Evaluating frailty may complement APACHE II in estimating mortality in elderly patients admitted to the ICU after digestive surgery P. Ruiz de Gopegui Miguelena; M.T. Martínez Lamazares; L.M. Claraco Vega; M. Gurpegui Puente; I. González Almárcegui; P. Gutiérrez Ibañes; A. Carrillo López; C.M. Castiella García; J. Miguelena Hycka;