Nutrition & Physical Activity Intervention Effectiveness

Systematic Reviews & Evidence-Based Recommendations

Laurie M. Anderson, PhD, MPH

Centers for Disease Control & Prevention

Why Systematic Reviews for Evidence Synthesis?

Explosive growth of scientific information too much to keep up with contradictory results

The body of intervention literature can be quite large, inconsistent, and uneven in quality

Systematic reviews for research synthesis

Combine many studies with different methods and results

Look for consistencies in set of findings More robust than single study May pinpoint why studies differ Shows what is effective and why

Task Force on Community Preventive Services

Independent Task Force

Goal - to provide a comprehensive set of evidence-based recommendations on the effectiveness and feasibility of health promotion & disease prevention interventions in community settings

Community Guide Task Force

Jonathan Fielding, Chair Public Health Los Angeles Co, UCLA

Barbara Rimer, Vice Chair University North Carolina Chapel Hill

Noreen Clark University Michigan School of Public Health

John Clymer Partnership for Prevention

Kay Dickersin US Cochrane Center, Brown University

Alan Hinman Task Force on Child Survival

Robert Johnson New Jersey Medical School

Garland Land Missouri Department of Health

Patricia Noland Rhode Island Department of Health

Alonzo Plough Seattle King County Department of Health

Nico Pronk HealthPartners

Dennis Richling Midwest Business Group on Health

Steven Teutsch Merck & Company

Task Force Priority Topics

Environmental Influences Social Environment

Risk Behaviors Specific Conditions Tobacco Use Alcohol Abuse/Misuse Other Substance Abuse Poor Nutrition Inadequate Physical Activity Unhealthy Sexual Behaviors

Vaccine-Preventable Diseases Pregnancy Outcomes Violence Motor Vehicle Occupant Injuries Depression Cancer Diabetes Oral Health

Steps in Conducting a Review

Multidisciplinary team of experts Develop conceptual framework Prioritize intervention topics State precise purpose of the review Search for and retrieve evidence Rate quality of evidence Summarize evidence Translate into a recommendation

Evidence Of ….

Program effectiveness Feasibility of implementation Acceptability to the population Unanticipated harms (or benefits) Cost-effectiveness

Consumer Demand•Household resources•Nutrition knowledge •Cultural practices •Psychosocial characteristics •Taste and preferences•Advertising and marketing

Logic Framework: Nutrition and Community Health

Modifiable Determinants

Food Supply Factors•Agriculture policy

•Nutrition policy

•Science and technology

•Food production, processing, storage and distribution

•Food fortification

•Food safety

Environmental Factors•Food Availability & Price

•Neighborhoods

•Schools•Worksites

•Homes

•Local, state & national food assistance programs

POPULATION FOOD INTAKE

Food Consumption Patterns (e.g. fruits, vegetables)

Intake of Nutrients and Food Components:

VitaminsMinerals

FiberFats

Other food constituentsDietary supplements

AlcoholEnergy balance

Life StageRequirements

Pregnancy Lactation Childhood

AdolescenceAdulthood

Older Adulthood

Intermediate Outcomes

Community Health

Outcomes

Physiologic Indicators:

GrowthAdipose tissue

MusculoskeletalGastrointestinal

MetabolicCardiovascularReproductive

ImmunologicalNeurological

Genetics,Co-morbidities

• Morbidity

• Mortality• Measures of Health & Fitness

• Quality of Life

PhysicalActivityPatterns

I

N

T

E

R

V

E

N

T

I

O

N

S

Priority Ranked Topics for Nutrition

Food & beverage availability in schools.

Comprehensive community approaches to increase fruit & vegetable intake.

Food and beverage advertising to children.

Food & beverage availability, price, portion size, and labeling in restaurants.

Food choice and nutrition education in food assistance programs.

Nutrition and weight management counseling in healthcare settings.

Breast-feeding.

Product labeling in grocery stores, restaurants and vending machines.

Food & beverage availability and price in worksites.

Use of dietary supplements across the lifespan.

Nutrition Topic Review 

Question:

Do multi-component, school-based interventions improve nutrition-related

behaviors and nutritional status of children and adolescents.

Definition:

 School-based nutrition interventions implemented in K-12th grades to promote healthy nutritional attitudes, knowledge and behavior, including eating and physical activity.

The interventions are multi-component and may target food policy, environmental factors and/or nutrition education. Interventions may be directed at school administrators, food service staff, teachers or parents or delivered by special program instructors directly to students.

Environmentalsupport for

healthy choices

Nutrition & health

messages

Promotion ofself-awareness,

self-efficacy

Multi-component

School-based

NutritionIntervention

s

Physiologic Indicators

Normal growth & development Fitness

Health status

Schoolachievement

School policy

Behaviors Dietary intake Physical activity

Knowledge Nutritional needsFood content

Attitudes Self-care Body image

Abilities Self-assessment Behavioral

change skills Media literacy

Study Outcomes

Literature Search Results 1980–2003, publications, dissertations,

government reports, US & non-US

1500 abstracts, ~150 papers, 76 studies

Dual abstraction completed on 76 studies

13 studies did not meet inclusion criteria

14 studies excluded due to limitations in quality

6 studies excluded due to least suitable design

45 reports of 41 studies

Study Aims

Purpose of school intervention program N=41

0

5

10

15

20

25

30

CVD Healthy Diet Cancer Obesity

Intervention CombinationsTotal

Number Curriculum Behavioral Healthy

Food ChoiceEnvironment

Physical Activity

12 x x x

10 x x

9 x

5 x x x

4 x x

4 studies reported policy change

Study Characteristics

Intervention Duration n Percent< 3 months 14 27%

4 to 9 months 10 22%

10 to 24 months 10 22%

25 to 36 months 9 21%

60 months 2 4%

Not reported 2 4%

Total 45

Follow-up Period for Outcome Evaluation

n PercentImmediate 24 55%

1 month 7 16%

2-3 months 3 7%

6-12 months 6 13%

24 months 3 7%

48 months 1 2%

Not reported 1 2%

Total 45

Behavioral Outcomes

Intake of fruit and vegetables

Intake of fat

Intake of saturated fat

Difference in Fruit & VegetableServings per day (I-C)

9 studiesStudy Total N

Mean Difference

Resnicow 1992 1209 0.13

Nicklas 1998 1882 0.4

Perry 1998 407 0.58

Gortmaker 1999 (f) 564 0.4

Gortmaker 1999 (m) 593 0.3

Reynolds 2000 1698 0.89

Friel 2001 187 0.06

Birnbaum 2002 3503 0.13

Baranowski 2003 1489 0.85

Pooled Effect 11532 0.4

-1.5 1.0 .5 0 .5 1.0 1.5

Favors Control Favors Treatment

Difference in % kcal from Fat (I-C)

Study Total NMean

Difference

Walter 1988 235 -2.7

Ellison 1990 (f) 260 -2.7

Ellison 1990 (m) 207 -0.7

Vandongen 1995 (f) 446 -0.34

Vandongen 1995 (m) 423 0.48

Perry 1998 407 -1.81

Gortmaker 1999 (f) 567 -0.67

Gortmaker 1999 (m) 592 -0.31

Gortmaker 1999b 336 -1.44

Nader 1999 5015 -0.9

Reynolds 2000 1698 -1.79

Pooled Effect 10186 -1.17

-4 -3 -2 -1 0 1 2 3 4

Favors Treatment Favors Control

Study Total NMean

Difference

Ellison 1990 (f) 207 -2.3

Ellison 1990 (m) 260 -2.2

Lytle 1996 1182 -0.9

Perry 1998 407 -0.59

Gortmaker 1999b 336 -0.6

Nader 1999 5015 -0.5

Reynolds 2000 1698 -0.74

Pooled Effect 9105 -1.12

Difference in % kcal from Saturated Fat (I-C)6 studies

-3 -2 -1 0 1 2 3

Favors Treatment Favors Control

Difference in % kcal from Saturated Fat (I-C)RCTs

Study Total NMean

Difference

Lytle 1996 1182 -0.9

Perry 1998 407 -0.59

Nader 1999 5015 -0.5

Reynolds 2000 1698 -0.74

Pooled Effect 8302 -0.71

-1.5 -1.0 -.5 0 .5 1.0 1.5

Favors Treatment Favors Control

Meaningful Effects

Is there an effect?Is the effect real?

Findings are based on self-report of dietary intake

Reporting bias may account for some of the effect, possibly rendering small effects negligible

Physiologic & Health Effects

BMI (n=11) Boys -2.7% Girls -0.3% Overall 0%

Skinfold thickness (n=8) Boys 4.3% Girls -5.4% Overall 0%

Systolic B/P (n=10) Overall 0.3%

Serum cholesterol (n=11) Overall -3%

Median Effect Size % Δ I - % Δ C

School Review Conclusions

Number of studies: Sufficient

Magnitude of reported effect was small Fruit & vegetable servings per day: +0.24 Saturated fat as % kcal: –0.71 % point

Consistent? Yes

Biased? Likely

Task Force Recommendation The Task Force found insufficient evidence

to determine whether multicomponent school-based nutrition interventions are effective in increasing fruit and vegetable intake and decreasing fat and saturated fat intake among school-age children.

Evidence was limited because bias due to self-report of dietary intake could not be ruled out.

Guide to Community Preventive Services

Physical Activity Reviews

Informational Approaches

Community-wide campaigns• Large-scale, high intensity, high visibility• Use of TV, radio, newspaper, information

sites• Multi-component, multi-site • ‘Combined Package’

• Recommended

Informational Approaches

Single Component Mass Media • Knowledge, attitudes, and beliefs, behavior• Paid advertisements and donated promotion• TV, radio, newspapers, billboards

Insufficient evidence of effectiveness.

Informational Approaches

“Point-of-decision” prompts • Motivational signs placed by elevators and escalators• Encourage stair use for health/weight control • Single component

Recommended

Behavioral & Social Approaches

School-based

Modified physical education

Health education

TV/video game turn off

College health education

School-based Approaches

Modified Physical Education • Modified curricula and policies• Studies designed to modify the

amount of physical activity during PE• Lifetime activities and games

Recommended

Insufficient Evidence

Health education TV/video game turn off College health education

Behavioral and social approaches

• Individually-adapted health behavior change

• Family-based social support

• Other social support

Behavioral & Social Approaches

Individually Adapted Health Behavior Change

• Goal setting and self-monitoring• Building social support• Behavioral reinforcement• Structured problem solving• Relapse prevention

Recommended

Behavioral & Social Approaches

Social Support in Community Contexts • Creating, strengthening, and maintaining

social networks• Use of ‘buddy’ systems• Contracting• Walking groups

Recommended

Insufficient Evidence

Family-based social support

Environmental and Policy Approaches

Create or enhance access Urban planning – zoning, land use Transportation and infrastructure

Environmental & Policy Approaches

Creation or Enhanced Access to Places for Physical Activity

•Built environment - trails and/or facilities access•Reducing barriers - safety, affordability•Site-specific programs

Recommended

Environmental & Policy Approaches

Street-scale Urban Design and Land Use that Supports Physical Activity in Small Geographic Areas - generally limited to a few blocks

• Improved lighting• Ease and safety of street crossing • Sidewalk continuity• Presence of traffic calming structures• Making aesthetic enhancements

Recommended

Environmental & Policy Approaches

Transportation policies and practices that encourage and facilitate walking and bicycling for transportation

• Policy measures such as roadway design standards

• Expanding public transportation services

• Subsidizing public transportation

• Providing bicycle lanes and racks

• Increasing the cost of parking

Insufficient evidence

Task Force RecommendationStatement

RecommendFor

(Strong orSufficient Evidence)

RecommendAgainst

(Strong orSufficient Evidence)

InsufficientEvidence

Lack of Persuasive Evidence

Lack of evidence does not mean that interventions don’t work

Interventions for which evidence is insufficient should be more thoroughly researched

Interventions that either produce no effect or produce harm(s) should not be used

Research Issues:Nutrition & Physical Activity Reviews

•Much more information about determinants than solutions

•Common outcomes measures

•Measurement Error – intake & physical activity

•Limited duration of intervention studies

•Longer term follow-up measurement

www.TheCommunityGuide.org