ABSTRACT
Multi-state models have become increasingly popular as a convenient tool to describe the follow-up of patients or, more generally, individuals at risk for certain events. Per Kragh Andersen has been one of the main promotors of multi-state models. It is quite interesting to read the section on multi-state models in his contribution to the Tenth Anniversary Issue of Statistics In Medicine in 1991 (Andersen 1991), where he describes multi-state models as one of the important developments in the 1980’s. Comprehensive reviews are given by Commenges (1999), Hougaard (1999), Andersen & Keiding (2002), Putter et al. (2007). Interesting applications in the field of bone marrow transplantation are given in the papers by the group around Klein, Keiding and Andersen (Klein et al. 1994, Keiding et al. 2001, Klein & Shu 2002). The first paper in this area from the Leiden department of Medical Statistics is Hansen et al. (1994) on multi-state models for liver transplant patients.
