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
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
Logic Framework: Nutrition and Community Health IntermediateOutcomes Modifiable Determinants POPULATION FOOD INTAKE Food Consumption Patterns (e.g. fruits, vegetables) Intake of Nutrients and Food Components: Vitamins Minerals Fiber Fats Other food constituents Dietary supplements Alcohol Energy balance • Food Supply Factors • Agriculture policy • Nutrition policy • Science and technology • Food production, processing, storage and distribution • Food fortification • Food safety Physiologic Indicators: Growth Adipose tissue Musculoskeletal Gastrointestinal Metabolic Cardiovascular Reproductive Immunological Neurological I N T E R V E N T I O N S • Environmental Factors • Food Availability & Price • Neighborhoods • Schools • Worksites • Homes • Local, state & national food assistance programs Community Health Outcomes Life Stage Requirements Pregnancy Lactation Childhood Adolescence Adulthood Older Adulthood • Morbidity • Mortality • Measures of Health & Fitness • Quality of Life • Consumer Demand • Household resources • Nutrition knowledge • Cultural practices • Psychosocial characteristics • Taste and preferences • Advertising and marketing Physical Activity Patterns Genetics, Co-morbidities
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 interventionsimplemented 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.
Study Outcomes School policy Behaviors Dietary intake Physical activity Environmental support for healthy choices Knowledge Nutritional needsFood content Attitudes Self-care Body image Abilities Self-assessment Behavioral change skills Media literacy Physiologic Indicators Normal growth & development Fitness Health status School achievement Multi-component School-based Nutrition Interventions Nutrition & health messages Promotion of self-awareness, self-efficacy
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 30 25 20 15 10 5 0 Healthy Diet Cancer Obesity CVD
Intervention Combinations 4 studies reported policy change
Study Characteristics Intervention DurationnPercent < 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 Percent Immediate 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 studies -1.5 1.0 .5 0 .5 1.0 1.5 Favors Control Favors Treatment
Difference in % kcal from Fat (I-C) -4 -3 -2 -1 0 1 2 3 4 Favors Treatment Favors Control
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 -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.
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 ApproachesSchool-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 Recommend Against (Strong or Sufficient Evidence) Insufficient Evidence Recommend For (Strong or Sufficient Evidence)
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