Group sample sizes in nonregulated health care intervention trials described as randomized controlled trials were overly similar

We evaluated whether sample sizes in different arms of two-arm parallel group randomized controlled trials of nonregulated interventions were systematically closer in size than would plausibly occur by chance if simple randomization had been applied. We searched PubMed for trials of nonregulated hea...

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Bibliographic Details
Published in:Journal of clinical epidemiology 2020-04, Vol.120, p.8-16
Main Authors: Thombs, Brett D., Levis, Alexander W., Azar, Marleine, Saadat, Nazanin, Riehm, Kira E., Sanchez, Tatiana A., Chiovitti, Matthew J., Rice, Danielle B., Levis, Brooke, Fedoruk, Claire, Lyubenova, Anita, Malo Vázquez de Lara, Aurelio López, Kloda, Lorie A., Benedetti, Andrea, Shrier, Ian, Platt, Robert W., Kimmelman, Jonathan
Format: Article
Language:English
Subjects:
Behavioral sciences
Bias
Citation indexes
Clinical trials
Controlled trials
Delivery of Health Care - methods
Dietetics
Drug therapy
Epidemiology
Health care
Humans
Impact factors
Intervention
Medical equipment
Methods
National libraries
Nursing
Nutrition
Psychology
Randomization
Randomized controlled trials
Randomized Controlled Trials as Topic - statistics & numerical data
RCTs
Registration
Rehabilitation
Research Design - statistics & numerical data
Research reporting
Sample Size
Statistical analysis
Surgery
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Summary:We evaluated whether sample sizes in different arms of two-arm parallel group randomized controlled trials of nonregulated interventions were systematically closer in size than would plausibly occur by chance if simple randomization had been applied. We searched PubMed for trials of nonregulated health care interventions that did not report using restricted randomization from journals in behavioral sciences and psychology, nursing, nutrition and dietetics, rehabilitation, and surgery. We emailed trial authors to clarify randomization procedures. We identified 148 nonregulated intervention trials that indicated they used simple randomization. Difference in trial arm sizes was smaller than would be predicted by chance if simple randomization had occurred in all trials (P 
ISSN:0895-4356
1878-5921
DOI:10.1016/j.jclinepi.2019.12.011