دانلود گزارش کارورزی و کار آموزی

چکیده : 

The validation of surrogate endpoints has been studied by Prentice (1989). He presented a definition

as well as a set of criteria, which are equivalent only if the surrogate and true endpoints are binary.

Freedman et al. (1992) supplemented these criteria with the so-called ‘proportion explained’. Buyse

and Molenberghs (1998) proposed replacing the proportion explained by two quantities: (1) the relative

effect linking the effect of treatment on both endpoints and (2) an individual-level measure of agreement

between both endpoints. The latter quantity carries over when data are available on several randomized

trials, while the former can be extended to be a trial-level measure of agreement between the effects

of treatment of both endpoints. This approach suggests a new method for the validation of surrogate

endpoints, and naturally leads to the prediction of the effect of treatment upon the true endpoint, given

its observed effect upon the surrogate endpoint. These ideas are illustrated using data from two sets of

multicenter trials: one comparing chemotherapy regimens for patients with advanced ovarian cancer, the

other comparing interferon-α with placebo for patients with age-related macular degeneration.