title: Definition of screening status in case-control studies of the efficacy of endoscopy.
authors.forename: N S
authors.initials: NS
authors.lastname: Weiss
mesh_terms: D016022:Case-Control Studies; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000401:mortality / Q000517:prevention & control*; D006801:Humans; D008403:Mass Screening; D014728:Veterans