Stopping the active intervention: CARET.
The Carotene and Retinol Efficacy Trial (CARET) was a large, multicenter randomized chemoprevention trial designed to test a combined lung cancer prevention agent in heavy smokers and workers exposed to asbestos. In January 1996, the CARET Steering Committee decided to stop the intervention due to an adverse effect. This paper describes the decision process used to apply the stopping rules and the activities engaged in by CARET participants and staff to implement the decision. The most important activity was to draft and mail a letter to the participants informing them of the disappointing CARET results and asking them to stop taking the study vitamins and to return any unused study vitamins. The steering committee, with the support of the National Cancer Institute, planned to follow participants for disease endpoints and smoking behavior for 5 years. These activities led to smooth closure of active intervention and maintained high retention rates during the transition.
Bowen
Deborah J
DJ
Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA. dbowen@fhcrc.org
Thornquist
Mark
M
Anderson
Karen
K
Barnett
Matt
M
Powell
Corinne
C
Goodman
Gary
G
Omenn
Gilbert
G
D001194:Asbestos / Q000009:adverse effects; D018890:Chemoprevention; D026661:Clinical Trials Data Monitoring Committees; D003627:Data Interpretation, Statistical; D004341:Drug Evaluation / Q000379:methods; D004992:Ethics, Medical; D006801:Humans; D008175:Lung Neoplasms / Q000453:epidemiology / Q000517:prevention & control*; D016273:Occupational Exposure / Q000009:adverse effects; D016032:Randomized Controlled Trials as Topic / Q000592:standards*; D012907:Smoking / Q000009:adverse effects; D036302:Therapeutic Human Experimentation / Q000941:ethics*; D014481:United States / Q000453:epidemiology; D014801:Vitamin A / Q000627:therapeutic use; D019207:beta Carotene / Q000627:therapeutic use
D019207:beta Carotene; D014801:Vitamin A; D001194:Asbestos