Structured Abstract
Please note: In 2003, the CTF updated its Grades of
Recommendations to include an "I Recommendation" for situations where
insufficient evidence exists to allow a recommendation to be made.
(Formerly, these situations were captured under a "C
Recommendation".) This change is not retroactive, and all
"C Recommendations" made prior to 2003 have not been
reevaluated in light of the new "I" recommendation grade. For a
discussion of these recommendation grades, please link to the 2003 article in
the Canadian Medical Association Journal here.
Screening for Childhood Obesity
Prepared by William Feldman, MD, FRCPC, Department of Pediatrics, University
of Toronto, and Brenda L. Beagan, MA, Research Associate, Canadian Task
Force from 1990-1992
These recommendations were finalized by the Task Force in November
1992
Contents
Objective
To make recommendations for screening and treating Canadian infants and
children for obesity. This is an update of the 1979 Canadian Task Force
guideline.
Burden
of Suffering
Estimates of Canadian prevalence rates for childhood obesity range from
7% to 43%, depending on whether the basis is self–reports or objective
measures, and on what measure of obesity is used. An inverse relationship
has been shown between social class and prevalence of obesity in children
aged 3–18 years, with rates ranging from 25% in low income families to
5% in high income families. Fewer than 5% of obese children have
an underlying disease producing obesity, however, several disease conditions
can cause obesity, including endocrinopathies, central nervous system diseases,
and specific congenital syndromes. Severe obesity has been linked
to increased mortality in adults, but there is no association between moderate
childhood obesity and increased mortality, unless other risk factors are
present. However, obese children may suffer significant social and
psychological difficulties. Stigmatization and discrimination in
academic and social settings may lead to a negative body image and low
self-esteem, possibly resulting in the development of eating disorders
such as anorexia nervosa in adolescence.
Options
Screening options include height-and-weight growth charts for infants,
body weight, body-mass index, and triceps and subscapular skin-fold thickness
measurements. Treatment options include low calorie diets, increased exercise,
behavioural modification, and education of parents and children. Very low
calorie diets that can impair growth and development and invasive treatment
options (surgery, pharmacotherapy and gastric balloons) are not included
in this guideline.
Outcomes
Obesity and reductions in obesity including weight loss.
Evidence
MEDLINE was searched for 1981 - 1991 using the keywords child and obesity
and bibliographies of relevant articles were checked.
Recommendations were graded as:
|
A
|
Good evidence to support the recommendation that the condition
be specifically considered in a PHE. |
|
B
|
Fair evidence to support the recommendation that the condition
be specifically considered in a PHE. |
|
C
|
Poor evidence regarding inclusion or exclusion of the condition
in a PHE, but recommendations may be made on other grounds. |
|
D
|
Fair evidence to support the recommendation that the condition
be specifically excluded from consideration in a PHE. |
|
E
|
Good evidence to support the recommendation that the condition
be specifically excluded from consideration in a PHE. |
Quality of evidence was rated according to 5 levels:
|
I
|
Evidence from at least 1 properly randomized controlled
trial (RCT). |
|
II-1
|
Evidence from well-designed controlled trials without randomization. |
|
II-2
|
Evidence from well-designed cohort or case-control analytic
studies, preferably from more than 1 centre or research group. |
|
II-3
|
Evidence from comparisons between times or places with
or without the intervention. Dramatic results in uncontrolled experiments
could also be included here. |
|
III
|
Opinions of respected authorities, based on clinical experience,
descriptive studies or reports of expert committees. |
Values
The 13-member Task Force of experts in family medicine, geriatric medicine,
pediatrics, psychiatry and epidemiology used an evidence-based method for
evaluating the effectiveness of preventive health care interventions. Recommendations
were not based on cost-effectiveness of options. Patient preferences were
not discussed.
Background papers providing critical appraisal of the evidence and tentative
recommendations prepared by the chapter author were pre-circulated to the
members. Evidence for this topic was presented and deliberated upon in
1- to 2-day meetings, 2 to 3 times per year from February 1991 to November
1992. Consensus was reached on final recommendations.
Benefits,
Harms, and Costs
Weight alone is not a good measure of obesity. Body-mass index is more
appropriate as is triceps or subscapular skin-fold thickness assessment.
Skin-fold thickness measurements correlate with total body fatness in the
range of 0.7 to 0.8 but are not as accurate in obese children.
No evidence exists that traditional adult interventions of reduced calories
and increased exercise lead to long-term weight loss. One study did show
reductions in weight in 21 children who were from 30% to 144% overweight;
at 4 to 10 years, 10 had maintained some of the weight reductions and 11
had regained all their lost weight plus an additional 5% to 68%. Exercise
can help to maintain an ideal body weight but evidence is mixed about the
role of exercise in weight loss in obese children.
2 cohort studies showed weight reductions in children who received a
program of behaviour modification but at no point did the group fall below
the obesity definition (20% overweight). Evidence is mixed on the role
of parents in weight loss programs for their children. In 1 study children
from intact, predominantly white, middle-class families received diet and
exercise information and behavioural modification for the child alone,
for the child and parent, or only information without behavioural modification.
After 10 years the children in the group who received behavioural modification
for children and parents were less obese than those in the other groups.
Side effects of dietary restrictions include growth and developmental
delays that can become permanent.
Recommendations
Recommendation grade [A, B, C, D, E] and level of evidence
[I, II-1, II-2, II-3, III] are indicated after each recommendation. Citations
in support of individual recommendations are identified in the guideline
text.
-
Insufficient evidence exists to include or exclude, in the PHE of infants
and children, measurement of heights and weights to prevent obesity [C,
II-2]. Measurements should continue for infants
to screen for failure to thrive.
-
Insufficient evidence exists to include or exclude, in the PHE of infants
and children, screening for obesity using skin-fold thickness, body-mass
index, etc. [C, II-2].
-
Fair evidence exists to exclude very low calorie diets from the routine
treatment of preadolescent children who are obese [D,
II-2].
-
Insufficient evidence exists to include or exclude exercise in programs
of initial weight loss or maintenance of weight in children who are obese
[C, II-2].
-
Insufficient evidence exists to include or exclude family-based nutrition
and exercise education and behaviour modification in the routine treatment
of obese children [C,
I]. Some evidence shows that intensive programs can be effective in
highly selected, highly motivated families.
Validation
This report was externally peer reviewed. The American Academy of Pediatrics
recommended that children's height and weight be measured throughout infancy,
annually from ages 1 to 6, and bi-annually thereafter. The 1989 U.S. Preventive
Services Task Force also recommends regular height and weight measurement.
Nutrition and exercise counselling recommendations were not made for children.
Sponsors
The Canadian Task Force on Preventive Health Care
developed this guideline with funding from Health Canada.
Selected
References
Source Document
Link to Full Text of this
review
Link to Summary Table of Recommendations of this review
Link to Selected References list of this review
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