Bridging the Evidence Gap in Obesity Prevention A Framework to Inform Decision Making (2010) / Chapter Skim
Currently Skimming:
5 Specifying Questions and Locating Evidence: An Expanded View
5 Specifying Questions and Locating Evidence: An Expanded View
Pages 89-114
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 89... ...
• Specialized research training may be required for the use of certain types of evidence. • The process of locating evidence will reveal evidence gaps and highlight areas in which new evidence needs to be generated.
|
From page 90... ...
The chapter concludes with a discussion of considerations in gathering the evidence. Specif y O Questions pp or tu e ni tiv tie ec s sp Identify and gather the to Locate r Pe G t ypes of evidence that are en Evidence potentially relevant to the s er em questions at st e Sy Ev i de Apply standards of qualit y nc Evaluate e as relevant to different Evidence t ypes of evidence Select and summarize the Assemble relevant evidence according O Evidence to considerations for its use pp or tu e ni tiv tie ec s sp to r Pe G Inform Use evidence in the en s decision-making process Decisions er em at st e Sy Ev i de nc e FIGURE 5-1 The Locate Evidence, Evaluate Evidence, Assemble Evidence, Inform Decisions (L.E.A.D.)
|
From page 91... ...
" This typol ogy is detailed in the following subsections. "Why" Questions Locating evidence guided by "Why" questions helps decision makers characterize the reasons for taking action on a public health issue in their particular region or locale.
|
From page 92... ...
Studies that generate this type of evidence may include sample surveys or com pilations of administrative data for monitoring and surveillance, population trend analysis, or studies of health impact, as well as studies that produce cost estimates and projections of future burden. For example, evidence that provides insight into obesity-related health care costs and lost productivity is helpful for comparing the eco TABLE 5-1 Areas of Concerns and Examples of Evidence Needed: "Why" Questions Area of Concern Examples of Evidence Needed Public health situation • Health burden Recorded levels of illness, disease, or death related to obesity • Frequency/incidence of Number of people or rate of new cases affected by obesity or obesity-related diseases disease or risk factor • Social or environmental Number of catchment areas that do not have a supermarket or food stores offering healthful determinants of disease foods or suitable options for physical activity and exercise or risk factor • Trends Rates of increase of obesity, obesity-related diseases, or adverse social determinants • Health disparities Relative or absolute differences in risk among demographic groups or subgroups Monetary and social costs • Health care costs Estimates of public dollars currently spent on providing health care for obesity or related conditions • Other societal costs Estimates of dollars spent by or lost from the public or private sector due to consequences of obesity (e.g., employee absenteeism)
|
From page 93... ...
To answer "What" questions, decision makers require evidence on the effects or impact of particular interventions on specific health outcomes over the short or long TABLE 5-2 Areas of Concerns and Examples of Evidence Needed: "What" Questions Area of Concern Examples of Evidence Needed Presumed mechanisms of intervention effects in target populations • Intervention theory or logic Underlying assumptions (explicit or implicit) about how the intervention will improve health outcomes • Causal pathways Expected direct or indirect pathways linking the intervention to the outcomes at one or more levels and for different demographic groups • Multiple causal levels for multiple Intervening or interacting influences that might facilitate or hinder the effects in influences groups at risk Effectiveness of intervention based on empirical studies or simulations • Links between intervention delivery Evidence that the intervention leads to the outcomes, including evidence of and outcomes authentic and consistent implementation when effects were obtained • Comparative outcomes Effects of an intervention on the outcome in comparison with other intervention options or no intervention, including evidence on effects in different demographic groups • Sustained effects Evidence that effects of the appropriately implemented intervention are sustained over time • Contextualized effects Evidence of circumstances under which the evidence for effectiveness of the intervention is strongest, including evidence of other factors that influenced or interacted with the intervention (e.g., individual, family, community, or school factors)
|
From page 94... ...
provide a good example of a health impact assessment of a state law. Using published and unpublished data to model consumer response to point-of-purchase calorie postings at large chain restaurants, the authors quantify the potential impact of California's state menu labeling law on population weight gain in Los Angeles County.
|
From page 95... ...
Answers to "How" questions may feed back to "Why" and "What" questions by helping decision makers determine how plans and expectations should be adjusted to their context, what resources are needed to TABLE 5-3 Areas of Concern and Examples of Evidence Needed: "How" Questions Area of Concern Examples of Evidence Needed Relevance of the intervention on a large scale • Generalizability Likelihood of achieving the expected outcomes in different demographic groups and in different communities/regions • Sustainability Likelihood that the intervention effect will last more than 1 to 5 years in the various groups • Stakeholder acceptance Likelihood that the intervention be well received by the target population/community and program delivery personnel Costs and benefits of largescale implementation • Cost-effectiveness Costs of the intervention versus measured effects on the outcomes of interest (e.g., premature deaths averted, years of life saved, pounds lost) compared with other competitive interventions • Cost/benefit Value of health benefits versus the costs of implementation compared with other competitive interventions • Cost feasibility Costs of implementing the intervention on a communitywide scale compared with other competitive interventions • Cost minimization Costs of implementing the intervention in a hospital compared with costs of implementing a competitive intervention in a community clinic and achieving the same outcome • Cost utility Stakeholder preferences versus implementation costs compared with other competitive interventions Political and practical concerns • Implementation priorities Fit of the intervention with community or policy priorities; basis for giving this intervention high priority • Portfolio balance Fit within an overall set of interventions if considerations of feasibility, size of impact, and certainty of effect are combined • Strategic planning Strategies and tactics that can be used to mount this intervention • Potential challenges Implementation challenges that can be anticipated and evidence on how to overcome them Specifying Questions and Locating Evidence: An Expanded View
|
From page 96... ...
For example, the Pathways obesity prevention study in American Indian Children and the HEALTHY study to reduce risk factors for type 2 diabetes were school-based interventions that included extensive, detailed qualitative and quantitative measures to track implementation in addition to measures used to track study outcomes (Schneider et al., 2009; Steckler et al., 2003; Stone et al., 2003)
|
From page 97... ...
BMI measurement and reporting • • Individual BMI reports Subpopulation reports of obesity prevalence • • School and school district reports of obesity prevalence • Statewide report of obesity prevalence • • Pouring contract review disclosure School health index (CDC) in all schools Child Health Advisory Committee • • • Population Interventions Professional education requirements for cafeteria workers • • Vending machine/competitive food restrictions and elimination from • • schools Content requirements for vended/competitive foods • • Physical activity requirements • • • Health education requirements • • • Local/district-level School Nutrition and Physical Activity Advisory • • • Committees Individual Interventions Child health reports to parents • • Continuing medical education on obesity prevention/treatment for health • • professionals Reimbursement plans for treating obesity • • • Surveillance Annual evaluation of Act 1220 programs (UAMS COPH)
|
From page 98... ...
Much of this evidence speaks to various aspects of the obesity prevalence issue, correlates of obesity, and relevant lifestyle factors in a situation-specific manner. This evidence might be collected by using archival data from Bridging the Evidence Gap in Obesity Prevention
|
From page 99... ...
8. What is the parallel evidence on policy actions addressing other community health issues, such as smoking?
|
From page 100... ...
POTENTIALLY USEFUL SOURCES OF EVIDENCE Seven categories of study designs and sources of evidence may be useful for addressing the concerns listed in Tables 5-1 to 5-3: • nonexperimental or observational studies, • experimental and quasi-experimental studies, • qualitative research and analysis, • mixed-method studies, • evidence synthesis methods, • parallel evidence, and • expert knowledge. It is important to note that quality standards apply to all of these categories, and the relative value of each source depends on the decision-making context (see Chapter 6)
|
From page 101... ...
For example, a quasi-natural experimental design was used to estimate the causal impact of physical education classes on overall student physical activity and weight (Cawley et al., 2007) , and an interrupted time series design was used to evaluate the effectiveness of a framework designed to increase fruit and water consumption (Laurence et al., 2007)
|
From page 102... ...
descriptive data on stakeholder preferences A secondary analysis of the correlation or Analysis of Existing Based on the health department's data on a city other measure of risk between levels of Databases population, what were the recorded levels of cardiovascular disease related to obesity in measured obesity and cardiovascular disease in a selected cross-sectional sample 2007? ("Why" question)
|
From page 103... ...
are the groups that are matched on relevant characteristics; other potential influences on intervention outcomes are statistically controlled.) An interrupted time series study tracking changes Using ongoing obesity measures as control data in a group of children, is body mass reduced in obesity outcomes over time when a nutrition when this intervention is administered in program is administered periodically alternating cycles?
|
From page 104... ...
Examples of mixed-method studies include surveys and interviews combined with RCTs, interviews combined with interrupted time series analysis, policy-related content analysis combined with focus group interviews, health impact analysis using archival databases and surveys, economic analysis using archival databases and sur veys, systems mapping based on a review of the literature, simulation studies, and mixed-method evidence synthesis techniques (discussed in the next section)
|
From page 105... ...
A content analysis of food logs, menus, and meal Qualitative Analysis Is there qualitative evidence to show that an plans combined with an interrupted time series Combined with intervention was implemented as intended study tracking changes in obesity outcomes Quasi-experimental when outcomes improved in a time series Study analysis? How consistently and authentically when a nutrition program is implemented was the intervention implemented when periodically effects were obtained?
|
From page 106... ...
A meta-analysis to estimate the average effect on Meta-analyses: Based on meta-analysis of effects from Experimental and/or experimental or quasi-experimental research, childhood obesity levels found in eligible studies Quasi-experimental what is the evidence on the effectiveness of of mandatory school exercise programs Studies this intervention? ("What" question)
|
From page 107... ...
. Syntheses of Qualitative Research Despite some initial controversy, a place for the inclusion of qualitative research in systematic reviews and evidence syntheses was established in medicine in 2001 in an editorial in the British Medical Journal (Dixon-Woods and Fitzpatrick, 2001)
|
From page 108... ...
The authors then proceeded with the evidence synthesis, summarizing effects found across studies by group. Their conclusions showed that while nutrition education, skills training, and physical education were not effective in controlling childhood obesity, compulsory rather than voluntary physical activity was.
|
From page 109... ...
Consensus views are sometimes based on systematic reviews or other forms of evidence synthesis but still require interpretation or judgment about the evidence that is collected, and may require drawing conclusions in the absence of any or enough relevant evidence. Expert consensus and expert opinion should be appraised based on the credentials and experience of the experts involved, supporting documentation, the transparency and rigor of the consensus process, and ruling out of any conflicts TABLE 5-9 Types of Parallel Evidence and Examples of Their Uses Type of Evidence Questions That Can Be Addressed Specific Applications Intervention impact or effectiveness studies Research Evidence Given the existing evidence on the effectiveness of on Effects of Parallel tobacco and alcohol taxes, would soda taxes be showing that strategies to influence public Interventions similarly effective in reducing obesity on a large behaviors work scale?
|
From page 110... ...
Examples of this type of evidence include national committee reports based on delib erative processes; guidelines from national associations, health foundations, and com mitted practitioners or health professional organizations; and other expert statements. Table 5-10 provides examples of this type of evidence and how it might be used.
|
From page 111... ...
Evidence gaps will be identified in this process and in some cases may predominate. That is, the available evidence -- even when broadly sought -- may not address decision makers' questions because no studies relevant to the issue or to the potential setting have been done, or because important studies do not report key details needed to fully interpret and apply the results from a practical perspective.
|
From page 112... ...
2001. Qualitative research in systematic reviews.
|
From page 113... ...
2003. Pathways process evaluation results: A school-based preven tion trial to promote healthful diet and physical activity in American Indian third, fourth, and fifth grade students.
|
From page 114... ...
2004. Integrating qualitative research with trials in systematic reviews.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.