Benefit-risk ratio

This benefit-risk ratio(BRR) is illustrated using the natalizumab versus placebo example. The BRR is calculated for each risk against the two medical benefits, reduction in relapse (Table 16) and reduction in disability progression (Table 17), using only the mean risk differences to illustrate the concept. The mean risk differences for benefits are reversed to place them on the same scale as risks to allow them to be directly compared i.e. reduction in relapse rate is 0.12 and slowdown in disability progression is 0.26. They are then inverted to give NNT. The risk flu-like reactions is also reversed because natalizumab appears to be more favourable than placebo, and inverted to give NNT. All other risks are also then inverted to give NNH.

The BRRs, given to 3 decimal places, are therefore equivalent to NNT/NNH, and therefore a value less than 1 implies the benefit is greater than the risk. However, this method assumes that each benefit and risk is of the same importance as the weights are not taken into account.

Table 16 Benefit-Risk Ratio for Reduction in Relapse. Natalizumab versus placebo (Comparator) at time of approval

Table 17 Benefit-Risk Ratio for Slowdown in Disability Progression. Natalizumab versus placebo (Comparator) at time of approval