Kerssens 2009.

Methods	Study design: randomized parallel groups Study dates: Quote: "January 2004 to February 2007" (email bias survey, see notes)
Participants	Country: USA Sex: both Age: 61.2, 63.9 Procedure: joint replacement surgery Study size: 167 enrolled, 128 completed study
Interventions	Randomized portion of anaesthetic: volatile agent types: ADM: BIS 50 to 60 vs SCPs Intervention 1: BIS monitor used to guide anaesthetic, maintained between 50 to 60, N = 67 Intervention 2: BIS not seen, standard clinical signs to guide anaesthetic, N = 61
Outcomes	Primary outcomes: effect of BIS‐guided anaesthesia vs SCP on memory recognition function Secondary outcome: awareness/wakefulness as defined using an awareness classification system (see Table 1): class 1 Quote: "When interviewed postoperatively, three patients (2.3%) reported recall of the time period between falling asleep and waking up from anaesthesia" Comment: 2 patients were in BIS group and 1 in SCP group. There was evidence of implicit memory in the BIS guided group compared to the SCP group.
Notes	Non‐randomized portion of anaesthetic: parts of volatile agent: N2O no/narcotics/hypnotics bolus MCI/muscle relaxants induction yes/maintenance PRN Anaesthesia induction: propofol 2 mg/kg + fentanyl 3 µg/kg + vecuronium bromide (0.1 mg/kg) tracheal intubation, additional doses as necessary; maintenance: sevoflurane in oxygen using standard ventilation parameters + fentanyl 50 µg to 100 µg + esmolol 0.5 mg/kg + phenylephrine 100 µg + fentanyl 50 µg to 100 µg/kg as needed. Physiologic parameters recorded: BIS, end‐tidal gas concentrations (but actual ET data reported) (every 5 s) and vital signs (every 3 min) Time of outcome determination: 6 h postoperative Method of outcome determination: interview questions Comment: see Dryad topics BIS and implicit memory vs SCPs and dreams Survey response: 10 March 2011, Chantal Kerssens ckerssens@simpleC.com Author sent characteristics and ROB tables for comment 7 December 2013: ckerssens@simpleC.com
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "Patients were randomly assigned to one of two anaesthetic management groups using a computer‐generated list linking subject study numbers to group assignment"
Allocation concealment (selection bias)	Unclear risk	Comment: no information provided
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Comment: no information provided
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: assessor: "Outcome assessors were blinded to study group allocation and tested patients postoperatively for recall and recognition memory. Recall was assessed approximately 6 h after surgery with five questions"
Incomplete outcome data (attrition bias) All outcomes	Low risk	Quote: "Numbers are reported in the paper. The ratios and reasons for exclusion/attrition were comparable between groups." (email bias survey, see notes) Author sent characteristics and ROB tables for comment 7 December 2013: ckerssens@simpleC.com
Selective reporting (reporting bias)	Low risk	Quote: "True" (email bias survey, see notes) Comment: awareness outcome part of inclusion criteria
Other bias	Low risk	Quote: "Yes. We stopped enrolment/testing when the main study ‐unrelated to memory function ‐ reached it's target enrolment number." (email bias survey, see notes)