title: Quantification of the completeness of follow-up.
abstract: Completeness of follow-up is important, especially in clinical trials, since unequal follow-up in the treatment groups can bias the analysis of results. In survival studies, information on participants who do not complete the study is often omitted because their data can be included up to the time at which they were lost to follow-up. We propose a simple measure of completeness that is the ratio of the total observed person-time and the potential person-time of follow-up in a study. Our measure is easy to calculate, can be illustrated pictorially, and can be used to identify subgroups with especially poor follow-up.
authors.forename: Taane G
authors.initials: TG
authors.lastname: Clark
authors.forename: Douglas G
authors.initials: DG
authors.lastname: Altman
authors.forename: Bianca L
authors.initials: BL
authors.lastname: De Stavola
mesh_terms: D002986:Clinical Trials as Topic; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008105:Liver Cirrhosis, Biliary / Q000188:drug therapy* / Q000401:mortality; D009101:Multiple Myeloma / Q000188:drug therapy* / Q000401:mortality; D010051:Ovarian Neoplasms / Q000188:drug therapy* / Q000401:mortality; D016019:Survival Analysis