Reduction in follow-up period of a study using criteria supplemental to death
Flandre, P.
Revue d'Epidemiologie et de Sante Publique 41(6): 494-500
1993
ISSN/ISBN: 0398-7620 PMID: 8296036 Document Number: 421981
This work concerns the estimation of the follow-up period reduction for patients involved in a survival study when an auxiliary event is also used as an endpoint. An estimation procedure has been proposed using a surrogate criterion as an addition to the main endpoint criterion. This procedure is a two-stage study and enables us to estimate the survival function by using both criteria simultaneously. With a model of disease progression including the surrogate criterion as well as the main endpoint, simple calculations assess the gain in time with the two-stage procedure by comparison with a one-stage procedure. This gain in time, expressed in terms of a reduction of the follow-up period, depends on the prevalence of the surrogate criterion and its impact on survival. In the last part of this paper we discuss the advantages and disadvantages of such a procedure in common practice.