Association of run-in periods with weight loss in obesity randomized controlled trials

Authors

  • O. Affuso,

    Corresponding author
    1. Department of Epidemiology, School of Public Health, University of Alabama at Birmingham, Birmingham, AL, USA
    2. Nutrition Obesity Research Center, University of Alabama at Birmingham, Birmingham, AL, USA
    • Address for correspondence: O Affuso, Department of Epidemiology, University of Alabama at Birmingham, Ryals Public Health Building, Room 220E, Birmingham, AL 35294, USA.

      E-mail: oaffuso@uab.edu

      or DB Allison, Office of Energetics, University of Alabama at Birmingham, Ryals Public Health Building, Room 140J, Birmingham, AL 35294, USA.

      E-mail: dallison@uab.edu

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  • K. A. Kaiser,

    1. Office of Energetics, School of Public Health, University of Alabama at Birmingham, Birmingham, AL, USA
    2. Nutrition Obesity Research Center, University of Alabama at Birmingham, Birmingham, AL, USA
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  • T. L. Carson,

    1. Division of Preventive Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
    2. Nutrition Obesity Research Center, University of Alabama at Birmingham, Birmingham, AL, USA
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  • K. H. Ingram,

    1. Department of Exercise Science and Sports Management, Kennesaw State University, Kennesaw, GA, USA
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  • M. Schwiers,

    1. Ethicon Endo-Surgery, Inc., Cincinnati, OH, USA
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  • H. Robertson,

    1. Seton Healthcare Family, Austin, TX, USA
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  • F. Abbas,

    1. Department of Internal Medicine, Maricopa Integrated Health System, Phoenix, AZ, USA
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  • D. B. Allison

    Corresponding author
    1. Office of Energetics, School of Public Health, University of Alabama at Birmingham, Birmingham, AL, USA
    2. Nutrition Obesity Research Center, University of Alabama at Birmingham, Birmingham, AL, USA
    • Address for correspondence: O Affuso, Department of Epidemiology, University of Alabama at Birmingham, Ryals Public Health Building, Room 220E, Birmingham, AL 35294, USA.

      E-mail: oaffuso@uab.edu

      or DB Allison, Office of Energetics, University of Alabama at Birmingham, Ryals Public Health Building, Room 140J, Birmingham, AL 35294, USA.

      E-mail: dallison@uab.edu

    Search for more papers by this author

  • Financial disclosures: Dr. Affuso has received consulting fees and grants from organizations interested in obesity interventions. Dr. Allison has received book royalties, consulting payments, grants and donations from numerous for-profit and not-for-profit entities with interests in obesity RCTs.

Summary

Study-level design characteristics that inform the optimal design of obesity randomized controlled trials (RCTs) have been examined in few studies. A pre-randomization run-in period is one such design element that may influence weight loss. We examined 311 obesity RCTs published between 1 January 2007 and 1 July 2009 that examine d weight loss or weight gain prevention as a primary or secondary end-point. Variables included run-in period, pre-post intervention weight loss, study duration (time), intervention type, percent female and degree of obesity. Linear regression was used to estimate weight loss as a function of (i) run-in (yes/no) and (ii) run-in, time, percent female, body mass index and intervention type. Interaction terms were also examined. Approximately 19% (18.6%) of the studies included a run-in period, with pharmaceutical studies having the highest frequency. Although all intervention types were associated with weight loss (Mean = 2.80 kg, SD = 3.52), the inclusion of a pre-randomization run-in was associated with less weight loss (P = 0.0017) compared with studies that did not include a run-in period. However, this association was not consistent across intervention types. Our results imply that in trials primarily targeting weight loss in adults, run-in periods may not be beneficial for improving weight loss outcomes in interventions.

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