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Contemp Clin Trials. 2009 Jan;30(1):20-3. doi: 10.1016/j.cct.2008.08.004. Epub 2008 Aug 31.

Clinical trial variability: quality control in a randomized clinical trial.

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Canadian Memorial Chiropractic College, Toronto, Ontario, Canada.



A major issue in clinical trials in manual medicine is treatment variability. The challenge is to insure that the bounded treatment options are both representative of field practitioner behavior and consistent among research clinicians. This investigation assesses the treatment comparability of field practitioners and research clinicians, for a flexion-distraction treatment procedure, as quality control for a randomized clinical trial.


Using a series of vignettes, we studied the level of agreement of treatment protocols between field clinicians, research clinicians and a reference clinician regarding treatment location, range of motion during treatment, and number of repetitions used within the flexion-distraction protocol.


Results indicated that reliability around decision making for anticipated location of spinal treatment was highest regardless of clinician group. For the research clinicians this level of agreement was ICC=0.88. Decision-making for treatment direction was second highest, at kappa=0.64 for the research clinicians. Reliability around the number of repetitions is poor ranging from ICC=0.18 to 0.34 depending on clinician type.


Understanding the disparity in treatment protocols is of value in the construction and maintenance of quality control in an actual randomized clinical trial setting. More work was recommended in the preparation of clinical trials and the understanding of clinical decision-making because these disparate factors may dramatically impact the generalizability of clinical trial results.

[Indexed for MEDLINE]

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