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United States Department of Agriculture

Agricultural Research Service


Location: Jean Mayer Human Nutrition Research Center On Aging

Title: Comprehensive assessment of long-term effects of reducing intake of energy phase 2 (CALERIE Phase 2) screening and recruitment: Methods and results

item Stewart, Tiffany
item Bhapkar, Manju
item Das, Sai Krupa
item Galan, Katherine
item Martin, Corby
item Mcadams, Luanne
item Pieper, Carl
item Redman, Leanne
item Roberts, Susan
item Stein, Rick

Submitted to: Contemporary Clinical Trials
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/29/2012
Publication Date: 1/1/2013
Citation: Stewart, T.M., Bhapkar, M., Das, S., Galan, K., Martin, C.K., Mcadams, L., Pieper, C., Redman, L.M., Roberts, S.B., Stein, R.I. 2013. Comprehensive assessment of long-term effects of reducing intake of energy phase 2 (CALERIE Phase 2) screening and recruitment: Methods and results. Contemporary Clinical Trials. 34(1):10-20.

Interpretive Summary: The Comprehensive Assessment of the Long-term Effects of Reducing Intake of Energy Phase 2 (CALERIE) is the second part of a study that is trying to determine how a diet with lower amounts of calories will affect non-obese people (people who are not very overweight). This is important because eating fewer calories may impact health, but we do not know the side effects of a diet like this. Recruitment for clinical research studies is frequently challenging. This paper describes the successful recruitment and enrollment process for the CALERIE study of human calorie restriction, which enrolled and randomized 229 individuals to ad libitum or caloric restriction regimens for a 2 year study. First, flyers were handed out, advertisements on radio and TV were aired, phone calls were made, and letters were mailed out. People who responded to these then had to be tested and interviewed in order to make sure that they had characteristics that were required for participation in the study. These included characteristics like being comfortable with your body. Depending on the area, researchers found that the most successful ways to find participants were through flyers, newspapers and subway advertisements, and Craigslist (a website). Phone calls and TV commercials also worked well. Researchers found that by making volunteers do several tests that talk about many topics, they were able to find healthy volunteers who would be able to participate in the study for a long time. This paper is important because it records the methods for finding participants in a study like this that worked, and also records the problems researchers faced in finding participants. This study demonstrates that with intensive techniques, recruitment for even challenging studies is possible, allowing investigators to achieve protocol goals for results generation. These methods can then be used in future studies.

Technical Abstract: The Comprehensive Assessment of the Long-term Effects of Reducing Intake of Energy Phase 2 (CALERIE) study is a systematic investigation of sustained 25% calorie restriction (CR) in non-obese humans. CALERIE is a multicenter (3 clinical sites, one coordinating center), parallel group, randomized controlled trial. Participants were recruited, screened, and randomized to the CR or control group with a 2:1 allocation. Inclusion criteria included ages 21-50years for men and 21-47years for women, and a body mass index (BMI) of 22.0=BMI<28.0kg/m(2). Exclusion criteria included abnormal laboratory markers, significant medical conditions, psychiatric/behavioral problems, and an inability to adhere to the rigors of the evaluation/intervention schedule. A multi-stage screening process (telephone screen and 3 in-clinic visits) was applied to identify eligible participants. Recruitment was effective and enrollment targets were met on time. 10,856 individuals contacted the clinical sites, of whom 9787 (90%) failed one or more eligibility criteria. Of the 1069 volunteers who started the in-clinic screening, 831 (78%) were either ineligible or dropped. 238 volunteers were enrolled (i.e., initiated the baseline evaluations), 220 were randomized, and 218 started the assigned intervention (2% from the first screening step). This study offered lessons for future multi-center trials engaging non-disease populations. Recruitment strategies must be tailored to specific sites. A multi-disciplinary screening process should be applied to address medical, physical, and psychological/behavioral suitability of participants. Finally, a multi-step screening process with simple criteria first, followed by more elaborate procedures has the potential to reduce the use of study resources.

Last Modified: 06/22/2017
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