Absolute risk reduction in osteoporosis: assessing treatment efficacy by number needed to treat

Measuring the Size of a Treatment Effect: Relative Risk Reduction, Absolute Risk Reduction, and Number Needed to Treat

Hussein Hollands, MD, MS (epid) Peter J. Kertes, MD, CM, FRCS(C) The purpose of this review article is to outline a few concepts that are useful for interpreting the results of a randomized clinical trial (RCT). Specifically, we will focus on measures of the size of a treatment effect— relative risk ratio (RRR), absolute risk ratio, and number needed to treat (NNT). These concepts are important...

Reporting number needed to treat and absolute risk reduction in randomized controlled trials.

CONTEXT Ongoing efforts to improve the quality of reporting for randomized controlled trials (RCTs) include the Consolidated Standards of Reporting Trials (CONSORT) statement. We examined the frequency of explicit reporting of the number needed to treat (NNT) and the absolute risk reduction (ARR) in RCTs. METHODS Five frequently cited journals were investigated: Annals of Internal Medicine, B...

Tips for learners of evidence-based medicine: 1. Relative risk reduction, absolute risk reduction and number needed to treat.

Physicians, patients and policy-makers are influenced not only by the results of studies but also by how authors present the results. Depending on which measures of effect authors choose, the impact of an intervention may appear very large or quite small, even though the underlying data are the same. In this article we present 3 measures of effect — relative risk reduction, absolute risk reduct...

Number Needed to Treat

Number needed to treat (NNT); number needed to harm (NNH).