Transcript CDC Growth Charts 2000 - Oklahoma State University

Reference Population: Standard Normal Curve
50th Percentile
5th
95th
Indicators of Nutritional Status
Head circumference-for-age
Stunting/shortness
length or height-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
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-'79)
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-'79)
HES III ('66-'70)
HES II ('63-'65)
14
16
18
20
NHANES I ('71-'74)
Exclusions from the Reference Data
• 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 and BMI-for-age curves
Age-Adjusted Prevalence of
Overweight* From NHANES I to III1
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
*>95th percentile BMI-for-age
1 Troiano et al, Arch Pediatr Adolesc Med 1995: 149: 1085-1091.
CDC Growth Charts Are for All
Racial and Ethnic Groups Combined
• The effect of race and ethnicity on growth is
controversial
• Inadequate sample data for racial- and ethnicspecific charts
• Environmental influences appear to contribute
to variations in growth but more research is
needed
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
1
Yip and Mei, 1995
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
• Separate charts are not recommended
• Working group of the World Health Organization
(WHO) is collecting data on infants following the
WHO feeding recommendations to develop charts
for infants and children through age 5.
Disjunction: Smoothed in New Charts
120
120
110
100
Length/height in cm
Length/height in cm
Old
110
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
New
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
• Birth to 36 months:
nationally representative
• Breast-fed and formula-fed infants
New Reference Curves Compared with Old Curves*
Prevalence of Nutrition Indicators
Birth to 36 Months
Nutrition Indicator
Change in Prevalence
Stunting/shortness
length-for-age <5th
2% to 4% lower from 6-24 mos
Underweight
weight-for-length <5th
3% to 5% higher
Overweight
weight-for-length >95th
Same
* NHANES III, PedNSS, WHO
New Reference Curves Compared with Old Curves*
Prevalence of Nutrition Indicators
Children 2 to 5 years of age
Nutrition Indicator
Change in Prevalence
Stunting/shortness
height-for-age <5
2% to 3% lower
Underweight** <5
3% to 5% higher
Overweight** 95th
3% to 5% higher
* NHANES III, PedNSS, WHO
**BMI-for-age, weight-for-stature
New in the CDC Growth Charts
 Charts extend to 20 years
 3rd and 97th percentiles available
 Lower limits of length (45 vs. 49 cm) and
height (77 vs. 90 cm) extended
 BMI-for-age charts (2-20 years) added
 85th percentile (at risk of overweight)
added
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 standards so 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
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 Growth Curves:
Weight-for-Stature versus BMI-for-Age
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 Differs by 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.
Can you see risk?
• This boy is 3 years, 3 weeks old.
• Is his BMI-for-age
- below the 5th percentile?
- 5th to <85th percentile: normal?
- >85th to <95th percentile: at risk
for overweight?
- >95th percentile: 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
- below the 5th percentile?
- 5th to <85th percentile: normal?
- >85th to <95th percentile: at
risk for overweight?
- >95th percentile: 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
- below the 5th percentile?
- 5th to <85th percentile: normal?
- >85th to <95th percentile: at
risk for overweight?
- >95th percentile: 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=
94thpercentile
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
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
Available CDC Growth Charts
•
Birth to 36 months
 Weight-for-length
 Length-for-age
 Weight-for-age
 Head circumference-for-age
Available CDC Growth Charts
•
2 to 20 years
 BMI-for-age
 Stature-for-age
 Weight-for-age
 Weight-for-height
Steps to Plot BMI-for-Age
• Select appropriate growth chart
• Record data
• Obtain accurate weight and height
measurements
• Calculate BMI
• Plot measurements
• Interpret plotted measurements
Case Study: “Sam”
•
•
•
•
•
Name: Sam
Weight: 37 lb 4 oz (16.9 kg)
Height: 41.5 inches (105 cm)
DOB (date of birth): 9/15/1994
DOV (date of visit): 4/4/1998
Data Entry Table for BMI-for-Age
Mother’s Height________
Father’s Height________
Date
4/4/98
Age
Weight
37 lb 4 oz
Gestational
Age________ Weeks
Height
41.5 in
BMI
Comment
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
Data Entry Table for BMI-for-Age
Mother’s Height________
Father’s Height________
Date
Age
Weight
4/4/98
3 1/2
37 lb 4 oz
Gestational
Age________ Weeks
Height
41.5 in
BMI
15.2
Comment
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
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
Future Directions for CDC Training
• Continuation of training at national
meetings
• Development of a Web-based training
module
• Training focus: accurate weighing and
measuring, calculating BMI, plotting
and interpreting the growth charts
Distribution of CDC Growth Charts
Electronic Copies
http://www.cdc.gov/growthcharts/