Liu 2013.

Methods	RCT, parallel design, single‐centre
Participants	Total number of randomized participants: 120 Inclusion criteria People with aMCI, history of spinal surgery, ASA I to II, aged 65 to 75 years Exclusion criteria History of general anaesthetic exposure or surgery Neurological diseases that may affect cognitive function (e.g. subdural haematoma, vascular dementia, frontotemporal dementia) Hypothyroidism Alcoholic dementia Vitamin B12 deficiency Encephalitis Cerebral infarction Brain tumour Insufficient education to complete the tests Type of surgery: spinal surgery Baseline characteristics TIVA group Age, mean (SD): 69.33 (± 2.90) years Gender, M/F: 24/28 ASA grade: all ASA I to II Inhalational maintenance group Age, mean (SD): 69.56 (± 2.99) years Gender, M/F: 27/28 ASA grade: all ASA I to II Country: China Setting: hospital
Interventions	TIVA group Participants: n = 60; 8 losses (reasons reported overall, not by group, to include: 'lost to follow‐up', death, other surgeries before 2‐year follow‐up time point); 52 analysed Induction details: midazolam 0.05 mg/kg, sufentanil 0.5 µg/kg, vecuronium 0.5 µg/kg, propofol 1.0 mg/kg Maintenance details: propofol 4 mg/kg/hour to 6 mg/kg/hour continuously, intermittent vecuronium 0.5 mg/kg. To maintain BIS 40 to 50 Other information: during surgery, patients given lactated Ringer's solution and hetastarch. Continuous infusion of sufentanil 0.6 µg/kg/hour, tropisetron 6 µg/kg/hour, single bolus of sufentanil 0.015 µg/kg and tropisetron 1.5 µg/kg over a 15‐minute interval for postoperative pain relief Inhalational maintenance group Participants: n = 60; 5 losses (reasons reported overall, not by group, to include: 'lost to follow‐up', death, other surgeries before 2‐year follow‐up time point); 55 analysed Induction details: midazolam 0.05 mg/kg, sufentanil 0.5 µg/kg, vecuronium 0.5 µg/kg, propofol 1.0 mg/kg Maintenance details: sevoflurane 2% to 3 % in pure O2. Adjusted to maintain BIS 40 to 50 Other information: fluids and analgesic management etc. same as TIVA group
Outcomes	Progression of aMCI. Measured at follow‐up of 2 years
Notes	Funding/declarations of interest: supported by the Department of Anesthesiology, Beijing Military General Hospital. The authors have no financial or other conflicts of interest to disclose Study dates: January 2007 to January 2009 Note: study has 3 arms: propofol vs sevoflurane vs lidocaine epidural. We have not included data for the lidocaine comparison arm
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Use of computer‐generated randomization
Allocation concealment (selection bias)	Unclear risk	No details
Blinding of participants and personnel (performance bias) All outcomes	High risk	Not feasible to blind anaesthetists to intervention groups
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Only review outcome of interest is mortality. Blinding of assessors is not described but lack of blinding is unlikely to influence mortality data
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	High number of losses, which are reported with reasons. We have used this as data for mortality outcome
Selective reporting (reporting bias)	Unclear risk	Study authors do not report clinical trials registration. It is not feasible to assess risk of selective outcome reporting
Other bias	Low risk	No other sources of bias identified