Work out population attributable risk instantly with clear inputs, formula shown and shareable results.
Applies Levin's formula to convert exposure prevalence and relative risk into the share of cases attributable to the exposure.
Levin's formula
PAF = p(RR - 1) / (1 + p(RR - 1)), where p is exposure prevalence; attributable cases = PAF x total cases
Multiple causes can each be necessary for the same case, so fractions for different risk factors overlap.
Only if the relative risk is causal; applying it to a confounded association overstates preventable burden.