flexsurv

flexsurv is an R package designed for fitting flexible parametric survival models. These models are a powerful extension of traditional survival analysis methods, offering greater flexibility in modeling the baseline hazard function without making rigid assumptions about its shape. The package allows for the specification of various parametric distributions for the survival times, including the Weibull, Gompertz, and generalized gamma distributions, as well as extensions to these.

A key feature of flexsurv is its ability to incorporate time-dependent covariates and to handle different types of censoring. The underlying methodology relies on splines to model the log of the cumulative hazard function, which enables the estimation of complex survival curves. This approach allows for more accurate predictions and a better understanding of the factors influencing survival over time.

The package provides functions for fitting various types of survival models, including standard survival regression, competing risks models, and multi-state models. It also includes tools for model diagnostics, such as comparing models using information criteria and visualizing predicted survival curves. flexsurv is widely used in medical research and other fields where survival data analysis is crucial, offering a robust and adaptable framework for exploring survival patterns.