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Rigorous control conditions diminish treatment effects in weight loss-randomized controlled trials

International Journal of Obesity volume 40, pages 895–898 (2016)Cite this article

Subjects

Abstract

Background:

It has not been established whether control conditions with large weight losses (WLs) diminish expected treatment effects in WL or prevention of weight gain (PWG)-randomized controlled trials (RCTs).

Subjects/Methods:

We performed a meta-analysis of 239 WL/PWG RCTs that include a control group and at least one treatment group. A maximum likelihood meta-analysis framework was used to model and understand the relationship between treatment effects and control group outcomes.

Results:

Under the informed model, an increase in control group WL of 1 kg corresponds with an expected shrinkage of the treatment effect by 0.309 kg (95% confidence interval (−0.480, −0.138), P=0.00081); this result is robust against violations of the model assumptions.

Conclusions:

We find that control conditions with large WLs diminish expected treatment effects. Our investigation may be helpful to clinicians as they design future WL/PWG studies.

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Acknowledgements

DBA conceived the analysis. GRC advised on study design and data collection/coding approaches. KAK and OA collected and coded the data. KAK performed the multiple imputation of the missing data. JAD coded and performed the analyses. All authors were involved in writing the paper and had final approval of the submitted and published versions. We would like to thank Christopher Schmid for comments and feedback that helped improve the manuscript. We would also like to thank Tiffany Carson, Katherine Ingram and Firas Abbas for assistance in data collection and coding. This work was primarily funded by Grant Number R01DK078826, with other support from T32HL072757, P30DK056336, T32HL007457, T32HL079888 and T32DK062710. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NHLBI, NIDDK or the National Institutes of Health.

Author information

Authors and Affiliations

  1. Department of Nutritional Sciences, College of Human Sciences, Texas Tech University, Lubbock, TX, USA

    J A Dawson

  2. Office of Energetics, School of Public Health, University of Alabama at Birmingham, Birmingham, AL, USA

    K A Kaiser & D B Allison

  3. Nutrition Obesity Research Center, University of Alabama at Birmingham, Birmingham, AL, USA

    K A Kaiser, O Affuso & D B Allison

  4. Department of Epidemiology, School of Public Health, University of Alabama at Birmingham, Birmingham, AL, USA

    O Affuso

  5. Department of Biostatistics, Section on Research Methods and Clinical Trials, School of Public Health, University of Alabama at Birmingham, Birmingham, AL, USA

    G R Cutter

Authors
  1. J A Dawson
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  2. K A Kaiser
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  3. O Affuso
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  4. G R Cutter
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  5. D B Allison
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Corresponding author

Correspondence to J A Dawson.

Ethics declarations

Competing interests

JAD and KAK have no conflicts of interest to declare. OA has received consulting fees and grants from organizations interested in obesity interventions. GRC has had the following consulting or DSMB commitments within the past 12 months: Apotek, Biogen-Idec, Cleveland Clinic, Glaxo Smith Klein Pharmaceuticals, Gilead Pharmaceuticals, Modigenetech/Prolor, Merck/Ono Pharmaceuticals, Merck, Neuren, PCT Bio, Revalesio, Sanofi-Aventis, Teva, Vivus, NHLBI (Protocol Review Committee), NINDS, NMSS and NICHD (OPRU oversight committee). In addition, GRC has consulted, recieved speaking fees or acted as part of an advisory boards for the following: Alexion, Allozyne, Bayer, Celgene, Coronado Biosciences, Consortium of MS Centers (grant), Diogenix, Klein-Buendel Incorporated, Medimmune, Novartis, Nuron Biotech, Receptos, Spiniflex Pharmaceuticals and Teva pharmaceuticals. GRC is employed by the University of Alabama at Birmingham and is President of Pythagoras, Inc., a private consulting company located in Birmingham AL. DBA has received consulting fees and his university has received gifts, grants and donations from multiple non-profit and for-profit organizations with interests in obesity trials including food and pharmaceutical companies.

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Dawson, J., Kaiser, K., Affuso, O. et al. Rigorous control conditions diminish treatment effects in weight loss-randomized controlled trials. Int J Obes 40, 895–898 (2016). https://doi.org/10.1038/ijo.2015.212

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