Risk Models in EPICURE Programs

The generalized risk models in these programs can be written as sums and products of terms (denoted by ) each of which is computed as a product of parametric functions of covariates which are referred to as subterms. In the geometric mixture models defined below, the definition of a term is further generalized to allow for excess risk terms of the form . If the 1 is omitted, the term will be called a relative risk term. Terms which can be either excess or relative risk will be denoted . Model specification involves indicating how terms are to be combined (the form of the model); the subterms to be included in each term in the model; and the variables to be included in each subterm. The models available in PEANUTS, PECAN, GMBO, and AMFIT include: a) the product additive excess model:

b) the product additive model:

c) the additive model:

d) the geometric mixture model:

e) the multiplicative model:

 The product additive excess model is the default. The mixing parameter  in the geometric mixture model is specified by the user and cannot be estimated directly. The multiplicative model is a special case of the geometric mixture model with . Using these models one can fit most commonly used hazard function or relative risk models.