Study	Reason for exclusion
Akcali 2008	The study was not a RCT (historical control)
Arnold 2007	The study was not a RCT
Ballard 2012	The study was a RCT comparing active anaesthetic monitoring (bispectral index and cerebral oxygen saturation) with a control condition on the incidence of postoperative cognitive decline in older adults undergoing surgery. The outcome (postoperative cognitive decline ) was not in the scope of this review)
Berti 2000	The study was a RCT comparing three groups (i.e. subarachnoid anaesthesia versus general anaesthesia with bispectral index versus general anaesthesia without bispectral index) but did not provide data on the relevant outcomes
Burrow 2001	The study was not a RCT
Caba 2003	Outcome was not relevant (the need for postoperative analgesia)
Guignard 2001	The study was not a RCT (historical control)
Johansen 2000	The study was not a RCT. It was an open, observational trial with retrospective analysis
Lehmann 2003	This study was a RCT but compared 2 levels of BIS‐guided anaesthesia. Its publication has been withdrawn by a journal
Leslie 2005b	The study was a substudy of the B‐Aware randomized controlled trial (Myles 2004) and focused on dreaming during anaesthesia (PMID: 15710008)
Lindholm 2008	The study investigated how increasing experience from BIS in clinical practice affect the hypnotic level, drug consumption, as well as subjective opinions on this monitoring. Therefore, it did not fulfil the objective of our review
Mayer 2007	Its publication has been withdrawn by a journal
Pavlin 2001	The study was a RCT but the randomization was different from the other studies. It allocated healthcare providers to use or not use BIS for guiding doses of anaesthetics. Therefore, the study design did not fulfil the inclusion criteria of the study selection in terms of randomization process
Pavlin 2005	The study was a RCT but the randomization was different from the other studies. It allocated healthcare providers to use or not use BIS for guiding doses of anaesthetics. Therefore, the study design did not fulfil the inclusion criteria of the study selection in terms of randomization process
Schulz 2007	The study was not a RCT
Sebel 1997	It was a multicentre RCT to evaluate the real‐time utility of BIS in predicting movement response incision. Hence, it did not fulfil the objective of this review
Song 1998	This study was a RCT but did not use BIS guiding doses of anaesthetics but used it as a tool to measure the effect of two anaesthetics
Vedtofte 2007	The study was a RCT but the randomization was different from the other studies. It allocated healthcare providers to use or not use BIS for guiding doses of anaesthetics. Therefore, the study design did not fulfil the inclusion criteria of the study selection in terms of randomization process
Yli‐Hankala 1999	This study was an RCT but was excluded as it randomly allocated participant into two groups based on the anaesthetic use (propofol versus sevoflurane). The comparison group was an historical control group

RCT = randomized controlled trial BIS = bispectral index