Journal article
Missing Data in Randomized Clinical Trials for Weight Loss: Scope of the Problem, State of the Field, and Performance of Statistical Methods
PloS one, Vol.4(8), pp.e6624-e6624
08/13/2009
DOI: 10.1371/journal.pone.0006624
PMCID: PMC2720539
PMID: 19675667
Abstract
Background
Dropouts and missing data are nearly-ubiquitous in obesity randomized controlled trails, threatening validity and generalizability of conclusions. Herein, we meta-analytically evaluate the extent of missing data, the frequency with which various analytic methods are employed to accommodate dropouts, and the performance of multiple statistical methods.
Methodology/Principal Findings
We searched PubMed and Cochrane databases (2000–2006) for articles published in English and manually searched bibliographic references. Articles of pharmaceutical randomized controlled trials with weight loss or weight gain prevention as major endpoints were included. Two authors independently reviewed each publication for inclusion. 121 articles met the inclusion criteria. Two authors independently extracted treatment, sample size, drop-out rates, study duration, and statistical method used to handle missing data from all articles and resolved disagreements by consensus. In the meta-analysis, drop-out rates were substantial with the survival (non-dropout) rates being approximated by an exponential decay curve (e−λt) where λ was estimated to be .0088 (95% bootstrap confidence interval: .0076 to .0100) and t represents time in weeks. The estimated drop-out rate at 1 year was 37%. Most studies used last observation carried forward as the primary analytic method to handle missing data. We also obtained 12 raw obesity randomized controlled trial datasets for empirical analyses. Analyses of raw randomized controlled trial data suggested that both mixed models and multiple imputation performed well, but that multiple imputation may be more robust when missing data are extensive.
Conclusion/Significance
Our analysis offers an equation for predictions of dropout rates useful for future study planning. Our raw data analyses suggests that multiple imputation is better than other methods for handling missing data in obesity randomized controlled trials, followed closely by mixed models. We suggest these methods supplant last observation carried forward as the primary method of analysis.
Details
- Title: Subtitle
- Missing Data in Randomized Clinical Trials for Weight Loss: Scope of the Problem, State of the Field, and Performance of Statistical Methods
- Creators
- Mai A Elobeid - University of Oxford, United KingdomMiguel A Padilla - University of Oxford, United KingdomTheresa McVie - University of Oxford, United KingdomOlivia Thomas - University of Oxford, United KingdomDavid W Brock - University of Oxford, United KingdomBret Musser - University of Oxford, United KingdomKaifeng Lu - University of Oxford, United KingdomChristopher S Coffey - University of Iowa, BiostatisticsRenee A Desmond - University of Oxford, United KingdomMarie-Pierre St-Onge - University of Oxford, United KingdomKishore M Gadde - University of Oxford, United KingdomSteven B Heymsfield - University of Oxford, United KingdomDavid B Allison - University of Oxford, United Kingdom
- Resource Type
- Journal article
- Publication Details
- PloS one, Vol.4(8), pp.e6624-e6624
- DOI
- 10.1371/journal.pone.0006624
- PMID
- 19675667
- PMCID
- PMC2720539
- NLM abbreviation
- PLoS One
- ISSN
- 1932-6203
- eISSN
- 1932-6203
- Publisher
- Public Library of Science
- Alternative title
- Missing Data in Obesity RCTs
- Language
- English
- Date published
- 08/13/2009
- Academic Unit
- Biostatistics
- Record Identifier
- 9984215552602771
Metrics
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