Trade-off Indices

BRR (Benefit-Risk Ratio)


1. Description

BRR (Benefit Risk Ratio) is a simple trade-off metric which divides benefits by risks, therefore assumes equal importance of benefits and risks.[1][2][3] For a given benefit with rates and a given risk with rates , . This is conceptually the expected "multiples" of benefit per unit risk .

2. Evaluation

2.1 Principle
  • It is a very simple approach based on probabilities and is easy to understand.
  • BRR is not transparent for benefit-risk assessment when used in its simplest form.
  • To use BRR in a benefit-risk assessment, an equilibrium point at which the benefit and risk are considered equal should be established.
  • The equilibrium point is then used to determine whether benefits outweigh risks, insufficient to conclude, or that risks outweigh benefits - this implicitly incorporates weighting into the expression.

2.2 Features
  • The features of BRR are very similar to those of NNT.
  • BRR can only deal with one benefit and one risk at a time.
2.3 Visualisation
  • There is none proposed specifically for BRR. Any suitable visualisation can be used.

2.4 Assessability and accessibility
  • BRR is only acceptable and interpretable if the assumption of equal weightings for benefit and risk hold.
  • It provides a straightforward comparison of benefit and risk but may be unreliable when used in its simplest form.
  • BRR can be derived from good statistical models based on high quality evidence data or through simulations.
  • With high quality evidence, the use of BRR is more attractive and meaningful in the context of drug benefit-risk assessment.
  • Taking ratios of other benefit and risk metrics for example the NNT to NNH could also be regarded as BRR, where the strengths and weaknesses of the unitary metrics used are also inherited.

This method was tested in the Efalizumab, Natalizumab, Rimonabant, and Telithromycin case studies.

3. References

[1] Chuang-Stein C, Entsuah R, Pritchett Y. Measures for conducting comparative benefit: Risk assessment. Drug Information Journal 2008;42(3):223-33.
[2] Korting H, Schafer-Korting M. The benefit-risk ratio. A handbook for the rational use of potentially hazardous drugs. Boca Raton: CRC Press LLC; 1999.

[3] Payne JT, Loken MK. A survey of the benefits and risks in the practice of radiology. CRC Critical Reviews in Clinical Radiology and Nuclear Medicine 1975;6(3):425-39.