Related Experiment Video
Updated: Mar 12, 2026

Assessment of Child Anthropometry in a Large Epidemiologic Study
Published on: February 2, 2017
Construction of Lambda, Mu, Sigma Values for Determining Mid-Upper Arm Circumference z Scores in U.S. Children Aged 2
Susan M Abdel-Rahman1, Charlie Bi2, Kristi Thaete3
11 University of Missouri, Kansas City-School of Medicine and Section of Therapeutic Innovation, Division of Clinical Pharmacology, Toxicology, and Therapeutic Innovation, Children's Mercy Hospital, Kansas City, Missouri, USA.
Insights
New Lambda Mu Sigma (LMS) values enable mid-upper arm circumference (MUAC) z-score calculations for U.S. children up to 18 years. This advances malnutrition assessment, improving pediatric nutrition monitoring.
Area of Science:
- Pediatric Nutrition
- Anthropometry
- Growth Monitoring
Background:
- Mid-upper arm circumference (MUAC) is a key indicator for malnutrition, outperforming BMI z scores in predicting morbidity and mortality.
- A consensus recommends MUAC z scores for U.S. children, but data for those over 5 years were lacking.
Purpose of the Study:
- To generate Lambda Mu Sigma (LMS) values for calculating MUAC z scores in U.S. children aged 2 months to 18 years.
- To provide essential data for comprehensive pediatric nutrition assessment.
Main Methods:
- Utilized National Health and Nutrition Examination Survey (1999-2012) anthropometric data (n=28,995) for model development.
- Constructed smoothed centiles and validated using independent U.S. MUAC datasets (n=1438).
- Assessed goodness-of-fit using visual and statistical methods, including detrended quantile-quantile plots and Q statistics.
Main Results:
- Generated LMS curves demonstrated excellent fit to the raw data across all age groups, including infants under 12 months.
- The derived curves aligned with existing CDC percentiles.
- The distribution of z scores closely approximated the expected 0 ± 1 across all age groups.
Conclusions:
- The developed LMS values provide a reliable method for clinicians to calculate MUAC z scores for U.S. children.
- This facilitates improved nutritional status monitoring and early identification of malnutrition in pediatric populations.
Background:
Mid-upper arm circumference (MUAC) has proven highly predictive of morbidity and mortality associated with malnutrition better, in some cases, than other growth indicators, including body mass index (BMI) z scores and weight-for-height z scores. A recent consensus statement recommended the inclusion of MUAC and MUAC z scores in the nutrition assessment of children in the United States; however, the requisite data to permit z score calculations for children aged >5 years have not been published.
Objective:
This investigation was designed to generate lambda mu sigma (LMS) values to permit the calculation of MUAC z scores in U.S. children 2 months through 18 years of age.
Design:
Anthropometric data from the Centers for Disease Control and Prevention (CDC) National Health and Nutrition Examination Survey (1999-2012) were used for model development (n = 28,995). Smoothed centiles were constructed and compared with previously described CDC percentiles. Independently collected MUAC data from 2 different U.S. studies were used for external validation (n = 1438).
Statistical Analyses:
Goodness-of-fit was assessed visually and statistically by examining detrended quantile-quantile plots, Q statistics, and the distribution of z scores.
Results:
The curves generated in this investigation fit the raw data well with no systematic bias and no sacrifice in fit for children aged <12 months. The curves were consistent with those published by the CDC, and the distribution z scores approximated 0 ± 1 in all age groups.
Conclusions:
These LMS values derived in this investigation can be used by clinicians to generate MUAC z scores for U.S. children.
Related Concept Videos
z Scores and Area Under the Curve
z Scores and Unusual Values
This score indicates how far a value is from the mean in terms of standard deviation. For example, if a data value has a z score of +1, the researcher can infer that the particular data value is one standard deviation above the mean. If another data...
Introduction to z Scores
z scores...
Introduction to z Scores
z scores...
Critical Values
Wald-Wolfowitz Runs Test II
For binary data, runs are identified using symbols such as + and −, or equivalently, 1s and 0s. In...

