The Risk of Bias in Iranian Randomized Controlled Trials Included in Cochrane Reviews

Abstract

AbstractBackgroundRandomised controlled trials (RCT) provide the highest level of evidence among interventional studies. However, RCTs may be susceptible to the risk of bias (RoB). Therefore, systematic reviews appraise the RoB in all included studies in a review by using evaluation tools. This study aimed to describe the main characteristics of RCTs conducted in Iran and included in Cochrane Reviews (CRs) by focusing on their RoB.MethodsWe searched “Iran” by selecting the “Search All Text” field and “Review” in the Cochrane Database of systematic Review within Ovid. We retrieved CRs that included Iranian controlled trials. We selected trials only if they had involved human subjects, described as a controlled clinical trial, included in CRs and therefore the review authors assessed their RoBs. The characteristics of trials have been extracted by looking at the table “Characteristics of included studies” in each CRs as well as the relevant papers. To addressing RoB, we collected the judgment of the review authors according to the table of RoB assessments in CRs.ResultsThere were 1166 Iranian RCTs included in 571 CRs. From all these studies, 44.9% were at low RoB for random sequence generation, 20.8% for allocation concealment, 32.3% for blinding of participants/personnel, 36.5% for blinding of outcome assessors, 56.3% for incomplete outcome data, 41.3% selective reporting, and 53.8% for other bias.ConclusionRoB was mainly high or unclear in Iranian RCTs. Special attention must be paid to methodological quality of RCTs in Iran accordingly.