3.5 How effective is the policy or intervention?

Indicators used to assess the effectiveness of a policy or intervention are determined by the anticipated health outcome. For example, effectiveness of a diabetes prevention intervention is determined by assessing diabetes incidence in the population of interest, while the effectiveness of a new policy to encourage physical activity in schools may be determined by assessing the levels of high intensity exercise carried out by students. Given the huge variety of health outcomes assessed in NCD prevention and control, and given the objectives of this guide, it is beyond the scope of this guide to explore the wide range of tools and methods for the assessment of health outcomes.

Note that effectiveness is affected by implementation. Therefore, when assessing the effectiveness of a policy or intervention we are not assessing the intervention’s absolute effectiveness – but are only assessing its effectiveness as implemented. As such, it is inadequate to conclude that a policy or intervention is effective per se without providing information about its implementation; the same policy or intervention could be implemented elsewhere with very different health outcomes. Also note that implementation outcomes differ from clinical treatment outcomes, and both should be assessed.^{(15, 95, 97)}

Implementation outcomes have three important functions. First, they serve as indicators of the implementation success. Second, they are proximal indicators of implementation processes. And third, they are key intermediate outcomes⁽⁸⁶⁾ in relation to service system or clinical outcomes in treatment effectiveness and quality of care research.