title: Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy Phase 2 (CALERIE Phase 2) screening and recruitment: methods and results.
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 21-50 years for men and 21-47 years for women, and a body mass index (BMI) of 22.0 ≤ BMI < 28.0 kg/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.
authors.affiliation: Pennington Biomedical Research Center, Baton Rouge, LA 70808, United States. tiffany.stewart@pbrc.edu
authors.forename: T M
authors.initials: TM
authors.lastname: Stewart
authors.forename: M
authors.initials: M
authors.lastname: Bhapkar
authors.forename: S
authors.initials: S
authors.lastname: Das
authors.forename: K
authors.initials: K
authors.lastname: Galan
authors.forename: C K
authors.initials: CK
authors.lastname: Martin
authors.forename: L
authors.initials: L
authors.lastname: McAdams
authors.forename: C
authors.initials: C
authors.lastname: Pieper
authors.forename: L
authors.initials: L
authors.lastname: Redman
authors.forename: S
authors.initials: S
authors.lastname: Roberts
authors.forename: R I
authors.initials: RI
authors.lastname: Stein
authors.forename: J
authors.initials: J
authors.lastname: Rochon
authors.forename: D A
authors.initials: DA
authors.lastname: Williamson
mesh_terms: D000328:Adult; D015992:Body Mass Index; D031204:Caloric Restriction / Q000379:methods*; D002149:Energy Intake; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000178:diet therapy* / Q000378:metabolism; D018579:Patient Selection; D016032:Randomized Controlled Trials as Topic / Q000379:methods*; D055815:Young Adult