Assessing Child Growth Using Body Mass Index (BMI)

1
Assessing Child Growth Using the Body Mass Index
(BMI)-for-age Growth Charts A Training for
Health Care Providers
Adapted by the CHDP Bay Area Nutrition
Subcommittee (BANS) from Centers for Disease
Control and Prevention National Center for
Chronic Disease Prevention and Health
Promotion Division of Nutrition and Physical
Activity Maternal and Child Nutrition Branch
March 2006
2
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.

3
Training Objectives

• Understand BMI and how it is useful to screen for
  normal growth
• Learn how to plot BMI on the BMI-for-age growth
  charts
• Learn how to assess a childs growth using
  BMI-for-age growth charts for early
  identification of childhood overweight

4
Obesity Trends Among U.S. AdultsBRFSS, 1985
(BMI 30, or 30 lbs overweight for 5 4
person)
5
Obesity Trends Among U.S. AdultsBRFSS, 1986
(BMI 30, or 30 lbs overweight for 5 4
person)
6
Obesity Trends Among U.S. AdultsBRFSS, 1987
(BMI 30, or 30 lbs overweight for 5 4
person)
7
Obesity Trends Among U.S. AdultsBRFSS, 1988
(BMI 30, or 30 lbs overweight for 5 4
person)
8
Obesity Trends Among U.S. AdultsBRFSS, 1989
(BMI 30, or 30 lbs overweight for 5 4
person)
9
Obesity Trends Among U.S. AdultsBRFSS, 1990
(BMI 30, or 30 lbs overweight for 5 4
person)
10
Obesity Trends Among U.S. AdultsBRFSS, 1991
(BMI 30, or 30 lbs overweight for 5 4
person)
11
Obesity Trends Among U.S. AdultsBRFSS, 1992
(BMI 30, or 30 lbs overweight for 5 4
person)
12
Obesity Trends Among U.S. AdultsBRFSS, 1993
(BMI 30, or 30 lbs overweight for 5 4
person)
13
Obesity Trends Among U.S. AdultsBRFSS, 1994
(BMI 30, or 30 lbs overweight for 5 4
person)
14
Obesity Trends Among U.S. AdultsBRFSS, 1995
(BMI 30, or 30 lbs overweight for 5 4
person)
15
Obesity Trends Among U.S. AdultsBRFSS, 1996
(BMI 30, or 30 lbs overweight for 5 4
person)
16
Obesity Trends Among U.S. AdultsBRFSS, 1997
(BMI 30, or 30 lbs overweight for 5 4
person)
17
Obesity Trends Among U.S. AdultsBRFSS, 1998
(BMI 30, or 30 lbs overweight for 5 4
person)
18
Obesity Trends Among U.S. AdultsBRFSS, 1999
(BMI 30, or 30 lbs overweight for 5 4
person)
19
Obesity Trends Among U.S. AdultsBRFSS, 2000
(BMI 30, or 30 lbs overweight for 5 4
person)
20
Obesity Trends Among U.S. AdultsBRFSS, 2001
(BMI 30, or 30 lbs overweight for 5 4
person)
No Data lt10 1014 1519
2024 25
21
Obesity Trends Among U.S. AdultsBRFSS, 2002
(BMI 30, or 30 lbs overweight for 5 4
person)
(BMI ?30, or 30 lbs overweight for 54 person)
No Data lt10 1014 1519
2024 25
22
Obesity Trends Among U.S. AdultsBRFSS, 2003
(BMI 30, or 30 lbs overweight for 5 4
person)
No Data lt10 1014 1519
2024 25
23
Pediatric Nutrition Surveillance System (PedNSS)
Growth Statistics forCity and County of San
Francisco 2004BMI for age gt 95 for Children 2-4
Years
All Races 17.90
not enough data
24
Pediatric Nutrition Surveillance System (PedNSS)
Growth Statistics forCity and County of San
Francisco 2004BMI for age gt 95 for Children
5-19 Years
All Races 19.20
White 17.90
25
What is BMI?

• A number that compares a childs weight to her
  height
• Body Mass Index (BMI)
• Weight (kg) / Height (m)²
• BMI is an effective SCREENING tool alone it is
  not a diagnostic tool

26
BMI is Not the Same for Adults and Children

• Adult BMI is evaluated by use of cut-off numbers
  for example BMI gt30 is indicative of adult
  obesity
• There are no BMI cut-off numbers for children.
  The BMI number must be plotted on the BMI-for-age
  growth chart
• The BMI for children is useful only when it is
  plotted on the BMI-for-age Growth Chart

27
For Children, BMI Changes with Age
BMI
BMI
Example 95th percentile tracking Age
BMI 2 yrs 19.3 4 yrs 17.8 9 yrs
21.0 13 yrs 25.1
Boys 2 to 20 years
BMI
BMI
28
Importance of Using BMI-for-age

• Tracking tool for body size starting at age 2
  years through adulthood
• Only indicator that examines weight, stature AND
  age for a child on a single growth chart
• Correlates with clinical risk factors for chronic
  disease including hyperlipidemia, elevated
  insulin, and high blood pressure

29
BMI is Only an Indirect Measure of Body Fat
30
Using BMI-for-age Percentiles to Assess Risk

• gt 95th percentile Overweight
• 85th to lt 95th Risk of percentile overweight
• lt 5th percentile Underweight

31
What is a Percentile?
50th Percentile
85th
5th
95th
32
CDC Standardized Growth Chart
Formula to calculate BMI
Percentiles (5th,10th,25th, 50th,
75th,85th,90th,95th)
Published May 30, 2000
33
Using BMI-for-age Percentiles to Assess Risk

• gt 95th percentile Overweight?
• 85th to lt 95th Risk of percentile overweight?
• lt 5th percentile Underweight?
• Growth acceleration or deceleration across 2
  percentile lines

34
What is Adiposity Rebound (AR)?

• 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.

BMI
35
Normal Adiposity Rebound
Early Adiposity Rebound
BMI
BMI
36
Steps to Plot BMI-for-age

1. Obtain accurate weight and height measurements
2. Select the appropriate growth chart
3. Record the data
4. Calculate BMI
5. Plot measurements
6. Interpret plotted measurements

37

• Obtain Accurate Weight and Height Measurements
• Accurate Measurements are Critical

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 BMI17 BMI-for-age 85-94th tile
38
2. Select the Appropriate Growth Chart

• For ages birth to 36 months old
• Length-for-age, and Weight-for-age
• Weight-for-length, and Head Circumference-for-a
  ge
• For ages 2 to 20 years
• Weight-for-age, and Stature-for-age
• Body Mass Index BMI-for-age

39
3. Record Data
40
4. Calculate BMI
English Wt (lbs.) Ht (in.) Ht (in.) x
703 Metric Wt (kg.) Ht (cm.) Ht (cm.) x
10,000
41
4. Calculate BMI

• Use a Pediatric BMI Wheel

42
5. Plot Measurements
95th
85th
75th
50th
BMI
5th
Age
43
6. Interpret the BMI-for-age Chart

• Need a series of BMI plots to determine the
  growth trend
• If growth deviates from expected growth pattern,
  further assessment may be needed

44
Practice using BMI-for-age Growth Chart
Liz (4 y)
Pete (3 y)
Gabriella (4 y)
Photos from UC Berkeley Longitudinal Study, 1973
45
Please Plot Pete Perfectly
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
Photo from UC Berkeley Longitudinal Study, 1973
46
Answers Petes BMI-for-age
BMI18.3

• Interpretation
• BMI-for-age gt95th percentile
• Overweight
• Of 100 boys the same age, more than 95 have a
  lower BMI-for-age

47
Lets Look at Liz
Liz
48
Lizs - BMI
17.7
Liz
49
2-3-02
50
Graph Gabriellas Growth
51
Gabriellas BMI
52
(No Transcript)
53
Please Identify Overweight Children on PM160

Put comments here ex overweight, gt 95th
BMI
54
References

• Guidelines for Overweight in Adolescent
  Preventive Services (Am J Clin Nutr
  199459307-316)
• Obesity Evaluation and Treatment Expert
  Committee Recommendations (Pediatrics 1998
  Sept(102)3e 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)

55
Please visit www.cdc.gov/growthcharts/

• For additional training materials related to the
  growth charts
• For tools related to the growth charts
• To download the growth charts