Health Services Research (HSR) Methods
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Relative Risk Reduction (RRR)

The relative, proportional reduction in a certain risk (ratio of bad outcome) between experimental and control groups.

RRR is the difference in risks (bad outcomes) between the two groups, expressed as a proportion by dividing the absolute risk reduction (ARR) among the treated group by risks in the untreated population.  RRR expresses the extent to which a treatment reduces the risk of interest, in comparison to patients not receiving the treatment.



Further Reading
Last, J. 1983. A Dictionary of Epidemiology, New York, NY: Oxford Medical Publications.

Berger, M. et al. 2003. Health Care, Cost, Quality, and Outcomes: ISPOR Book of Terms, Lawrenceville, NJ: International Society for Pharmacoeconomics and Outcomes Research.