3.2. Risk of biasThe risk of bias was high in all of the included trials (Fig. 2). Onlyone trial was described as randomized [32], while two RCTs usedsequence generated by admission order [31,33]. The other RCT didnot report the random sequence generation method [34]. None ofthe RCTs mentioned allocation concealment or blinded outcomeassessment. Most of the included trials had a high risk of bias dueto not blinding patients and practitioners, except for one RCT [34].Drop-out cases were reported by three RCTs [31,33,34], while thelast trial did not report [32]. None of the trials had published pro-tocols and they all had an unclear risk of bias in selective outcomereporting