) Network, Nairobi, Kenya
  4. 4Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya
  5. 5MRC Clinical Trials Unit, University College London, London, UK
  6. 6Nuffield Department of Medicine, University of Oxford, Oxford, UK
  7. 7Swansea Trials Unit, Swansea University Medical School, Swansea, UK
  1. Correspondence to: J A Berkley jberkley{at}kemri-wellcome.org
  • Accepted 10 July 2017

Abstract

Objectives To construct growth curves for mid-upper-arm circumference (MUAC)-for-age z score for 5-19 year olds that accord with the World Health Organization growth standards, and to evaluate their discriminatory performance for subsequent mortality.

Design Growth curve construction and longitudinal cohort study.

Setting United States and international growth data, and cohorts in Kenya, Uganda, and Zimbabwe.

Participants The Health Examination Survey (HES)/National Health and Nutrition Examination Survey (NHANES) US population datasets (age 5-25 years), which were used to construct the 2007 WHO growth reference for body mass index in this age group, were merged with an imputed dataset matching the distribution of the WHO 2006 growth standards age 2-6 years. Validation data were from 685 HIV infected children aged 5-17 years participating in the Antiretroviral Research for Watoto (ARROW) trial in Uganda and Zimbabwe; and 1741 children aged 5-13 years discharged from a rural Kenyan hospital (3.8% HIV infected). Both cohorts were followed-up for survival during one year.

Main outcome measures Concordance with WHO 2006 growth standards at age 60 months and survival during one year according to MUAC-for-age and body mass index-for-age z scores.

Results The new growth curves transitioned smoothly with WHO growth standards at age 5 years. MUAC-for-age z scores of −2 to −3 and less than−3, compared with −2 or more, was associated with hazard ratios for death within one year of 3.63 (95% confidence interval 0.90 to 14.7; P=0.07) and 11.1 (3.40 to 36.0; P<0.001), respectively, among ARROW trial participants; and 2.22 (1.01 to 4.9; P=0.04) and 5.15 (2.49 to 10.7; P<0.001), respectively, among Kenyan children after discharge from hospital. The AUCs for MUAC-for-age and body mass index-for-age z scores for discriminating subsequent mortality were 0.81 (95% confidence interval 0.70 to 0.92) and 0.75 (0.63 to 0.86) in the ARROW trial (absolute difference 0.06, 95% confidence interval −0.032 to 0.16; P=0.2) and 0.73 (0.65 to 0.80) and 0.58 (0.49 to 0.67), respectively, in Kenya (absolute difference in AUC 0.15, 0.07 to 0.23; P=0.0002).

Conclusions The MUAC-for-age z score is at least as effective as the body mass index-for-age z score for assessing mortality risks associated with undernutrition among African school aged children and adolescents. MUAC can provide simplified screening and diagnosis within nutrition and HIV programmes, and in research.

Footnotes

  • We thank the National Center for Health Statistics, National Health and Nutrition Examination Survey Data, Hyattsville, MD: US Department of Health and Human Services, Centers for Disease Control and Prevention for collecting and making publically available the HES/NHANES datasets and those who were examined in order to provide these data; the participants and clinical and research teams of the ARROW trial and Kilifi County Hospital for care provided, data collection and making the data available for this analysis; Mercedes de Onis, at the Growth Assessment and Surveillance Unit, Department of Nutrition, WHO for providing summary MUAC reference data for 60 to 71 month olds; and The BMJ reviewers, Saskia van der Kam, Dheeraj Shah, and Tim Cole, for their comments which led to a simpler modelling approach and an improved transition from WHO growth standards at as 5 years, as well as consideration of our findings in relation to currently used cut offs and the compromises involved in their use in operational settings.

  • Contributors: JAB conceived the study. JAB, LaM, GF and MN prepared the data to generate growth curves. LaM modelled the growth reference curves. SW and DG supervised the collection of the validation dataset from the ARROW trial. MN, MM, LiM and EB collected and processed the Kenyan validation dataset. MN and JAB performed the validation analysis. LaM and JAB wrote the first draft of the manuscript. All authors reviewed and critically edited the final manuscript and agree to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. JAB had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. JAB acts as guarantor of the study.

  • Funding: The funders had no role in the study design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

  • Competing interests: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf and declare: JAB has received financial support from the Wellcome Trust for the submitted work; ASW and DMG have received financial support from the MRC. All authors have no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.

  • Ethical approval: The NHES and NHANES surveys underwent internal human subjects review, but institutional review board approval using current standards was not obtained at that time. The ARROW trial was approved by the national regulatory and ethics review bodies in Uganda and Zimbabwe, and in the UK and Baylor University in the USA. The analysis of Kenyan data was approved by the Kenya Medical Research Institute (KEMRI) national ethical review committee.

  • Data sharing: The datasets used to construct MUAC z scores are freely available at www.cdc.gov/nchs/data_access/ftp_data.htm. The statistical code may be requested from Lazarus Mramba (Lazarus.Mramba@medicine.ufl.edu). Validation data from Kenya may be requested from the KEMRI//Wellcome Trust Research Programme Data Governance Committee (dgc@kemri-wellcome.org) and from the ARROW trial may be requested from Sarah Walker (rmjlasw@ucl.ac.uk).

  • Transparency: The lead author (JAB) affirms that the manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned have been explained.

This is an Open Access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 4.0) license, which permits others to distribute, remix, adapt and build upon this work, for commercial use, provided the original work is properly cited. See: http://creativecommons.org/licenses/by/4.0/.

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