Transcript CDC Growth Charts 2000 Centers for Disease Control and Prevention

CDC Growth Charts 2000
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
Revised June 2002
Training Objectives
• Science behind development of growth
charts
• Rationale for including BMI-for-age
• Using BMI-for-age as a screening tool
What growth charts are available?
New Features of the Growth Charts
• BMI-for-age charts (2-20 years)
• 85th percentile (at risk of overweight)
• 3rd and 97th percentiles available
• Lower limits of length (45 vs. 49 cm) and
height (77 vs. 90 cm) extended
• Smoothed percentile curves and z-scores
agree
• Correction in the disjunction
Disjunction: Smoothed in New Charts
120
120
1977
100
90
80
70
100
90
80
70
60
60
50
50
40
0
6
12 18 24 30 36 42 48 54 60
Age in month
2000
110
Length/height in cm
Length/height in cm
110
40
0
6
12 18 24 30 36 42 48 54 60
Age in month
Reference Population for
CDC Growth Charts
• Racially and ethnically diverse
• Infants: Birth to 36 months
• Children and Adolescents: 2 to 20
years
• Breast- and formula-fed infants
Reference Data Sets: Birth to 36 Months
Head Circum
Length
Weight
Weight-for-Length
B
3
6
9
12
15 18
Age in Months
21
24
27
30
33 36
MO/WI Natality
National Natality
PedNSS
Fels
NHANES III ('88-'94)
NHANES II ('76-'80)
NHANES I ('71-'74)
Reference Data Sets: 2 to 20 Years
Stature
Weight/BMI
2
4
6
8
10
Age in Years
12
NHANES III ('88-'94)
NHANES II ('76-'80)
NHES III ('66-'70)
NHES II ('63-'65)
14
16
18
20
NHES II ('63-65)
Exclusions from the Reference Data
• Very low birth weight (VLBW) infants
(<1500 g) were excluded because they
have different growth patterns
• NHANES III weight data for 6+ year olds
were excluded to avoid an upward shift
in weight-for-age and BMI-for-age curves
Age-Adjusted Prevalence of
Overweight1 From NHANES I to III 2
NHANES I
II
III
20
15
10
5
0
Boys 6-11 y Boys 12-17 y Girls 6-11 y Girls 12-17 y
Sex and Age Group
1>95th
percentile BMI-for-age
2 http://www.cdc.gov/nchs/products/pubs/pubd/hestats/overwght99.htm
CDC Growth Charts Are for All
Racial and Ethnic Groups Combined
• Environmental influences appear to contribute
to variations in growth more than genetic
influences
• Inadequate sample data for racial- and ethnicspecific charts
• The effect of race and ethnicity on BMI-forage is unclear
Age Adjusted Prevalence of Low Height-for-Age
by Ethnic Groups, Children Aged 0 to 5 Years1
15
10
White
Asian
5
0
79 80 81 82 83 84 85 86 87 88 89 90 91 92 93
Year of Visit
Mei, Yip and Trowbridge, Asia Pacific J Clin Nutr 1998; 7(2):
111-116
1
Breast-Fed vs. Formula-Fed Infants
• Mode of infant feeding can influence growth
• New charts represent the combined growth
patterns of breast-fed and formula-fed infants
• Working group of the World Health Organization
(WHO) is developing growth charts for infants and
children through age 5 using data collected on
infants following WHO feeding recommendations
Indicators of Nutritional Status
Head circumference-for-age
Stunting/shortness
length or stature-for-age
Underweight
weight-for-length
BMI-for-age
<5th percentile
>95th percentile
<5th percentile
<5th percentile
Indicators of Nutritional Status
Overweight
Weight-for-length
BMI-for-age
Risk of overweight
BMI-for-age
>95th percentile
85th to 95th percentile
Prevalence of Nutritional Status Indicators
New Reference Curves Compared with Old Curves*
< 2 Years Old
Nutrition Indicator
Change in Prevalence
Stunting/shortness
length-for-age <5th
1% to 2% lower
Underweight
weight-for-length <5th
1% to 2% higher
Overweight
weight-for-length >95th
2% lower for females
2% higher for males
* NHANES III
Prevalence of Nutritional Status Indicators
New Reference Curves Compared with Old Curves*
Children 2 to 5 years of age
Nutrition Indicator
Stunting/shortness
stature-for-age <5th
Change in Prevalence
1% lower
Underweight** <5th
3% to 4% higher
Overweight** 95th
No change for females
1% higher for males
* NHANES III
**BMI-for-age, weight-for-stature
What Is BMI?
• Body mass index (BMI) =
weight (kg)/height (m)2
• BMI is an effective screening tool; it is not a
diagnostic tool
• For children, BMI is age and gender specific,
so BMI-for-age is the measure used
Advantages of BMI-for-Age
 Provides a reference for adolescents that
was not previously available
 Consistent with adult index so it can be
used continuously from 2 years of age to
adulthood
 Tracks childhood overweight into
adulthood
Tracking BMI-for-Age from Birth to 18 Years with
Percent of Overweight Children who Are Obese at Age 251
100
BMI < 85th
BMI >=85th
BMI >=95th
% obese as adults
83
80
69
60
77
75
67
55
52
36
40
26
20
16 17
15
19
12
11
10
9
0
Birth
1 to 3
3 to 6
6 to 10
Age of child (years)
Whitaker et al. NEJM: 1997;337:869-873
10 to 15
15 to 18
Advantages of BMI-for-Age
 BMI-for-age relates to health risks
 Correlates with clinical risk factors for
cardiovascular disease including hyperlipidemia,
elevated insulin, and high blood pressure
 BMI-for-age during pubescence is related to
lipid levels and high blood pressure in middle
age
BMI-for-Age Compares Well with
• Weight-for-stature measurements
• Measures of body fat
Mei et al., Am J Clin Nutr 2002;75:978-85.
1
Why Use BMI-for-Age?
• Recommended by expert committees to
evaluate overweight
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)
Shape of Weight-for-Stature Curve
versus BMI-for-Age Curve
35
30
25
5th
20
15
10
95th
30
50th
BMI
Weight (kg)
35
95th
25
50th
20
5th
15
5
10
0
80
90
100 110 120 130
Stature (cm)
24
72 120 168 216
Age (months)
For Children, BMI Changes with Age
BMI
BMI
Example: 95th
Percentile Tracking
Boys: 2 to 20 years
BMI
BMI
Age
BMI
2 yrs
4 yrs
9 yrs
13 yrs
19.3
17.8
21.0
25.1
BMI
BMI
Boys: 2 to 20 years
Shape of BMI-forAge Growth Curve:
“Adiposity” Rebound
(AR)
Example: Early AR
Age (mos)
26
32
38
41
BMI
BMI
BMI
BMI
18.2
17.4
18.5
18.7
BMI-for-Age Cutoffs
> 95th percentile
Overweight
85th to < 95th
percentile
Risk of overweight
< 5th percentile
Underweight
Performance of BMI-for-Age
as a Screening Tool
• Using the 85th and 95th percentiles as cut points,
few children are incorrectly identified as over-fat
but some over-fat children will be missed.
• It is desirable to correctly identify those children
not at risk of overweight or overweight.
Calculating BMI with the Metric System
Formula: weight (kg)/[height (m)]2
Calculation: [weight (kg)/ height (cm)/
height (cm)] x 10,000
Example: A child’s weight=16.9 kg and height=105.4 cm
BMI = [16.9 kg / 105.4 cm / 105.4 cm] x 10,000 = 15.2
Calculating BMI with the English System
Formula: weight (lb)/[height (in)]2 x 703
Calculation: [weight (lb)/height (in)/height (in)] x 703
Example: A child’s weight = 37 pounds, 4 ounces and
height = 41 1/2 inches
(convert fractions to decimal value)
BMI = [37.25 lb / 41.5 in / 41.5 in] x 703 = 15.2
Can you see risk?
• This boy is 3 years, 3 weeks old.
• Is his BMI-for-age
- >85th to <95th percentile:
at risk for overweight?
Photo from UC Berkeley Longitudinal Study, 1973
Plotted BMI-for-Age
BMI
BMI
Boys: 2 to 20 years
Measurements:
Age=3 y 3 wks
Height=100.8 cm
(39.7 in)
Weight=18.6 kg
(41 lb)
BMI=18.3
BMI
BMI-for-age=
>95th percentile
overweight
BMI
Can you see risk?
• This girl is 4 years, 4 weeks old.
• Is her BMI-for-age
- >85th to <95th percentile:
at risk for overweight?
Photo from UC Berkeley Longitudinal Study, 1974
Plotted BMI-for-Age
BMI
Girls: 2 to 20 years
BMI
Measurements:
Age= 4 y 4 wks
Height=106.4 cm
(41.9 in)
Weight=15.7 kg
(34.5 lb)
BMI=13.9
BMI-for-age=
10th percentile
Normal
BMI
BMI
Can you see risk?
• This girl is 4 years old.
• Is her BMI-for-age
- >85th to <95th percentile:
at risk for overweight?
Photo from UC Berkeley Longitudinal Study, 1973
Plotted BMI-for-Age
BMI
BMI
Girls: 2 to 20 years
Measurements:
Age=4 y
Height=99.2 cm
(39.2 in)
Weight=17.55 kg
(38.6 lb)
BMI=17.8
BMI-for-age= between
90th –95th percentile
BMI
BMI
At risk for overweight
Accurate Measurements are Critical
BMI
BMI
Boys: 2 to 20 years
5 1/2 year old boy
Weight: 41.5 lb
Height: 43 in
BMI= 15.8
BMI-for-age=50th %tile
Inaccurate height
measurement: 42.25
BMI=16.3
BMI
BMI
BMI-for-age=75th %tile
Interpreting the BMI-for-Age Cutoffs
> 95th percentile
Overweight
85th to < 95th
percentile
Risk of overweight
< 5th percentile
Underweight
Interpreting the BMI-for-Age Chart
• BMI-for-age indicates a child’s weight in
relation to his/her height for a specific age
and gender
• Need a series of BMI plots to determine
the growth trend
• If indices deviate from normal growth
patterns, further assessment may be
needed
Example: “Sam”
•
•
•
•
•
Name: Sam
Weight: 37 lb 4 oz (16.9 kg)
Height: 41.5 inches (105 cm)
Age: 3.5 years
BMI: 15.2
Sam’s BMI Plotted on Boy’s BMI-for-Age Chart
BMI
BMI
Interpretation:
Boys: 2 to 20 years
• Sam’s BMI-for-age is
slightly below the 25th
%tile so it falls within
the normal range.
• Of 100 boys who are
the same age, fewer than
25 have a BMI-for-age
lower than Sam’s.
BMI
BMI
Summary of Using BMI-for-Age
• BMI-for-age is the recommended method
for screening overweight and underweight
• For children, BMI is age and gender
specific; for adults there are fixed cut
points
• Accurate and periodic measurements are
important elements of any anthropometric
screening
Steps to Plot BMI-for-Age
• Obtain accurate weight and height
measurements
• Select the appropriate growth chart
• Record the data
• Calculate BMI
• Plot measurements
• Interpret plotted measurements
Please visit:
http://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
www.cdc.gov/growthcharts