Clinical Studies: Systematic Review

Systematic review clinical assessment and evaluation of all studies that discusses the same clinical issue, simply its summary of outcomes of researched studies in a quantitative manner and hence it's named Meta analysis. After setting a question and searching for studies that meets the eligibility criteria and reading it very well to obtain adequate and precise results for Meta analysis detection of bias in the individual studies is an important issue to avoid inadequate results and to be sure that the data collected is confidence wise.1

So bias is critical topic and must be focused in.

In my research I am going to discuss types of bias in the individual study, the causes of that bias and how to avoid it.

What is Bias?

I can define bias

Clinician deviation toward a group of participants or selecting a special group to undergo the new intervention to obtain good results. That’s why the strength of randomization is important to prevents selection bias in allocating interventions to participants. A rule for allocating interventions to participants must be specified, based on some chance (random) process. That is called sequence generation. Many steps must be done to secure the implementation of that schedule of random assignments by preventing foreknowledge of the forthcoming allocations. The clinician must not be aware by the next patient that will be treated, this process is termed allocation concealment, and could more accurately be described as allocation sequence concealment. Thus, one suitable method for assigning interventions would be to use a simple random (and therefore unpredictable) sequence, and to conceal the upcoming allocations from those involved in enrolment into the

contamination, whereby the experimental and control interventions get ‘mixed’, for example if participants pool their drugs) and there may be sources of bias that are only found in a particular clinical setting.2

Stages for risk of bias assessment in the individual study:

1/develop a protocol

Explain how the risk of bias will be summarized to obtain low high or unclear risk of bias in the study outcome

2/pilot team and train reviewers

It's very important that two viewers to detect the risk of bias in the study and third one for any conflicts

3/Perform assessment of risk of individual study

It depends on judgment of each outcome risk of bias and categorizing the results (high low or unclear) then resolve differences between each outcome and record final result.

4/use assessment of risk of bias in synthesis of evidence That may make us need further more additional analysis.

5/report assessment of risk of bias limitation and process

Describing actions to improve risk of bias assessment