allocation concealment

allocation concealment

The process of concealing information about which patients are to be assigned to a new treatment versus those to be given a conventional therapy. It is believed that bias may be introduced in the allocation concealment process, based on the a priori belief by the investigator that one therapy is better than another.
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The items included the following 7 aspects: random sequence generation (selection bias), allocation concealment (selection bias), blinding of participants and personnel (performance bias), blinding of outcome assessment (detection bias), incomplete outcome data (attrition bias), selective reporting (reporting bias), and other bias.
However, we believe that risk-of-bias domains used in human experimental studies that have an empirical basis--including sequence generation, allocation concealment, blinding, incomplete outcome data, and selective reporting--are directly relevant to toxicological studies.
The included RCTs were of generally low methodological quality: 7 trials reported adequate randomization methods, and 2 of these reported allocation concealment.
A restricted analysis on the mortality effect of gelatin solutions in cardiac surgical patients alone or studies that had adequate allocation concealment and double-blinding was also performed.
There are important methodological issues with this study, including lack of clarity on allocation concealment and whether outcome assessment was blinded.
The conditions for internal validity of RCTs are rarely if ever satisfied by randomization, allocation concealment, double-blind administration of treatment, the handling of withdrawals and drop-outs, and the statistical tests.
RCTs with an unclear generation of the allocation sequence, allocation concealment and double blinding frequently overestimate intervention efficacy.
2003] reported a treatment effect overestimation of 54% and 53% due to lack of allocation concealment and lack of evaluator blinding, respectively.
Allocation was by block randomisation stratified by centre and time from unprotected sexual intercourse to treatment, with allocation concealment by identical opaque boxes labelled with a unique treatment number.
They provide clarification on aspects of the treatment intervention used in their high quality randomised controlled trial (RCT) (Kucera 2004), and challenge the PEDro scores that we attributed to the following items: allocation concealment, baseline comparability, and blinding.
This study was a significant undertaking and had a large national sample, but it was hampered by a lack of allocation concealment.
Quality assessment was based on the adequacy of allocation concealment, generation of allocation sequence, and blinding of study participants, investigators, and outcome assessors.
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