The absolute risk of an outcome associated with exposure to an agent (e.g. receiving a particular therapy) is of less value than the difference or change in absolute risk between those exposed and not exposed. This difference, or absolute risk reduction in the case that the agent (therapy) confers protection to the outcome of interest, is of fundamental importance to economic evaluation as it drives the incremental effect in an incremental cost-effectiveness ratio (ICER). ARR is also the reciprocal of Numbers Needed to Treat (NNT), which is used to communicate effectiveness in evidence-based medicine.

How to cite: Absolute Risk Reduction (ARR) [online]. (2016). York; York Health Economics Consortium; 2016.

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