SurvRegCensCov: Weibull Regression for a Right-Censored Endpoint with a   Censored Covariate
  Biomarker data is often subject to limits of quantification and/or limits of detection. Statistically, this corresponds to left- or interval-censoring. To be able to associate a censored time-to-event endpoint to a biomarker covariate, the R package SurvRegCensCov provides software for Weibull regression for a right-censored endpoint, one interval-censored, and an arbitrary number of non-censored covariates. Furthermore, the package provides functions to estimate canonical parameters from censored samples based on several distributional assumptions, and a function to switch between different parametrizations used in R for Weibull regression. We illustrate the new software by applying it to assess Prentice's criteria for surrogacy in data simulated from a randomized clinical registration trial. 
Stanislas Hubeaux and Kaspar Rufibach
stat.CO