title: Tracking and tracing of participants in two large cancer screening trials.
abstract: BACKGROUND
  Many clinical trials rely on participant report to first learn about study events. It is therefore important to have current contact information and the ability to locate participants should information become outdated. The Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial (PLCO) and the Lung Screening Study (LSS) component of the National Lung Screening Trial, two large randomized cancer screening trials, enrolled almost 190,000 participants on whom annual contact was necessary. Ten screening centers participated in both trials. Centers developed methods to track participants and trace them when necessary. We describe the methods used to keep track of participants and trace them when lost, and the extent to which each method was used.
  
  
  METHODS
  Screening center coordinators were asked, using a self-administered paper questionnaire, to rate the extent to which specific tracking and tracing methods were used.
  
  
  RESULTS
  Many methods were used by the screening centers, including telephone calls, mail, and internet searches. The most extensively used methods involved telephoning the participant on his or her home or cell phone, or telephoning a person identified by the participant as someone who would know about the participant's whereabouts. Internet searches were used extensively as well; these included searches on names, reverse-lookup searches (on addresses or telephone numbers) and searches of the Social Security Death Index. Over time, the percentage of participants requiring tracing decreased.
  
  
  CONCLUSIONS
  Telephone communication and internet services were useful in keeping track of PLCO and LSS participants and tracing them when contact information was no longer valid.
authors.affiliation: National Cancer Institute, Bethesda, MD 20892-7344, USA. marcusp@mail.nih.gov
authors.forename: Pamela M
authors.initials: PM
authors.lastname: Marcus
authors.forename: Jeffery
authors.initials: J
authors.lastname: Childs
authors.forename: Betsy
authors.initials: B
authors.lastname: Gahagan
authors.forename: Lisa H
authors.initials: LH
authors.lastname: Gren
mesh_terms: D055088:Early Detection of Cancer; D006801:Humans; D020407:Internet; D059012:Lost to Follow-Up; D008403:Mass Screening; D009369:Neoplasms / Q000175:diagnosis*; D016032:Randomized Controlled Trials as Topic / Q000379:methods*; D011795:Surveys and Questionnaires; D013689:Telephone