Summary
Objectives:
Different approaches to partition the attributable risk into exposure-specific components
are methodologically evaluated.
Methods:
Two methods of partitioning the attributable risk in a multifactorial situation have
been suggested. One is based on a solution adopted from game theory, the Shapley value,
whereas the other recently suggested approach uses a heuristically motivated proportional
weighting scheme. These two concepts are reviewed and compared in a situation with
three exposure factors. A hypothetical numerical example is discussed illustrating
differences in the case of complex interaction structures.
Results:
The two methods are found to differ in two critical features that affect the outcome
of partitioning: i) including or ignoring the full interaction structure between exposure
factors involved in the partitioning, ii) using an equal or proportional weighting
scheme for the marginal excess risks of the exposures. As a result, not only the individual
partial attributable risks for the exposure factors may be quantitatively different
between the methods, but also their ranking depends on the partitioning approach.
Conclusions:
The epidemiologic properties of the partitioning procedure based on the Shapley value
are known and fit to the needs of epidemiologic applications. The alternative approach
recently suggested can lead to considerably different results. As long as its epidemiologic
properties are not fully understood, the traditional partitioning method should be
given preference in practical applications.
Keywords
Attributable fraction - partial attributable risk - Shapley value - proportional risk
allocation
