10/1/20

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Using Z-Scores to Track AnthropometricMeasurements in Pediatrics

Jodi Wolff, MS, RDN, LD, FAND, FAACPDMPediatric Dietitian, Rainbow Babies and Children’s Hospital

Adjunct Professor, Case Western Reserve School of MedicineCleveland, OH, USA

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• Z-score: A number that indicates how far a data point is from the mean (average)

Curtis AE, et al. Aorta (Stamford). 2016;4(4):124-130.

What Is a Z-score?

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Why Use Z-scores vs Percentiles?

• Comparable across age and sex • Quantify growth outside of percentile ranges• More descriptive than “<2nd percentile or between the

25th and 50th percentiles”• Reflects small changes sooner than percentile• Better defines severity of malnutrition

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10/1/20

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-2.35

-5.14

<

<<

“Less Than the 2nd Percentile”

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-2 (2.3%)

-1 (15.9%)

0 (50%)

-3 (0.13%)

1 (84.1%)

2 (97.7%)

3 (99.8%)

Weight-for-Length Percentiles

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Degree of Malnutrition Z-scoreMild -1 to -1.99

Moderate -2 to -2.99Severe -3 or less

Becker PJ, et al. J Acad Nutr D iet. 2014;114(12):1988-2000.

Z-scores and Malnutrition

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