REVIEW OF THE EVIDENCE

The committee identified a primary prevention, population-based approach to be the most viable long-term strategy for reducing obesity and its chronic disease burdens. Examples of the effectiveness of primary prevention interventions include smoking cessation to reduce lung cancer incidence, condom use to lower HIV transmission, and fruit and vegetable consumption to prevent cancer and cardiovascular diseases (CVDs) (Kroke et al., 2003; WHO, 2003).

There is no single acceptable standard, however, for assessing the entire range of prevention interventions and programs (Kellam and Langevin, 2003). Each phase of prevention research involves specific criteria for evidence and a variety of possible research designs. This is often a process whereby the preceding phase of research informs the subsequent generation of research—from efficacy to effectiveness, sustainability, going-to-scale, and, finally, sustaining system-wide9 (Figure 3-3). Numerous evidence-based prevention strategies are currently being used, though their focus—whether on individuals, institutions, or societal structures—can vary (Kellam and Langevin, 2003).

An Evidence-Based Medicine Approach

Evidence-based medicine is a valuable concept for informing clinical medicine that provides universally accepted standards for testing the scientific method and developing clinical practice guidelines (Harris et al., 2001; Heller and Page, 2002). This approach uses an accepted hierarchy of evidence—in accordance with its type, quality, and strength—to support recommendations (Table 3-3) (Harris et al., 2001; Kroke et al., 2003), and it establishes a cause-and-effect relationship guided by the principles of predictability, replicability, generalizability, and falsifiability. Predictability depends on a properly implemented intervention producing expected outcomes, a clear understanding of the intervention’s elements, and a cause-and-effect interaction among those elements (Tang et al., 2003). Replicability and generalizability rely on an intervention’s potential for

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Efficacy research addresses whether an intervention produces a beneficial impact under optimal conditions of implementation and scientific rigor. Effectiveness research tests an intervention under normal conditions such as those in which the intervention may be employed. Sustainability research assesses whether the training and support structures developed for effectiveness trials can work to continue the implementation of the intervention by other implementers and with other cohorts of the population. Going-to-scale research designs and tests methods of training, support, and assessment that can be implemented across an entire system. Sustaining system-wide research determines how to maintain high-quality standards for an entire program over the long term (Kellam and Langevin, 2003).



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