Review of Bias In Diabetes Randomized Controlled Trials

Healthcare professionals must evaluate the internal validity of randomized controlled trials (RCTs) as a first step in the process of considering the application of clinical findings (results) for particular patients. Bias has been repeatedly shown to increase the likelihood of distorted study results, frequently favoring the intervention.

Readers may be interested in a new systematic review of diabetes RCTs. Risk of bias (low, unclear or high) was assessed in 142 trials using the Cochrane Risk of Bias Tool.  Overall, 69 trials (49%) had at least one out of seven domains with high risk of bias. Inadequate reporting frequently hampered the risk of bias assessment: the method of producing the allocation sequence was unclear in 82 trials (58%) and allocation concealment was unclear in 78 trials (55%). There were no significant reductions in the proportion of studies at high risk of bias over time nor in the adequacy of reporting of risk of bias domains. The authors conclude that these trials have serious limitations that put the findings in question and therefore inhibit evidence-based quality improvement (QI). There is a need to limit the potential for bias when conducting QI trials and improve the quality of reporting of QI trials so that stakeholders have adequate evidence for implementation. The entire freely-available study is available at—

http://bmjopen.bmj.com/content/3/4/e002727.long

Ivers NM, Tricco AC, Taljaard M, Halperin I, Turner L, Moher D, Grimshaw JM. Quality improvement needed in quality improvement randomised trials: systematic review of interventions to improve care in diabetes. BMJ Open. 2013 Apr 9;3(4). doi:pii: e002727. 10.1136/bmjopen-2013-002727. Print 2013. PubMed PMID: 23576000.