Software for semiparametric shared gamma and log-normal frailty models: An overview.

In survival analysis individuals are followed over some period and the time until the transition from an initial to a final state is of particular interest. An important tool for analyzing potential risk factors of this transition is the Cox proportional hazards model. This model requires homogeneity in the study population and independence between the observations. An extension of the Cox model to deal with both, unobserved heterogeneity and clustered survival data, are frailty models [1]. Different software are available for the analysis of shared frailty models such as coxph, coxme, phmm, frailtyPenal, SPGAM or SPLN3. This makes it difficult for the user to find the appropriate tool for the specific problem under investigation. To compare the performance of the aforementioned software a large simulation study was conducted. Advantages and limitations of the software are discussed in detail.