EAL

NGHC: Childhood Nutrition and Growth (2013)

Citation:

Study Design:

Class:

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Quality Rating:

Research Purpose:

The key objectives of this article are to provide an overview of the methods used to construct the standards for length/height-for-age, weight-for-age, weight-for-length/height and BMI-for-age, and to present some of the resulting curves.

Inclusion Criteria:

A minimum of three months of any breastfeeding was required for participants in the study's cross-sectional component
Children age 18 to 71 months
Breastfeeding support was available to mothers and ≥20% of mothers followed World Health Organization (WHO) feeding recommendations
No known health or environmental constraints to growth, mothers willing to follow Multicentre Growth Reference Study (MGRS) feeding recommendations, no maternal smoking before and after delivery, single term birth and absence of significant morbidity.

Exclusion Criteria:

To avoid the influence of unhealthy weights for length/height prior to constructing the standards, observations more or less than three standard deviations of the sample mean were excluded
The number of observations excluded for unhealthy weight-for-length/height was 185 (1.4%) for boys and 155 (1.1%) for girls, most of which were in the upper end of the cross-sectional sample distribution
A few influential observations for indicators other than weight-for-height were excluded when constructing the individual standards for boys and for girls.

Description of Study Protocol:

Recruitment

Data from the MGRS, which combines a longitudinal component from birth to 24 months with a cross-sectional component of children age 18 to 71 months, was used.

Design

Consensus report

Statistical Analysis

Two smoothing techniques were recommended for comparison by the expert group: cubic splines and fractional polynomials
Using GAMLSS, comparisons were carried out for length/height-for-age, weight-for-age and weight-for-length/height
For the length-for-age and weight-for-age standards, a power transformation applied to age prior to fitting was necessary to enhance the goodness of fit by the cubic splines technique
Percentile and z-score curves were generated, ranging from the 99th to the 1st percentile and from +3 to -3 standard deviations.

Data Collection Summary:

Timing of Measurements

Data to create the standards for length/height-for-age, weight-for-age, weight-for-length/height and BMI-for-age were derived from the MGRS population-based study from July 1997 to December 2003. This combined a longitudinal component from birth to 24 months with a cross-sectional component of children age 18 to 71 months.
Data-collection teams were trained at each site during the study's preparatory phase, at which time measurement techniques were standardized against one of the two MGRS anthropometry experts
For the longitudinal component of the study, screening teams measured newborns within 24 hours of delivery and follow-up teams conducted home visits until 24 months of age.

Dependent Variables

Standards for length/height-for-age, weight-for-age, weight-for-length/height and BMI-for-age.

Independent Variables

MGRS data included weight and head circumference at all ages, recumbent length, height, and arm circumference, triceps and subscapular skin folds.

Each observer independently measured and recorded a complete set of measurements, after which the two compared their readings
If any of the two readings exceeded the maximum allowable difference for a given variable, both observers once again independently measured and recorded a second and if necessary a third set of readings for the variable(s) in question
As part of the site-selection process in Ghana, India and Oman, surveys were conducted to identify socioeconomic characteristics that could be used to select groups whose growth was not environmentally constrained.

Description of Actual Data Sample:

Initial N: 6,697 children initially screened

Attrition (final N): 6,669 children (3,450 boys and 3,219 girls)

Age: Children age 18 to 71 months

Ethnicity: Not reported

Other relevant demographics: Not reported

Anthropometrics: Not reported

Location: Data collected from the United States, Ghana, India, Oman and Norway.

Summary of Results:

Key Findings

There was a wide variability in the degrees of freedom required for the cubic splines to achieve the best model
Except for length/height-for-age, which followed a normal distribution, all other standards needed to model skewness but not kurtosis
Length-for-age and height for age standards were constructed by fitting a unique model that reflected the 0.7cm average difference between these two measurements
The concordance between smoothed percentile curves and empirical percentiles was excellent and free of bias
Percentiles and z-score curves for boys and girls age 0 to 60 months were generated for weight-for-age, length/height for age, weight-for-length/height (45cm to 110cm and 65cm to 120cm, respectively) and BMI-for-age.

Author Conclusion:

The WHO Child Growth Standards depict normal growth under optimal environmental conditions and can be used to assess children everywhere regardless of ethnicity, socioeconomic status and type of feeding.

Funding Source:

Not-for-profit

World Health Organization (WHO)

Reviewer Comments:

Quality Criteria Checklist: Review Articles
Relevance Questions
	1.	Will the answer if true, have a direct bearing on the health of patients?	Yes
	2.	Is the outcome or topic something that patients/clients/population groups would care about?	Yes
	3.	Is the problem addressed in the review one that is relevant to dietetics practice?	Yes
	4.	Will the information, if true, require a change in practice?	Yes

Validity Questions
	1.	Was the question for the review clearly focused and appropriate?	Yes
	2.	Was the search strategy used to locate relevant studies comprehensive? Were the databases searched and the search termsused described?	Yes
	3.	Were explicit methods used to select studies to include in the review? Were inclusion/exclusion criteria specified andappropriate? Wereselectionmethods unbiased?	Yes
	4.	Was there an appraisal of the quality and validity of studies included in the review? Were appraisal methodsspecified,appropriate, andreproducible?	N/A
	5.	Were specific treatments/interventions/exposures described? Were treatments similar enough to be combined?	N/A
	6.	Was the outcome of interest clearly indicated? Were other potential harms and benefits considered?	Yes
	7.	Were processes for data abstraction, synthesis, and analysis described? Were they applied consistently acrossstudies and groups? Was thereappropriate use of qualitative and/or quantitative synthesis? Was variation in findings among studies analyzed? Were heterogeneity issued considered? If data from studies were aggregated for meta-analysis, was the procedure described?	Yes
	8.	Are the results clearly presented in narrative and/or quantitative terms? If summary statistics are used, are levels ofsignificance and/or confidence intervals included?	Yes
	9.	Are conclusions supported by results with biases and limitations taken into consideration? Are limitations ofthe review identified anddiscussed?	Yes
	10.	Was bias due to the review's funding or sponsorship unlikely?	Yes