Document Detail

Do Unblinded Assessors Bias Muscle Strength Outcomes in Randomized Controlled Trials of Progressive Resistance Strength Training in Older Adults?
MedLine Citation:
PMID:  21173683     Owner:  NLM     Status:  Publisher    
OBJECTIVE:: Knowledge of treatment assignment and failing to analyze results by randomized treatment groups-an intention-to-treat analysis-may cause bias in the treatment effect estimate in randomized controlled trials. This study was undertaken to determine the difference in lower limb muscle strength measured by blinded vs. by unblinded outcome assessors in 73 progressive resistance strength training trials conducted in older adults. DESIGN:: Retrospective analysis of randomized controlled trials published before 2007. RESULTS:: Meta-regression analyses showed that trials that used blinded assessors (n = 18) tend to report smaller effect sizes than do those that used unblinded assessors (n = 55), with a difference of -0.80 (95% confidence interval, -1.35 to -0.25). This result still holds even after adjusting for the use of an intention-to-treat analysis, with an adjusted difference of -0.65 (95% confidence interval, -1.26 to -0.04). The reported effects were exaggerated in trials that used unblinded assessors. CONCLUSIONS:: This study suggests that assessor blinding is important and is a safeguard to the internal validity of exercise trials in older adults.
Chiung-Ju Liu; Michael Lavalley; Nancy K Latham
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2010-12-3
Journal Detail:
Title:  American journal of physical medicine & rehabilitation / Association of Academic Physiatrists     Volume:  -     ISSN:  1537-7385     ISO Abbreviation:  -     Publication Date:  2010 Dec 
Date Detail:
Created Date:  2010-12-21     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8803677     Medline TA:  Am J Phys Med Rehabil     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
From the Department of Occupational Therapy, School of Health and Rehabilitation Sciences, Indiana University at Indianapolis (IUPUI) (C-JL); and Department of Biostatistics (MLV) and Health and Disability Research Institute (NKL), Boston University School of Public Health, Massachusetts.
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