Practice-Based Evidence in Community Guide Systematic Reviews.

OBJECTIVES: To assess the relative contributions and quality of practice-based evidence (PBE) and research-based evidence (RBE) in The Guide to Community Preventive Services (The Community Guide). METHODS: We developed operational definitions for PBE and RBE in which the main distinguishing feature was whether allocation of participants to intervention and comparison conditions was under the control of researchers (RBE) or not (PBE). We conceptualized a continuum between RBE and PBE. We then categorized 3656 studies in 202 reviews completed since The Community Guide began in 1996. RESULTS: Fifty-four percent of studies were PBE and 46% RBE. Community-based and policy reviews had more PBE. Health care system and programmatic reviews had more RBE. The majority of both PBE and RBE studies were of high quality according to Community Guide scoring methods. CONCLUSIONS: The inclusion of substantial PBE in Community Guide reviews suggests that evidence of adequate rigor to inform practice is being produced. This should increase stakeholders' confidence that The Community Guide provides recommendations with real-world relevance. Limitations in some PBE studies suggest a need for strengthening practice-relevant designs and external validity reporting standards.

Guiding the way to public health improvement: exploring the connections between The Community Guide's Evidence-Based Interventions and health department accreditation standards.

CONTEXT: Recent years have seen rising interest in initiatives that focus on public health improvement. This includes support for accreditation of public health departments-administered by the Public Health Accreditation Board (PHAB)-and increasing expectations that health departments should use evidence-based programs, services, and policies (interventions) such as those described in The Guide to Community Preventive Services (The Community Guide). OBJECTIVE: This project was initiated to explore the potential connections between Community Guide interventions and PHAB domains, standards, and measures. DESIGN: The project team focused on developing a Crosswalk tool to assist health departments in identifying evidence-based interventions from The Community Guide whose implementation could help document conformity with PHAB domains, standards, and measures. All Community Preventive Services Task Force-recommended interventions were reviewed to determine whether they reflect the intent and requirements of the PHAB standards and measures. MAIN OUTCOME MEASURES: Three types of connections were defined through which Community Guide interventions could be relevant to the required documentation for a PHAB measure. All instances of these connections were identified and included in the Crosswalk. RESULTS: The Crosswalk tool consists of 2 tables. The first table cross-references individual PHAB domains, standards, and measures with interventions from The Community Guide that could help provide documentation for accreditation. The second table can help accreditation preparation staff to engage with program staff. It is searchable by Community Guide topic, identifying the PHAB measures that relate to each Community Guide intervention within that topic. The type, location, and extent of connections between Community Guide interventions and PHAB domains, standards, and measures are presented and discussed. CONCLUSIONS: Tools such as the Crosswalk can be instrumental in advancing the use of evidence-based interventions in public health practice.

Seeking best practices: a conceptual framework for planning and improving evidence-based practices.

How can we encourage ongoing development, refinement, and evaluation of practices to identify and build an evidence base for best practices? On the basis of a review of the literature and expert input, we worked iteratively to create a framework with 2 interrelated components. The first - public health impact - consists of 5 elements: effectiveness, reach, feasibility, sustainability, and transferability. The second - quality of evidence - consists of 4 levels, ranging from weak to rigorous. At the intersection of public health impact and quality of evidence, a continuum of evidence-based practice emerges, representing the ongoing development of knowledge across 4 stages: emerging, promising, leading, and best. This conceptual framework brings together important aspects of impact and quality to provide a common lexicon and criteria for assessing and strengthening public health practice. We hope this work will invite and advance dialogue among public health practitioners and decision makers to build and strengthen a diverse evidence base for public health programs and strategies.

A Community Guide Systematic Review: School Dietary and Physical Activity Interventions.

CONTEXT: Schools can play an important role in supporting a healthy lifestyle by offering nutritious foods and beverages and providing opportunities for physical activity. A healthy diet and regular physical activity may reduce the risk of obesity. This manuscript reports on a Community Guide systematic review examining the effectiveness of interventions in schools combining school meal or fruit and vegetable snack programs and physical activity. EVIDENCE ACQUISITION: Studies meeting the intervention definition were identified from a literature search (search period: January 1990-November 2019). Community Guide systematic review methods were used to assess effectiveness as measured by dietary behavior, physical activity, and weight changes; analyses were conducted in 2020. EVIDENCE SYNTHESIS: Interventions (n=24 studies) were considered effective for increasing physical activity (median increase=21.8 minutes/day; interquartile interval= -0.8 to 27.4 minutes/day), modestly increasing fruit and vegetable intake (median relative increase=12.1%; interquartile interval= -4.6%, 73.4%), and decreasing the prevalence of overweight and obesity (median decrease=2.5 percentage points; interquartile interval= -8.1, -1.6 percentage points) among elementary school students through sixth grade. There were not enough studies to determine the effectiveness of interventions for middle- and high-school students. CONCLUSIONS: School meal or fruit and vegetable snack interventions combined with physical activity were effective in increasing physical activity, with modest effects for improving fruit and vegetable consumption and reducing the prevalence of overweight and obesity among elementary students. These results may inform researchers and school administrators about healthy eating and physical activity interventions.

Community Health Workers to Increase Cancer Screening: 3 Community Guide Systematic Reviews.

INTRODUCTION: Many in the U.S. are not up to date with cancer screening. This systematic review examined the effectiveness of interventions engaging community health workers to increase breast, cervical, and colorectal cancer screening. METHODS: Authors identified relevant publications from previous Community Guide systematic reviews of interventions to increase cancer screening (1966 through 2013) and from an update search (January 2014-November 2021). Studies written in English and published in peer-reviewed journals were included if they assessed interventions implemented in high-income countries; reported screening for breast, cervical, or colorectal cancer; and engaged community health workers to implement part or all of the interventions. Community health workers needed to come from or have close knowledge of the intervention community. RESULTS: The review included 76 studies. Interventions engaging community health workers increased screening use for breast (median increase=11.5 percentage points, interquartile interval=5.5‒23.5), cervical (median increase=12.8 percentage points, interquartile interval=6.4‒21.0), and colorectal cancers (median increase=10.5 percentage points, interquartile interval=4.5‒17.5). Interventions were effective whether community health workers worked alone or as part of a team. Interventions increased cancer screening independent of race or ethnicity, income, or insurance status. DISCUSSION: Interventions engaging community health workers are recommended by the Community Preventive Services Task Force to increase cancer screening. These interventions are typically implemented in communities where people are underserved to improve health and can enhance health equity. Further training and financial support for community health workers should be considered to increase cancer screening uptake.

Navigating the road ahead: public health challenges and the interactive systems framework for dissemination and implementation.

Public health is currently faced with an array of critical challenges and disconnects. Research and evaluation have identified a number of evidence-based strategies for effecting behavior change at individual, group, organizational, and environmental levels, all of which hold promise for leading to substantial reductions in morbidity and mortality, and increased quality of life. Unfortunately, there is huge variability across the public health system in awareness of the value of using evidence to inform decision making, let alone in capacity to locate, assess, compare, select, justify, adapt, implement, and evaluate evidence-based strategies, or to participate in building the evidence base for practice-based innovations. As a result, many communities may not be benefitting from research-tested and practice-based strategies that could help them to meet their public health goals more efficiently and effectively. CDC's Interactive Systems Framework for Dissemination and Implementation (ISF), released in 2008, was designed to help close this gap between research and practice. This commentary identifies the ways in which the ISF framework is useful in addressing the research practice gap; revisits the elements of the framework that have continued to guide research and practice in fruitful ways; and highlights areas that need further development to meet current public health challenges.

Intimate Partner and Sexual Violence Prevention Among Youth: A Community Guide Systematic Review.

INTRODUCTION: Intimate partner violence and sexual violence are widespread and often occur early in life. This systematic review examines the effectiveness of interventions for primary prevention of intimate partner violence and sexual violence among youth. METHODS: Studies were identified from 2 previous systematic reviews and an updated search (January 2012-June 2016). Included studies were implemented among youth, conducted in high-income countries, and aimed to prevent or reduce the perpetration of intimate partner violence or sexual violence. In 2016-2017, Guide to Community Preventive Services (Community Guide) methods were used to assess effectiveness as determined by perpetration, victimization, or bystander action. When heterogeneity of outcomes prevented usual Community Guide methods, the team systematically applied criteria for favorability (statistically significant at p<0.05 or approaching significance at p<0.10) and consistency (75% of results in the same direction). RESULTS: A total of 28 studies (32 arms) met inclusion and quality of execution criteria. Interventions used combinations of teaching healthy relationship skills, promoting social norms to protect against violence, or creating protective environments. Overall, 18 of 24 study arms reported favorable results on the basis of the direction of effect for decreasing perpetration; however, favorability for bystander action diminished with longer follow-up. Interventions did not demonstrate consistent results for decreasing victimization. A bridge search conducted during Fall 2020 confirmed these results. DISCUSSION: Interventions for the primary prevention of intimate partner violence and sexual violence are effective in reducing perpetration. Increasing bystander action may require additional follow-up as effectiveness diminishes over time. Findings may inform researchers, school personnel, public health, and other decision makers about effective strategies to prevent intimate partner violence and sexual violence among youth.

Sources of Support for Studies That Inform Recommendations of the Community Preventive Services Task Force.

OBJECTIVES: The Community Preventive Services Task Force (CPSTF) makes evidence-based recommendations about preventive services, programs, and policies in community settings to improve public health. CPSTF recommendations are based on systematic evidence reviews. This study examined the sponsors (ie, sources of financial, material, or intellectual support) for publications included in systematic reviews used by the CPSTF to make recommendations during a 9-year period. METHODS: We examined systematic evidence reviews (effectiveness reviews and economic reviews) for CPSTF findings issued from January 1, 2010, through December 31, 2018. We assessed study publications used in these reviews for sources of support; we classified sources as government, nonprofit, industry, or no identified support. We also identified country of origin for each sponsor and the most frequently mentioned sponsors. RESULTS: The CPSTF issued findings based on 144 systematic reviews (106 effectiveness reviews and 38 economic reviews). These reviews included 3846 publications: 3363 publications in effectiveness reviews and 483 publications in economic reviews. Government agencies supported 57.1% (n = 1919) of publications in effectiveness reviews and 59.2% (n = 286) in economic reviews. More than 1500 study sponsors from 36 countries provided support. The National Institutes of Health was the leading sponsor for effectiveness reviews (21.3%; 718 of 3363) and economic reviews (16.2%; 78 of 480), followed by the Centers for Disease Control and Prevention (7.0%; 234 of 3363 effectiveness reviews and 14.8%; 71 of 480 economic reviews). CONCLUSIONS: The evidence base used by the CPSTF was supported by an array of sponsors, with government agencies providing the most support. Study findings highlight the need for sponsorship transparency and the role of government as a leading supporter of studies that underpin CPSTF recommendations for improving public health.

Healthier Food and Beverage Interventions in Schools: Four Community Guide Systematic Reviews.

CONTEXT: Healthy eating during childhood is important for optimal growth and helps reduce the risk of obesity, which has potentially serious health consequences. Changing the school food environment may offer one way to improve students' dietary intake. This manuscript reports 4 Community Guide systematic reviews examining the effectiveness of interventions in schools promoting healthy eating and weight. EVIDENCE ACQUISITION: School obesity prevention programs aiming to improve diet were identified from a 2013 Agency for Health Care Research and Quality systematic review and an updated search (August 2012-January 4, 2017). In 2017-2018, Community Guide systematic review methods were used to assess effectiveness as determined by dietary behavior and weight changes. EVIDENCE SYNTHESIS: Interventions improving school meals or offering fruits and vegetables (n=27 studies) are considered effective. Evidence is insufficient to determine the effectiveness of interventions supporting healthier snack foods and beverages outside of school meal programs given inconsistent findings (n=13 studies). Multicomponent interventions to increase availability of healthier foods and beverages are considered effective. These interventions must include 1 component from school meals or fruit and vegetable programs and interventions supporting healthier snack foods and beverages (n=12 studies). There is insufficient evidence to determine the effectiveness of interventions to increase water access because only 2 studies met inclusion criteria. CONCLUSIONS: A total of 2 school-based dietary interventions have favorable effects for improving dietary habits and modest effects for improving or maintaining weight. More evidence is needed regarding interventions with insufficient findings. These reviews may inform researchers and school administrators about healthy eating and obesity prevention interventions.

The scientific basis for law as a public health tool.

Systematic reviews are generating valuable scientific knowledge about the impact of public health laws, but this knowledge is not readily accessible to policy makers. We identified 65 systematic reviews of studies on the effectiveness of 52 public health laws: 27 of those laws were found effective, 23 had insufficient evidence to judge effectiveness, 1 was harmful, and 1 was found to be ineffective. This is a valuable, scientific foundation-that uses the highest relevant standard of evidence-for the role of law as a public health tool. Additional primary studies and systematic reviews are needed to address significant gaps in knowledge about the laws' public health impact, as are energetic, sustained initiatives to make the findings available to public policy makers.

Economics of Multicomponent Interventions to Increase Breast, Cervical, and Colorectal Cancer Screening: A Community Guide Systematic Review.

CONTEXT: The Community Preventive Services Task Force recently recommended multicomponent interventions to increase breast, cervical, and colorectal cancer screening based on strong evidence of effectiveness. This systematic review examines the economic evidence to guide decisions on the implementation of these interventions. EVIDENCE ACQUISITION: A systematic literature search for economic evidence was performed from January 2004 to January 2018. All monetary values were reported in 2016 US dollars, and the analysis was completed in 2018. EVIDENCE SYNTHESIS: Fifty-three studies were included in the body of evidence from a literature search yield of 8,568 total articles. For multicomponent interventions to increase breast cancer screening, the median intervention cost per participant was $26.69 (interquartile interval [IQI]=$3.25, $113.72), and the median incremental cost per additional woman screened was $147.64 (IQI=$32.92, $924.98). For cervical cancer screening, the median costs per participant and per additional woman screened were $159.80 (IQI=$117.62, $214.73) and $159.49 (IQI=$64.74, $331.46), respectively. Two studies reported incremental cost per quality-adjusted life year gained of $748 and $33,433. For colorectal cancer screening, the median costs per participant and per additional person screened were $36.63 (IQI=$7.70, $139.23) and $582.44 (IQI=$91.10, $1,452.12), respectively. Two studies indicated a decline in incremental cost per quality-adjusted life year gained of $1,651 and $3,817. CONCLUSIONS: Multicomponent interventions to increase cervical and colorectal cancer screening were cost effective based on a very conservative threshold. Additionally, multicomponent interventions for colorectal cancer screening demonstrated net cost savings. Cost effectiveness for multicomponent interventions to increase breast cancer screening could not be determined owing to the lack of studies reporting incremental cost per quality-adjusted life year gained. Future studies estimating this outcome could assist implementers with decision making.

Study designs for effectiveness and translation research :identifying trade-offs.

BACKGROUND: Practitioners and policymakers need credible evidence of effectiveness to justify allocating resources to complex, expensive health programs. Investigators, however, face challenges in designing sound effectiveness and translation research with relevance for "real-world" settings. METHODS: Research experts and federal and foundation funders (n= approximately 120) prepared for and participated in a symposium, held May 4-5, 2004, to weigh the strengths, limitations, and trade-offs between alternate designs for studying the effectiveness and translation of complex, multilevel health interventions. RESULTS: Symposium attendees acknowledged that research phases (hypothesis generating, efficacy, effectiveness, translation) are iterative and cyclical, not linear, since research in advanced phases may reveal unanswered questions in earlier phases. Research questions thus always need to drive the choice of study design. When randomization and experimental control are feasible, participants noted that the randomized controlled trial with individual random assignment remains the gold standard for safeguarding internal validity. Attendees highlighted trade-offs of randomized controlled trial variants, quasi-experimental designs, and natural experiments for use when randomization or experimental control or both are impossible or inadequately address external validity. Participants discussed enhancements to all designs to increase confidence in causal inference while accommodating greater external validity. Since no single study can establish causality, participants encouraged replication of studies and triangulation using different study designs. Participants also recommended participatory research approaches for building population relevance, acceptability, and usefulness. CONCLUSIONS: Consideration of the study design choices, trade-offs, and enhancements discussed here can guide the design, funding, completion, and publication of appropriate policy- and practice-oriented effectiveness and translational research for complex, multilevel health interventions.

Community Guide Cardiovascular Disease Economic Reviews: Tailoring Methods to Ensure Utility of Findings.

The Community Preventive Services Task Force recommended five interventions for cardiovascular disease prevention between 2012 and 2015. Systematic economic reviews of these interventions faced challenges that made it difficult to generate meaningful policy and programmatic conclusions. This paper describes the methods used to assess, synthesize, and evaluate the economic evidence to generate reliable and useful economic conclusions and address the comparability of economic findings across interventions. Specifically, steps were taken to assess completeness of data and identify the components and drivers of cost and benefit. Except for the intervention cost of self-measured blood pressure monitoring intervention, either alone or with patient support, all cost and benefit estimates were standardized as per patient per year. When possible, intermediate outcomes were converted to quality-adjusted life year. Differences within and between interventions were considered to generate economic conclusions and inform their comparability. The literature search period varied among interventions. This analysis was completed in 2016. Although team-based care, self-measured blood pressure monitoring with patient support, and self-measured blood pressure monitoring within team-based care were found to be cost effective, their cost-effectiveness estimates were not comparable because of differences in the intervention characteristics. Lack of enough data or incomplete information made it difficult to reach an overall economic finding for the other interventions. The Community Guide methods discussed here may help others conducting systematic economic reviews of public health interventions to respond to challenges with the synthesis of evidence and provide useful findings for public health decision makers.

Reducing Recreational Sedentary Screen Time: A Community Guide Systematic Review.

CONTEXT: Sedentary time spent with screen media is associated with obesity among children and adults. Obesity has potentially serious health consequences, such as heart disease and diabetes. This Community Guide systematic review examined the effectiveness and economic efficiency of behavioral interventions aimed at reducing recreational (i.e., neither school- nor work-related) sedentary screen time, as measured by screen time, physical activity, diet, and weight-related outcomes. EVIDENCE ACQUISITION: For this review, an earlier ("original") review (search period, 1966 through July 2007) was combined with updated evidence (search period, April 2007 through June 2013) to assess effectiveness of behavioral interventions aimed at reducing recreational sedentary screen time. Existing Community Guide systematic review methods were used. Analyses were conducted in 2013-2014. EVIDENCE SYNTHESIS: The review included 49 studies. Two types of behavioral interventions were evaluated that either (1) focus on reducing recreational sedentary screen time only (12 studies); or (2) focus equally on reducing recreational sedentary screen time and improving physical activity or diet (37 studies). Most studies targeted children aged ≤13 years. Children's composite screen time (TV viewing plus other forms of recreational sedentary screen time) decreased 26.4 (interquartile interval= -74.4, -12.0) minutes/day and obesity prevalence decreased 2.3 (interquartile interval= -4.5, -1.2) percentage points versus a comparison group. Improvements in physical activity and diet were reported. Three study arms among adults found composite screen time decreased by 130.2 minutes/day. CONCLUSIONS: Among children, these interventions demonstrated reduced screen time, increased physical activity, and improved diet- and weight-related outcomes. More research is needed among adolescents and adults.

Complex interventions and their implications for systematic reviews: A pragmatic approach.

Complex interventions present unique challenges for systematic reviews. Current debates tend to center around describing complexity, rather than providing guidance on what to do about it. At a series of meetings during 2009-2012, we met to review the challenges and practical steps reviewer could take to incorporate a complexity perspective into systematic reviews. Based on this, we outline a pragmatic approach to dealing with complexity, beginning, as for any review, with clearly defining the research question(s). We argue that reviews of complex interventions can themselves be simple or complex, depending on the question to be answered. In systematic reviews and evaluations of complex interventions, it will be helpful to start by identifying the sources of complexity, then mapping aspects of complexity in the intervention onto the appropriate sources of evidence (such as specific types of quantitative or qualitative study). Although we focus on systematic reviews, the general approach is also applicable to primary research that is aimed at evaluating complex interventions. Although the examples are drawn from health care, the approach may also be applied to other sectors (e.g., social policy or international development). We end by concluding that systematic reviews should follow the principle of Occam's razor: explanations should be as complex as they need to be and no more.

Possible lessons from the tobacco experience for obesity control.

Although obesity is increasing to epidemic proportions in many developed countries, some of these same countries are reporting substantial reductions in tobacco use. Unlike tobacco, food and physical activity are essential to life. Yet similar psychological, social, and environmental factors as well as advertising pressures influence the usage patterns of all 3. These similarities suggest that there may be commonalities between factors involved in controlling obesity and tobacco. This review, therefore, seeks to draw lessons from the tobacco experience for the organization of more successful obesity control. Smoking cessation counseling by physicians has been found to be one of the most clinically effective and cost-effective of all disease prevention interventions. When used alone, however, it cannot decrease the cultural acceptability of tobacco and the pressures and cues to smoke. Research and evaluation have shown the key elements of tobacco control to be (1) clinical intervention and management, (2) educational strategies, (3) regulatory efforts, (4) economic approaches, and (5) the combination of all of these into comprehensive programs that address multiple facets of the environment simultaneously. For each element, we present the evidence outlining its importance for tobacco control, discuss its application to date in obesity control, and suggest areas for further research. Viewing all of the elements involved and recognizing their synergistic effects draws researchers and practitioners back from an exclusive concentration on their particular setting to consider how they might seek to influence other settings in which individuals and populations must negotiate desired changes in nutrition and physical activity.

Participatory research and evaluation: from best practices for all states to achievable practices within each state in the context of the Master Settlement Agreement.

Because the Centers for Disease Control and Prevention (CDC) already assisted state tobacco control initiatives, many state health departments turned to CDC for guidance on how to use Master Settlement Agreement monies. This article describes how CDC funded participatory research to establish local evidence and provided technical assistance for participatory program evaluation. The article (a) presents a telephone interview study of principal investigators (PIs) to determine how CDC could best facilitate participatory research and (b) identifies factors CDC considered to devise evaluation technical assistance that reflected local context. The interview study identified 8 areas where PIs needed CDC's support to undertake participatory research: continuity, timeliness, flexibility, clear and explicit expectations, appropriate and instructive accountability, creation of a vision for participatory research, tailored technical assistance, and enhancement of partner collaboration and support. These findings are being used to inform CDC's research funding. Meanwhile, user-driven technical assistance for participatory evaluation is being accessed by many states.

Economics of mass media health campaigns with health-related product distribution: a community guide systematic review.

CONTEXT: The objective of this systematic review was to determine the costs, benefits, and overall economic value of communication campaigns that included mass media and distribution of specified health-related products at reduced price or free of charge. EVIDENCE ACQUISITION: Economic evaluation studies from a literature search from January 1980 to December 2009 were screened and abstracted following systematic economic review methods developed by The Community Guide. Data were analyzed in 2011. EVIDENCE SYNTHESIS: The economic evidence was grouped and assessed by type of product distributed and health risk addressed. A total of 15 evaluation studies were included in the economic review, involving campaigns promoting the use of child car seats or booster seats, pedometers, condoms, recreational safety helmets, and nicotine replacement therapy. CONCLUSIONS: Economic merits of the intervention could not be determined for health communication campaigns associated with use of recreational helmets, child car seats, and pedometers, primarily because available economic information and analyses were incomplete. There is some evidence that campaigns with free condom distribution to promote safer sex practices were cost-effective among high-risk populations and the cost per quit achieved in campaigns promoting tobacco cessation with nicotine replacement therapy products may translate to a cost per quality-adjusted life-year less than $50,000. Many interventions were publicly funded trials or programs, and the failure to properly evaluate their economic cost and benefit is a serious gap in the science and practice of public health.

Mass media health communication campaigns combined with health-related product distribution: a community guide systematic review.

CONTEXT: Health communication campaigns including mass media and health-related product distribution have been used to reduce mortality and morbidity through behavior change. The intervention is defined as having two core components reflecting two social marketing principles: (1) promoting behavior change through multiple communication channels, one being mass media, and (2) distributing a free or reduced-price product that facilitates adoption and maintenance of healthy behavior change, sustains cessation of harmful behaviors, or protects against behavior-related disease or injury. EVIDENCE ACQUISITION: Using methods previously developed for the Community Guide, a systematic review (search period, January 1980-December 2009) was conducted to evaluate the effectiveness of health communication campaigns that use multiple channels, including mass media, and distribute health-related products. The primary outcome of interest was use of distributed health-related products. EVIDENCE SYNTHESIS: Twenty-two studies that met Community Guide quality criteria were analyzed in 2010. Most studies showed favorable behavior change effects on health-related product use (a median increase of 8.4 percentage points). By product category, median increases in desired behaviors ranged from 4.0 percentage points for condom promotion and distribution campaigns to 10.0 percentage points for smoking-cessation campaigns. CONCLUSIONS: Health communication campaigns that combine mass media and other communication channels with distribution of free or reduced-price health-related products are effective in improving healthy behaviors. This intervention is expected to be applicable across U.S. demographic groups, with appropriate population targeting. The ability to draw more specific conclusions about other important social marketing practices is constrained by limited reporting of intervention components and characteristics.

Complex interventions and their implications for systematic reviews: a pragmatic approach.

Complex interventions present unique challenges for systematic reviews. Current debates tend to center around describing complexity, rather than providing guidance on what to do about it. At a series of meetings during 2009-2012, we met to review the challenges and practical steps reviewer could take to incorporate a complexity perspective into systematic reviews. Based on this, we outline a pragmatic approach to dealing with complexity, beginning, as for any review, with clearly defining the research question(s). We argue that reviews of complex interventions can themselves be simple or complex, depending on the question to be answered. In systematic reviews and evaluations of complex interventions, it will be helpful to start by identifying the sources of complexity, then mapping aspects of complexity in the intervention onto the appropriate sources of evidence (such as specific types of quantitative or qualitative study). Although we focus on systematic reviews, the general approach is also applicable to primary research that is aimed at evaluating complex interventions. Although the examples are drawn from health care, the approach may also be applied to other sectors (e.g., social policy or international development). We end by concluding that systematic reviews should follow the principle of Occam's razor: explanations should be as complex as they need to be and no more.