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Rationale for Study


 • Eligibility Criteria

 • Recruitment

 • Intervention

 • Follow-up

 • Data Collection

Primary Publications


Six study centers performed participant recruitment under the direction of the Coordinating Center, located in Seattle, Washington. Study centers were located in Baltimore, Maryland; Irvine, California; Groton, Connecticut (referred to as the New Haven Study Center); Portland, Oregon; San Francisco, California; and Seattle, Washington. Recruitment began in 1985 in Seattle with two pilot studies (one for asbestos-exposed participants and the other for heavy smokers). Pilot recruitment ended in 1988, at which time the full-scale efficacy trial was initiated. Accrual was completed in September 1994. The Baltimore, New Haven, and San Francisco Study Centers recruited primarily asbestos-exposed participants. In August 1992, the CARET Steering Committee approved the recruitment at these three study centers of smoker-eligible spouses and other members of the asbestos-exposed participants' households who met the heavy smoker eligibility criteria for CARET. Seattle and Portland recruited a small number of asbestos-exposed participants, but their primary goals were for heavy smokers. Irvine recruited only heavy smokers. Participants randomized after July 1988 into CARET are referred to as the Efficacy cohort. The participants in the pilot studies were incorporated into CARET as the Vanguard cohort. The figure below shows the timing of adding study centers and their accrual goals (total accrual goal 17,510).

CARET Study Center Funding Timeline and Accrual Goals

The initial contact with a potential participant was usually a mailing that included an introductory letter, an interest survey, and a study fact sheet. The interest survey included questions about the individual's age, sex, smoking status and smoking history, asbestos exposure, and potential interest in joining the study. The study center reviewed the returned interest surveys and screened out ineligibles. Study centers telephoned individuals who were not clearly ineligible. The purpose of the phone call was to review or clarify information on the interest survey, ask questions about the study exclusion criteria, and schedule an appointment for the First Visit for those who seemed to be eligible.

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