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Clemson NUTR 2160 - INTERVENTION STUDIES

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INTERVENTION STUDIESINTERVENTIONS – set of activities aimed to bring about change or produce identifiable outcomes. Include: policy, regulatory initiatives, single strategy projects, or multi-component programs.★ INTERVENTION STUDY – ranges from: • Short-term study – immediate effect of intervention measured over minutes to hours or • Long-term study – effect of an intervention over a long period of time TYPES OF INTERVENTION STUDIES ★ • Pilot Study (or Feasibility/Exploratory Study) Implemented on a small scale to: – Assess how realistic it would be to conduct a full-scale study. – Test recruitment procedures in a defined population. – Develop and test research instruments. – Develop and test novel intervention. – Identify logistical challenges in implementing a full-scale study. – Convince funding bodies that such a study is worth funding. – Provide data on distribution/variability and inform power calculations.★ • Randomized controlled trials (RCT) – participants randomized to study groups to increase confidence that changes observed during the study are directly caused by the intervention. ❏ Without a control group, cannot make cause-and-effect statements. – Parallel – each participant receives only one of the interventions. – Cross-over – participants are in 2 groups that receive interventions in a different order. – Factorial Design – all possible combinations of two or more interventions – Cluster Randomized Design – a cluster of individuals are randomized★ • Quasi-experimental studies -- often used in public health but theinternal validity is compromised. – Before-and-after study without a control group – Before-and-after study with a non-equivalent groups design★ Population-based fortification studies – implemented as part of public health policy to correct dietary deficienciesCONSIDERATIONS WHEN PLANNING INTERVENTION STUDIES (look at page)POPULATION-BASED STUDIESEXAMPLES OF POPULATION-BASED METHODOLOGIES:★ Ecological Studies – characterize the diet or nutritional status of a population rather than link individual exposure to health outcomes. ❏ Limitations – individual measures do not represent a group. ❏ Two measures needed: ❖ Dietary intake (exposure of interest) - National food supply (USDA/FAO) – picture of thepattern of a country’s food supply at one point in time. - Household budget surveys – food availability at a household level - Individual survey data – information about individuals.❖ Disease (health outcome) - Routine measures of mortality and morbidity ★ Cross-sectional Studies (sometimes called Prevalence Studies) – observational study that characterizes the theoretical population at one point in time. The prevalence is the rate of a disease in the population at a particular point in time. ❏ Limitations -- exposure and disease measured at same time so cannot conclude which is cause and which is effect. ★ Case-control Studies – people with a disease (cases) compared to people without the disease (controls). Both groups (cases and controls) have past exposure to the dietary factor(s) of interest and compared to estimate therisk of disease associated with the risk factor. ❏ Limitations – dietary measurement error bc of recall bias and need large sample size.★ Prospective Longitudinal Study (Follow-up or Cohort Study) – individuals are followed up over a period of timewhere disease or health outcomes are identified. Subjectsshould be free of the disease being investigated at the start of the study. ❏ Advantages – recall bias prevented, decreased selection bias, can be used to study a wide range of disease and health outcomes, time relationship between exposure and disease can be determined in longitudinal studies. ❏ Disadvantages – time-consuming, expensive, and high rates of attrition.★ NATIONAL NUTRITION MONITORING AND RELATED RESEARCH PROGRAM (NNMRRP) – interconnected federal and state activities aimed to study the relationship between food and health through data collection: • Nutrition and health • Food and nutrient consumptions • Knowledge, attitudes and behavior • Food composition and databases • Food supply★ NUTRITION MONITORING – an ongoing description of nutrition conditions in the population, with particular attention to subgroups to plan, analyze, and predict future trends.★ ACASI – audio computer assisted self interview AMPM-- automated multiple-pass method; CAPI – computer assisted personal interview; MEC – mobile examination component★ LIMITATIONS • Sampling Bias – under or over-represent population groups because of how sample was selected • Non-Sampling Bias – systematic errors related tononresponse, measurement, or data processing • Design Effects • Participation Data – a self-selected population so are not representative of the community • Quality of Data – calibrated equipment, periodic training of staff, and quality control and assurance programs needed.★ OTHER SURVEYS: Food Security – U.S. Household Food Security Survey Module – measures household food insecurity. ❏ Current Population Survey Food Security Supplements – food sufficiency, use of food programs ❏ National Household Food Acquisition and Purchase Survey -- to collect unique and comprehensive data about householdfood purchases and acquisitions. Diet Quality – ❏ Healthy Eating Index (HEI) -- USDA usesthe HEI to monitor the diet quality of the U.S. population and the low-income subpopulation. ❏ Dietary Quality Indexes -- based on 10 dietary recommendations ❏ Risk Factor Surveillance ❏ – Behavioral Risk Factor Surveillance System (BRFSS) – data collected about U.S. residents regarding their health-related risk behaviors❏ Pediatric Nutrition Surveillance System (PedNSS) -- data collected to determine the prevalence and trends of nutrition-related indicators for low-income children in federally-funded programs.❏ National Health Interview Survey (NHIS) -- provide nationally representative estimates on a wide range of health status ❏ The Community Nutrition Mapping Project (CNMap) -- combines food and nutrition indicators. CNMap was created to provide a snapshot of these indicators at the state and national level. CNMap is divided into five major categories: nutrient intakes, healthy eating patterns,physical activity and body weight indicators,


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