Weighing risks and benefits in treating the individual patient.

Treatments may cause both benefits and harms. In such cases, the size of the benefit (indicated by the NNT to prevent one target event) needs to be weighed against the harms. One way of doing this is to estimate a threshold NNT, based on the attributable risks of the adverse events and their RVs compared with the importance of the target event prevented. By comparing the NNT at a given baseline risk with the threshold NNT, a critical baseline risk is identified above which treatment benefits are expected to outweigh harms. The assignment of RVs to benefits and harms of treatment is a necessary and crucial step in making a treatment recommendation. Consideration of the determinants of the threshold NNT may assist clinicians and parents in the explicit use of underlying values when making treatment decisions.