Why assess study quality?
Low methodological quality can affect internal validity and introduce bias into the results of primary studies. Internal validity refers to the extent to which study results reflect the true cause-effect of an intervention. Different types of bias can influence internal validity (e.g. selection, performance, detection, and attrition biases).
Bias in primary studies can lead to an over- or under-estimation of the true intervention effect in both primary studies and systematic reviews. It is important to consider the implications of study quality and validity for interpreting the results from your systematic review and it is often a good idea to incorporate a quality assessment section into your final report.
Study quality characteristics which have been shown to impact the results of preclinical studies include whether animals were randomised to control or treatment groups, and if researchers were blinded to animal group when assessing outcomes.
Use a Risk of Bias (RoB) or quality assessment tool to help you evaluate study quality. Tools that have been developed to assess bias and quality in preclinical studies include the CAMARADES checklist, and the SYRCLE RoB tool.
References & Resources:
Hooijmans et al (2014) SYRCLE’s risk of bias tool for animal studies
Sena et al (2014) Systematic Reviews and Meta-Analysis of Preclinical Studies: Why Perform Them and How to Appraise Them Critically
Krauth et al (2013) Instruments for Assessing Risk of Bias and Other Methodological Criteria of Published Animal Studies: A Systematic Review
Macleod et al (2004) Pooling of Animal Experimental Data Reveals Influence of Study Design and Publication Bias
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