risk factor and treatment benefit metrics

see also:

• epidemiology

absolute risk = (Event rate in those exposed - Event rate in those not exposed)

relative risk = (Event rate in those exposed - Event rate in those not exposed) / (Event rate in those NOT exposed)

number needed to harm = 1 / (Event rate in those exposed - Event rate in those not exposed)

risk ratio = (Event rate in those exposed) / (Event rate in those NOT exposed)

odds ratio = (number events in exposed / number of no event in exposed) / (number events in non-exposed / number of no event in non-exposed)

attributable risk fraction = (Event rate in those exposed - Event rate in those not exposed) / (Event rate in those exposed)

PAF combines both the relative risk of an event with respect to a factor, with the prevalence of the factor in the population.

see PAF

absolute risk reduction = (Event rate in control group - Event rate in treatment group)

relative risk reduction = (Event rate in control group - Event rate in treatment group) / (Event rate in control group)

number needed to treat (NNT) = 1 / (Event rate in control group - Event rate in treatment group)

risk ratio = (Event rate in treatment group) / (Event rate in control group)

odds ratio = (number events in treatment group / number of no event in treatment group) / (number events in control group / number of no event in control group)

preventable fraction among the unexposed = (Event rate in control group - Event rate in treatment group) / (Event rate in control group)