Thirty RCTs were included in the review (total number of participants was not reported). Fourteen trials were deemed to be of high quality. The authors stated that some of the included RCTs had small sample sizes (as low as 12 participants).
Anxiety: Eight of 14 RCTs, and five of the six of high quality RCTs, found a beneficial effect of midazolam with respect to separation anxiety. Seventeen of 24 RCTs, and all 11 high quality RCTs, found a beneficial effect of midazolam with respect to induction anxiety.
Awaking emergence delirium: Two of eight RCTs, but none of the five high quality RCTs, found a beneficial effect of midazolam with respect to awakening emergence delirium. Seven of 18 RCTs, and two of the eight high quality RCTs, found a beneficial effect of midazolam on emergence.
Recovery time: Six of 21 RCTs, and one of the nine high quality RCTs, found a beneficial effect of midazolam on discharge from the post-anaesthesia care unit or the institution with respect to recovery time.
Long-term behaviour: Up to two weeks post-operatively, three of six RCTs, and one of the three high quality RCTs, found a beneficial effect of midazolam with respect to long-term behaviour, although the high quality RCT showed a beneficial effect up to one week only. Another RCT found a detrimental effect of midazolam on behaviour.
Dose and timing: A dose of 0.5 mg/kg was required to produce consistent reduction in preoperative anxiety in children less than 12 years. The optimal timing could not be determined from the studies included in the review.