Assessing Child Growth Using the Body Mass Index (BMI)-for-age Growth Charts: A Training for Health...

Assessing Child Growth Using the

Body Mass Index (BMI)-for-age Growth Charts:

A Training for Health Care ProvidersAdapted by the CHDP Bay Area Nutrition Subcommittee

(BANS) from

Centers for Disease Control and PreventionNational Center for Chronic Disease Prevention and Health

Promotion

Division of Nutrition and Physical Activity

Maternal and Child Nutrition BranchMarch 2006

BMI-for-age Growth Chart is:BMI-for-age Growth Chart is:

considered standard practice by the American Academy of Pediatrics.

now required as part of the well-child exam for children ages 2 through 19 by the Child Health and Disability Prevention (CHDP) Program.

Training ObjectivesTraining Objectives

Understand BMI and how it is useful to Understand BMI and how it is useful to screen for normal growthscreen for normal growth

Learn how to plot BMI on the BMI-for-Learn how to plot BMI on the BMI-for-age growth chartsage growth charts

Learn how to assess a child’s growth Learn how to assess a child’s growth using BMI-for-age growth charts for using BMI-for-age growth charts for early identification of childhood early identification of childhood overweightoverweight

Source: Behavioral Risk Factor Surveillance System, CDC.

Obesity Trends* Among U.S. AdultsBRFSS, 1985

No Data <10% 10%–14%

(*BMI ≥30, or ~ 30 lbs overweight for 5’ 4” person)



No Data <10% 10%–14%




No Data <10% 10%–14% 15%–19%




No Data <10% 10%–14% 15%–19% ≥20




No Data <10% 10%–14% 15%–19% 20%–24% ≥25%



(*BMI 30, or ~ 30 lbs overweight for 5’4” person)

No Data <10% 10%–14% 15%–19% 20%–24% ≥25%




Obesity* Trends Among U.S. AdultsBRFSS, 2003


No Data <10% 10%–14% 15%–19% 20%–24% ≥25%

Hispanic 22.50%

Asian/PI 11.90%

Black15.60%

0%

10%

20%

30%

40%

50%HispanicAsian/PIBlackWhiteAll Races

All Races

17.90%

not

en

ough

dat

a

Pediatric Nutrition Surveillance System (PedNSS) Growth Pediatric Nutrition Surveillance System (PedNSS) Growth Statistics forStatistics for

City and County of San Francisco 2004City and County of San Francisco 2004BMI for age > 95% for Children 2-4 YearsBMI for age > 95% for Children 2-4 Years

Hispanic 26.60%

Asian/PI 11.40%

Black 24.90%

0%

10%

20%

30%

40%

50%HispanicAsian/PIBlackWhiteAll Races

All Races

19.20%

White 17.90%

Pediatric Nutrition Surveillance System (PedNSS) Growth Pediatric Nutrition Surveillance System (PedNSS) Growth Statistics forStatistics for

City and County of San Francisco 2004City and County of San Francisco 2004BMI for age > 95% for Children 5-19 YearsBMI for age > 95% for Children 5-19 Years

A number that compares a A number that compares a child’s weight to her heightchild’s weight to her height

Body Mass Index (BMI) = Body Mass Index (BMI) =

Weight (kg) / Height (m)²Weight (kg) / Height (m)²

BMI is an effective BMI is an effective SCREENING tool; alone it is nottool; alone it is not a diagnostic a diagnostic tooltool

What is BMI?What is BMI?

BMI is Not the Same for BMI is Not the Same for Adults and ChildrenAdults and Children

Adult BMI is evaluated by use of cut-off Adult BMI is evaluated by use of cut-off numbers; for example BMI >30 is numbers; for example BMI >30 is indicative of adult obesityindicative of adult obesity

There are no BMI cut-off numbers for There are no BMI cut-off numbers for children. The BMI number must be plotted children. The BMI number must be plotted on the BMI-for-age growth charton the BMI-for-age growth chart

The BMI for children is useful only when it The BMI for children is useful only when it is plotted on the is plotted on the “BMI-for-age Growth “BMI-for-age Growth Chart”Chart”

Example: 95th percentile tracking Age BMI 2 yrs 19.3 4 yrs 17.8 9 yrs 21.013 yrs 25.1

For Children, BMI Changes with Age

Boys: 2 to 20 years

BMI BMI

BMI BMI

Tracking tool for body size starting Tracking tool for body size starting at age 2 years through adulthoodat age 2 years through adulthood

Only indicator that examines weight, Only indicator that examines weight, stature AND age for a child on a stature AND age for a child on a single growth chartsingle growth chart

Correlates with clinical risk factors Correlates with clinical risk factors for chronic disease including for chronic disease including hyperlipidemia, elevated insulin, and hyperlipidemia, elevated insulin, and high blood pressurehigh blood pressure

Importance of Using BMI-for-Importance of Using BMI-for-ageage

BMI is Only an Indirect BMI is Only an Indirect Measure of Body FatMeasure of Body Fat

> 95th percentile Overweight

85th to < 95th Risk of percentileoverweight

< 5th percentileUnderweight

Using BMI-for-age Percentiles to Assess Risk

What is a What is a Percentile?Percentile?

95th

5th

50th Percentile

85th

CDC CDC StandardizeStandardized d Growth Growth ChartChart

Formula to calculate BMI

Published May 30, 2000

Percentiles (5th,10th,25th, 50th, 75th,85th,90th,95th)

> 95th percentileOverweight?

85th to < 95th Risk of percentile overweight?

< 5th percentileUnderweight?

Growth acceleration or deceleration across 2 percentile lines

Using BMI-for-age Percentiles to Assess Risk

What is “Adiposity” Rebound (AR)?

BMI

•A rebound or increase in BMI that occurs after it reaches its lowest point, usually between ages 4 to 6.

• Normal pattern of growth

• An early "adiposity" rebound, occurring before ages 4 to 6, is associated with obesity in adulthood.

Normal “Adiposity”

Rebound

BMI BMI

Early “Adiposity”

Rebound

Steps to Plot BMI-for-ageSteps to Plot BMI-for-age1.1. Obtain accurate weight and Obtain accurate weight and

height measurements height measurements

2.2. Select the appropriate growth Select the appropriate growth chartchart

3.3. Record the dataRecord the data

4.4. Calculate BMICalculate BMI

5.5. Plot measurementsPlot measurements

6.6. Interpret plotted Interpret plotted measurementsmeasurements

5 year old boy

Weight: 43.5 lb

Height: 43 in

BMI= 16.5

BMI-for-age = 75-84th %tile

Inaccurate height measurement: 42.5 in

BMI=17

BMI-for-age = 85-94th %tile

1. Obtain Accurate Weight and Height Measurements

Accurate Measurements are Critical

Boys: 2 to 20 years

BMI BMI

BMI BMI

2. Select the Appropriate 2. Select the Appropriate Growth ChartGrowth Chart

For ages birth to 36 months old:For ages birth to 36 months old:““Length-for-age,” and “Weight-for-age” Length-for-age,” and “Weight-for-age” ““Weight-for-length,” and “Head Weight-for-length,” and “Head

Circumference-for-age” Circumference-for-age”

For ages 2 to 20 years: For ages 2 to 20 years: ““Weight-for-age,” and “Stature-for-age”Weight-for-age,” and “Stature-for-age”Body Mass Index “BMI-for-age”Body Mass Index “BMI-for-age”

3. Record Data3. Record Data

4. Calculate BMI4. Calculate BMI

English:

Wt (lbs.) ÷Ht (in.) ÷ Ht (in.) x 703

Metric: Wt (kg.) ÷Ht (cm.) ÷ Ht (cm.) x 10,000

4. Calculate BMI4. Calculate BMI

Use a Pediatric BMI WheelUse a Pediatric BMI Wheel

5. Plot Measurements5. Plot Measurements

Age

BMI

50th

75th

85th

5th

95th

6. Interpret the BMI-for-age Chart6. Interpret the BMI-for-age Chart

Need a series of BMI plots to Need a series of BMI plots to determine the growth trenddetermine the growth trend

If growth deviates from If growth deviates from expected growth pattern, expected growth pattern, further assessment may be further assessment may be neededneeded

Practice using Practice using “BMI-for-age” Growth Chart“BMI-for-age” Growth Chart

Liz (4 y)Pete (3 y) Gabriella (4 y)Photos from UC Berkeley Longitudinal Study, 1973

Please Plot Pete Perfectly

Photo from UC Berkeley Longitudinal Study, 1973

Measurements for Pete:

Age= 3 y 3 wks

Weight= 41 lbs (18.6 kg)

Height= 39.7 in (100.8 cm)

Find BMI, plot, & interpret growth trend

BMI= Wt ( lbs) ÷ Ht (in) ÷ Ht (in) x 703

BMI=18.3

Boys: 2 to 20 years

BMI BMI

BMI BMI

Interpretation:

• BMI-for-age = >95th

percentile

• Overweight

• Of 100 boys the same age, more than 95 have a lower BMI-for-age

Answers: Pete’s “BMI-for-age”

Let’s Look at LizLet’s Look at Liz

Liz

Liz’s - BMILiz’s - BMI

Liz

17.7

2-3-02

Graph Gabriella’s Growth Graph Gabriella’s Growth

Gabriella’s BMI Gabriella’s BMI

Please Identify Overweight Please Identify Overweight Children on PM160Children on PM160

Put comments here

ex: overweight, > 95th % BMI

Guidelines for Overweight in Adolescent Preventive Services (Am J Clin Nutr 1994;59:307-316)

Obesity Evaluation and Treatment: Expert Committee Recommendations (Pediatrics 1998 Sept;(102)3:e 29)

Assessment of Childhood and Adolescent Obesity: International Obesity Task Force (Am J Clin Nutr 1999, 70,suppl)

Centers for Disease Control and Prevention Website (www.cdc.gov/growthcharts)

American Academy of Pediatrics Policy Statement: Prevention of Pediatric Overweight and Obesity (Pediatrics 2003 Aug (112)2; 424-430)

References

• For additional training materials related to the growth charts

• For tools related to the growth charts

• To download the growth charts

Please visit:

www.cdc.gov/growthcharts/

Assessing Child Growth Using the Body Mass Index (BMI)-for-age Growth Charts: A Training for Health...

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