Cochrane Risk Of Bias Tool For Non-Randomized Studies
Like many others, our position is that, with very few exceptions, cause and effect conclusions regarding therapeutic interventions can only be drawn when valid RCT data exists. However, there
Cochrane Risk Of Bias Tool For Non-Randomized Studies
Like many others, our position is that, with very few exceptions, cause and effect conclusions regarding therapeutic interventions can only be drawn when valid RCT data exists. However, there are uses for observational studies which may be used to answer additional questions, and non-randomized studies (NRS) are often included in systematic reviews.
In September 2014, Cochrane published a tool for assessing bias in NRS for systematic review authors. It may be of interest to our colleagues. The tool is called ACROBAT-NRSI (“A Cochrane Risk Of Bias Assessment Tool for Non-Randomized Studies”) and is designed to assist with evaluating the risk of bias (RoB) in the results of NRS that compare the health effects of two or more interventions.
The tool focuses on internal validity. It covers seven domains through which bias might be introduced into a NRS. The domains provide a framework for considering any type of NRS, and are summarized in the table below, and many of the biases listed here are described and explanations of how they may cause bias are presented in the full document, and you can see our rough summary here: http://www.delfini.org/delfiniClick_Observations.htm#robtable
Response options for each bias include: low risk of bias; moderate risk of bias; serious risk of bias; critical risk of bias; and no information on which to base a judgment.
Details are available in the full document which can be downloaded at—https://sites.google.com/site/riskofbiastool/
We again point out that non-randomized studies often report seriously misleading