Abstract
BackgroundBlinding is a cornerstone of treatment evaluation. Blinding is more difficult to obtain in trials assessing nonpharmacological treatment and frequently relies on “creative” (nonstandard) methods. The purpose of this study was to systematically describe the strategies used to obtain blinding in a sample of randomized controlled trials of nonpharmacological treatment.Methods and FindingsWe systematically searched in Medline and the Cochrane Methodology Register for randomized controlled trials (RCTs) assessing nonpharmacological treatment with blinding, published during 2004 in high-impact-factor journals. Data were extracted using a standardized extraction form. We identified 145 articles, with the method of blinding described in 123 of the reports. Methods of blinding of participants and/or health care providers and/or other caregivers concerned mainly use of sham procedures such as simulation of surgical procedures, similar attention-control interventions, or a placebo with a different mode of administration for rehabilitation or psychotherapy. Trials assessing devices reported various placebo interventions such as use of sham prosthesis, identical apparatus (e.g., identical but inactivated machine or use of activated machine with a barrier to block the treatment), or simulation of using a device. Blinding participants to the study hypothesis was also an important method of blinding. The methods reported for blinding outcome assessors relied mainly on centralized assessment of paraclinical examinations, clinical examinations (i.e., use of video, audiotape, photography), or adjudications of clinical events.ConclusionsThis study classifies blinding methods and provides a detailed description of methods that could overcome some barriers of blinding in clinical trials assessing nonpharmacological treatment, and provides information for readers assessing the quality of results of such trials.
Highlights
Bias in clinical research can be described as systematic error that can result in false treatment effect estimates [1]
This study classifies blinding methods and provides a detailed description of methods that could overcome some barriers of blinding in clinical trials assessing nonpharmacological treatment, and provides information for readers assessing the quality of results of such trials
Domain of Interest and Defining Nonpharmacological treatment (NPT) We assessed the reporting of blinding and the method of blinding participants, health care providers, and outcome assessors
Summary
Bias in clinical research can be described as systematic error that can result in false treatment effect estimates [1]. Blinding of outcome assessors minimizes the risk of detection bias (i.e., observer, ascertainment, assessment bias) This type of bias occurs if participant assignment influences the process of outcome assessment [10]. The purpose of this study was to systematically describe the strategies used to obtain blinding in a sample of randomized controlled trials of nonpharmacological treatment. An additional technique used is ‘‘blinding,’’ which involves taking steps to prevent patients, doctors, or other people involved in the trial (e.g., those recording measurements) from finding out which patients have received which treatment. Done, blinding should make sure the results of a trial are more accurate This is because in an unblinded study, participants may respond better if they know they have received a promising new treatment (or worse if they only got a placebo or an old drug). Blinding is not a simple, single step; the people carrying out the trial often have to set up a variety of different procedures
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