Anaesthetic depth and complications after major surgery: an international, randomised controlled trial

Australian and New Zealand College of Anaesthetists Clinical Trials Network, Balanced Anaesthesia Study Group

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

Background: An association between increasing anaesthetic depth and decreased postoperative survival has been shown in observational studies; however, evidence from randomised controlled trials is lacking. Our aim was to compare all-cause 1-year mortality in older patients having major surgery and randomly assigned to light or deep general anaesthesia. Methods: In an international trial, we recruited patients from 73 centres in seven countries who were aged 60 years and older, with significant comorbidity, having surgery with expected duration of more than 2 h, and an anticipated hospital stay of at least 2 days. We randomly assigned patients who had increased risk of complications after major surgery to receive light general anaesthesia (bispectral index [BIS] target 50) or deep general anaesthesia (BIS target 35). Anaesthetists also nominated an appropriate range for mean arterial pressure for each patient during surgery. Patients were randomly assigned in permuted blocks by region immediately before surgery, with the patient and assessors masked to group allocation. The primary outcome was 1-year all-cause mortality. The trial is registered with the Australian New Zealand Clinical Trials Registry, ACTRN12612000632897, and is closed to accrual. Findings: Patients were enrolled between Dec 19, 2012, and Dec 12, 2017. Of the 18 026 patients screened as eligible, 6644 were enrolled, randomly assigned to treatment or control, and formed the intention-to-treat population (3316 in the BIS 50 group and 3328 in the BIS 35 group). The median BIS was 47·2 (IQR 43·7 to 50·5) in the BIS 50 group and 38·8 (36·3 to 42·4) in the BIS 35 group. Mean arterial pressure was 3·5 mm Hg (4%) higher (median 84·5 [IQR 78·0 to 91·3] and 81·0 [75·4 to 87·6], respectively) and volatile anaesthetic use was 0·26 minimum alveolar concentration (30%) lower (0·62 [0·52 to 0·73] and 0·88 [0·74 to 1·04], respectively) in the BIS 50 than the BIS 35 group. 1-year mortality was 6·5% (212 patients) in the BIS 50 group and 7·2% (238 patients) in the BIS 35 group (hazard ratio 0·88, 95% CI 0·73 to 1·07, absolute risk reduction 0·8%, 95% CI −0·5 to 2·0). Grade 3 adverse events occurred in 954 (29%) patients in the BIS 50 group and 909 (27%) patients in the BIS 35 group; and grade 4 adverse events in 265 (8%) and 259 (8%) patients, respectively. The most commonly reported adverse events were infections, vascular disorders, cardiac disorders, and neoplasms. Interpretation: Among patients at increased risk of complications after major surgery, light general anaesthesia was not associated with lower 1-year mortality than deep general anaesthesia. Our trial defines a broad range of anaesthetic depth over which anaesthesia may be safely delivered when titrating volatile anaesthetic concentrations using a processed electroencephalographic monitor. Funding: Health Research Council of New Zealand; National Health and Medical Research Council, Australia; Research Grant Council of Hong Kong; National Institute for Health and Research, UK; and National Institutes of Health, USA.

Original languageEnglish
Pages (from-to)1907-1914
Number of pages8
JournalThe Lancet
Volume394
Issue number10212
DOIs
Publication statusPublished - 23 Nov 2019

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Anesthetics
Randomized Controlled Trials
General Anesthesia
Mortality
National Institutes of Health (U.S.)
New Zealand
Arterial Pressure
Research
Numbers Needed To Treat
Heart Neoplasms
Health
Hong Kong
Observational Studies
Blood Vessels
Registries
Biomedical Research
Comorbidity
Length of Stay
Anesthesia
Clinical Trials

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Australian and New Zealand College of Anaesthetists Clinical Trials Network, & Balanced Anaesthesia Study Group (2019). Anaesthetic depth and complications after major surgery: an international, randomised controlled trial. The Lancet, 394(10212), 1907-1914. https://doi.org/10.1016/S0140-6736(19)32315-3
Australian and New Zealand College of Anaesthetists Clinical Trials Network ; Balanced Anaesthesia Study Group. / Anaesthetic depth and complications after major surgery : an international, randomised controlled trial. In: The Lancet. 2019 ; Vol. 394, No. 10212. pp. 1907-1914.
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title = "Anaesthetic depth and complications after major surgery: an international, randomised controlled trial",
abstract = "Background: An association between increasing anaesthetic depth and decreased postoperative survival has been shown in observational studies; however, evidence from randomised controlled trials is lacking. Our aim was to compare all-cause 1-year mortality in older patients having major surgery and randomly assigned to light or deep general anaesthesia. Methods: In an international trial, we recruited patients from 73 centres in seven countries who were aged 60 years and older, with significant comorbidity, having surgery with expected duration of more than 2 h, and an anticipated hospital stay of at least 2 days. We randomly assigned patients who had increased risk of complications after major surgery to receive light general anaesthesia (bispectral index [BIS] target 50) or deep general anaesthesia (BIS target 35). Anaesthetists also nominated an appropriate range for mean arterial pressure for each patient during surgery. Patients were randomly assigned in permuted blocks by region immediately before surgery, with the patient and assessors masked to group allocation. The primary outcome was 1-year all-cause mortality. The trial is registered with the Australian New Zealand Clinical Trials Registry, ACTRN12612000632897, and is closed to accrual. Findings: Patients were enrolled between Dec 19, 2012, and Dec 12, 2017. Of the 18 026 patients screened as eligible, 6644 were enrolled, randomly assigned to treatment or control, and formed the intention-to-treat population (3316 in the BIS 50 group and 3328 in the BIS 35 group). The median BIS was 47·2 (IQR 43·7 to 50·5) in the BIS 50 group and 38·8 (36·3 to 42·4) in the BIS 35 group. Mean arterial pressure was 3·5 mm Hg (4{\%}) higher (median 84·5 [IQR 78·0 to 91·3] and 81·0 [75·4 to 87·6], respectively) and volatile anaesthetic use was 0·26 minimum alveolar concentration (30{\%}) lower (0·62 [0·52 to 0·73] and 0·88 [0·74 to 1·04], respectively) in the BIS 50 than the BIS 35 group. 1-year mortality was 6·5{\%} (212 patients) in the BIS 50 group and 7·2{\%} (238 patients) in the BIS 35 group (hazard ratio 0·88, 95{\%} CI 0·73 to 1·07, absolute risk reduction 0·8{\%}, 95{\%} CI −0·5 to 2·0). Grade 3 adverse events occurred in 954 (29{\%}) patients in the BIS 50 group and 909 (27{\%}) patients in the BIS 35 group; and grade 4 adverse events in 265 (8{\%}) and 259 (8{\%}) patients, respectively. The most commonly reported adverse events were infections, vascular disorders, cardiac disorders, and neoplasms. Interpretation: Among patients at increased risk of complications after major surgery, light general anaesthesia was not associated with lower 1-year mortality than deep general anaesthesia. Our trial defines a broad range of anaesthetic depth over which anaesthesia may be safely delivered when titrating volatile anaesthetic concentrations using a processed electroencephalographic monitor. Funding: Health Research Council of New Zealand; National Health and Medical Research Council, Australia; Research Grant Council of Hong Kong; National Institute for Health and Research, UK; and National Institutes of Health, USA.",
author = "{Australian and New Zealand College of Anaesthetists Clinical Trials Network} and {Balanced Anaesthesia Study Group} and Short, {Timothy G.} and Douglas Campbell and Christopher Frampton and Chan, {Matthew T.V.} and Myles, {Paul S.} and Corcoran, {Tom{\'a}s B.} and Sessler, {Daniel I.} and Mills, {Gary H.} and Cata, {Juan P.} and Thomas Painter and Kelly Byrne and Ruquan Han and Chu, {Mandy H.M.} and McAllister, {Davina J.} and Kate Leslie and M. Shulman and S. Wallace and C. Farrington and W. Gallagher and A. Ditoro and P. Peyton and S. Baulch and A. Dalyell and S. Sidiropoulos and J. Reynolds and J. Rowley and N. Tan and D. McCallum and E. O'Loughlin and S. Wong and K. Owen and Sim, {I. K.} and L. Glazov and P. Coutts and M. Pushpanathan and V. Findlay and M. Paech and D. Cavill and A. Chuan and L. Pope and J. Lucas and B. Robinson and A. Millard and S. Allen and M. Allen and S. McKeown and P. Sivalingam and T. Wilkes and C. Jowett and A. Kearney and M. Bennett and Favero, {J. P.} and S. Sawhney and K. Drummond and S. Osborn and A. Wing and J. Taylor and M. Edwards and H. Reynolds and C. Town and N. Terblanche and M. Challis and R. Seale and K. Button and R. Cotter and M. Stewart and N. Zingerle and S. Hannon and D. Middleton and C. Edgley and S. March and T. McCulloch and G. Wong and S. Jeong and K. Connell and K. Kramer and G. Henderson and V. Ward and Y. Buller and N. Hird and D. Scott and L. Evered and G. Snyder and B. Silbert and P. Corcoran and E. Fitzgerald and S. Said and A. Watson and D. Baby and S. Bolsin and A. Marriott and K. Ives and Wakefeld, {B. J.} and A. Jeffreys and S. Bates and R. Halliwell and D. Elliott and L. Cope and R. Paranthoiene and P. Peng and X. Liu and X. Zhou and X. Jin and H. Liu and L. An and W. Cui and L. Zhang and B. Jia and J. Fang and E. Koo and E. Lo and B. Fung and M. Tsang and L. Lam and E. Pang and V. Lau and G. Choi and R. Kwok and K. Yau and B. Cheng and C. Lam and E. Lee and D. Buggy and H. Keane and K. Byrne and C. Connolly and M. Ali and A. Cervantes and K. Kumar and S. Dandy and L. Ritchie and R. Kennedy and M. McKellow and C. Read and D. France and H. Truong and C. Chapman and S. Walker and S. Olliff and H. Houston and M. Scott and I. Minchin and A. Moniwa and J. McAlpine and M. Chaddock and L. Gray and C. Czepanski and S. Vinish and U. Buehner and E. Williams and C. Zhou and L. Goodman and J. Bermaat and G. Mans and A. Garden and R. Franks and J. Deiterle and J. Barrett and S. Roubos and {van Lier}, F. and S. Verbrugge and C. Kalkman and J. Dieleman and J. Verdam-Veldkamp and {van Kampen}, A. and A. Pai and A. Sevillano and J. Yeung and T. Melody and K. Atterbury and M. Hough and S. Dukes and S. Williams and Z. Milan and G. Kunst and K. Bhatia and W. MacNab and E. Weaver and R. Moulding and P. Doble and P. Klepsch and J. Self and T. Howes and B. Rees and B. Faulkner and J. Blackburn and N. Crombie and L. Cooper and A. Nair and G. Bell and R. Longfellow and C. Nicholas and T. Garratt and M. Pollard and G. Brown and G. Morrison and A. Lang and H. Dawson and M. MacDonald and T. Martin and E. Niebrzegowska and P. Dias and {Rao Baikady}, R. and S. Jhanji and N. Siddaiah and L. Bird and R. Mittal and P. Nalawaya and J. Sonksen and R. Gidda and I. Wrench and N. Craw and L. Pippard and S. Davies and M. Wright and M. Turan and K. Maheshwari and B. Cohen and W. Saasouh and P. Singh and S. Govindarajan and E. Cuko and F. Marcano and R. Babazade and S. Leung and S. Raza and E. Reville and C. Hanline and S. Ayad and M. Buttar and Z. Akhtar and A. Niazi and P. Saha and A. Morris and C. Lokhande and M. Hassan and H. Honar and G. Bairacharya and J. Saxon and D. Chelnick and R. Carlson and J. Ruiz and J. Wilks and W. Williams and L. Dangler and I. Ifeanyi-Pillette and J. Suarez and G. Yang and M. Mehta and F. Cooke",
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month = "11",
day = "23",
doi = "10.1016/S0140-6736(19)32315-3",
language = "English",
volume = "394",
pages = "1907--1914",
journal = "Lancet",
issn = "0140-6736",
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}

Australian and New Zealand College of Anaesthetists Clinical Trials Network & Balanced Anaesthesia Study Group 2019, 'Anaesthetic depth and complications after major surgery: an international, randomised controlled trial' The Lancet, vol. 394, no. 10212, pp. 1907-1914. https://doi.org/10.1016/S0140-6736(19)32315-3

Anaesthetic depth and complications after major surgery : an international, randomised controlled trial. / Australian and New Zealand College of Anaesthetists Clinical Trials Network; Balanced Anaesthesia Study Group.

In: The Lancet, Vol. 394, No. 10212, 23.11.2019, p. 1907-1914.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Anaesthetic depth and complications after major surgery

T2 - an international, randomised controlled trial

AU - Australian and New Zealand College of Anaesthetists Clinical Trials Network

AU - Balanced Anaesthesia Study Group

AU - Short, Timothy G.

AU - Campbell, Douglas

AU - Frampton, Christopher

AU - Chan, Matthew T.V.

AU - Myles, Paul S.

AU - Corcoran, Tomás B.

AU - Sessler, Daniel I.

AU - Mills, Gary H.

AU - Cata, Juan P.

AU - Painter, Thomas

AU - Byrne, Kelly

AU - Han, Ruquan

AU - Chu, Mandy H.M.

AU - McAllister, Davina J.

AU - Leslie, Kate

AU - Shulman, M.

AU - Wallace, S.

AU - Farrington, C.

AU - Gallagher, W.

AU - Ditoro, A.

AU - Peyton, P.

AU - Baulch, S.

AU - Dalyell, A.

AU - Sidiropoulos, S.

AU - Reynolds, J.

AU - Rowley, J.

AU - Tan, N.

AU - McCallum, D.

AU - O'Loughlin, E.

AU - Wong, S.

AU - Owen, K.

AU - Sim, I. K.

AU - Glazov, L.

AU - Coutts, P.

AU - Pushpanathan, M.

AU - Findlay, V.

AU - Paech, M.

AU - Cavill, D.

AU - Chuan, A.

AU - Pope, L.

AU - Lucas, J.

AU - Robinson, B.

AU - Millard, A.

AU - Allen, S.

AU - Allen, M.

AU - McKeown, S.

AU - Sivalingam, P.

AU - Wilkes, T.

AU - Jowett, C.

AU - Kearney, A.

AU - Bennett, M.

AU - Favero, J. P.

AU - Sawhney, S.

AU - Drummond, K.

AU - Osborn, S.

AU - Wing, A.

AU - Taylor, J.

AU - Edwards, M.

AU - Reynolds, H.

AU - Town, C.

AU - Terblanche, N.

AU - Challis, M.

AU - Seale, R.

AU - Button, K.

AU - Cotter, R.

AU - Stewart, M.

AU - Zingerle, N.

AU - Hannon, S.

AU - Middleton, D.

AU - Edgley, C.

AU - March, S.

AU - McCulloch, T.

AU - Wong, G.

AU - Jeong, S.

AU - Connell, K.

AU - Kramer, K.

AU - Henderson, G.

AU - Ward, V.

AU - Buller, Y.

AU - Hird, N.

AU - Scott, D.

AU - Evered, L.

AU - Snyder, G.

AU - Silbert, B.

AU - Corcoran, P.

AU - Fitzgerald, E.

AU - Said, S.

AU - Watson, A.

AU - Baby, D.

AU - Bolsin, S.

AU - Marriott, A.

AU - Ives, K.

AU - Wakefeld, B. J.

AU - Jeffreys, A.

AU - Bates, S.

AU - Halliwell, R.

AU - Elliott, D.

AU - Cope, L.

AU - Paranthoiene, R.

AU - Peng, P.

AU - Liu, X.

AU - Zhou, X.

AU - Jin, X.

AU - Liu, H.

AU - An, L.

AU - Cui, W.

AU - Zhang, L.

AU - Jia, B.

AU - Fang, J.

AU - Koo, E.

AU - Lo, E.

AU - Fung, B.

AU - Tsang, M.

AU - Lam, L.

AU - Pang, E.

AU - Lau, V.

AU - Choi, G.

AU - Kwok, R.

AU - Yau, K.

AU - Cheng, B.

AU - Lam, C.

AU - Lee, E.

AU - Buggy, D.

AU - Keane, H.

AU - Byrne, K.

AU - Connolly, C.

AU - Ali, M.

AU - Cervantes, A.

AU - Kumar, K.

AU - Dandy, S.

AU - Ritchie, L.

AU - Kennedy, R.

AU - McKellow, M.

AU - Read, C.

AU - France, D.

AU - Truong, H.

AU - Chapman, C.

AU - Walker, S.

AU - Olliff, S.

AU - Houston, H.

AU - Scott, M.

AU - Minchin, I.

AU - Moniwa, A.

AU - McAlpine, J.

AU - Chaddock, M.

AU - Gray, L.

AU - Czepanski, C.

AU - Vinish, S.

AU - Buehner, U.

AU - Williams, E.

AU - Zhou, C.

AU - Goodman, L.

AU - Bermaat, J.

AU - Mans, G.

AU - Garden, A.

AU - Franks, R.

AU - Deiterle, J.

AU - Barrett, J.

AU - Roubos, S.

AU - van Lier, F.

AU - Verbrugge, S.

AU - Kalkman, C.

AU - Dieleman, J.

AU - Verdam-Veldkamp, J.

AU - van Kampen, A.

AU - Pai, A.

AU - Sevillano, A.

AU - Yeung, J.

AU - Melody, T.

AU - Atterbury, K.

AU - Hough, M.

AU - Dukes, S.

AU - Williams, S.

AU - Milan, Z.

AU - Kunst, G.

AU - Bhatia, K.

AU - MacNab, W.

AU - Weaver, E.

AU - Moulding, R.

AU - Doble, P.

AU - Klepsch, P.

AU - Self, J.

AU - Howes, T.

AU - Rees, B.

AU - Faulkner, B.

AU - Blackburn, J.

AU - Crombie, N.

AU - Cooper, L.

AU - Nair, A.

AU - Bell, G.

AU - Longfellow, R.

AU - Nicholas, C.

AU - Garratt, T.

AU - Pollard, M.

AU - Brown, G.

AU - Morrison, G.

AU - Lang, A.

AU - Dawson, H.

AU - MacDonald, M.

AU - Martin, T.

AU - Niebrzegowska, E.

AU - Dias, P.

AU - Rao Baikady, R.

AU - Jhanji, S.

AU - Siddaiah, N.

AU - Bird, L.

AU - Mittal, R.

AU - Nalawaya, P.

AU - Sonksen, J.

AU - Gidda, R.

AU - Wrench, I.

AU - Craw, N.

AU - Pippard, L.

AU - Davies, S.

AU - Wright, M.

AU - Turan, M.

AU - Maheshwari, K.

AU - Cohen, B.

AU - Saasouh, W.

AU - Singh, P.

AU - Govindarajan, S.

AU - Cuko, E.

AU - Marcano, F.

AU - Babazade, R.

AU - Leung, S.

AU - Raza, S.

AU - Reville, E.

AU - Hanline, C.

AU - Ayad, S.

AU - Buttar, M.

AU - Akhtar, Z.

AU - Niazi, A.

AU - Saha, P.

AU - Morris, A.

AU - Lokhande, C.

AU - Hassan, M.

AU - Honar, H.

AU - Bairacharya, G.

AU - Saxon, J.

AU - Chelnick, D.

AU - Carlson, R.

AU - Ruiz, J.

AU - Wilks, J.

AU - Williams, W.

AU - Dangler, L.

AU - Ifeanyi-Pillette, I.

AU - Suarez, J.

AU - Yang, G.

AU - Mehta, M.

AU - Cooke, F.

PY - 2019/11/23

Y1 - 2019/11/23

N2 - Background: An association between increasing anaesthetic depth and decreased postoperative survival has been shown in observational studies; however, evidence from randomised controlled trials is lacking. Our aim was to compare all-cause 1-year mortality in older patients having major surgery and randomly assigned to light or deep general anaesthesia. Methods: In an international trial, we recruited patients from 73 centres in seven countries who were aged 60 years and older, with significant comorbidity, having surgery with expected duration of more than 2 h, and an anticipated hospital stay of at least 2 days. We randomly assigned patients who had increased risk of complications after major surgery to receive light general anaesthesia (bispectral index [BIS] target 50) or deep general anaesthesia (BIS target 35). Anaesthetists also nominated an appropriate range for mean arterial pressure for each patient during surgery. Patients were randomly assigned in permuted blocks by region immediately before surgery, with the patient and assessors masked to group allocation. The primary outcome was 1-year all-cause mortality. The trial is registered with the Australian New Zealand Clinical Trials Registry, ACTRN12612000632897, and is closed to accrual. Findings: Patients were enrolled between Dec 19, 2012, and Dec 12, 2017. Of the 18 026 patients screened as eligible, 6644 were enrolled, randomly assigned to treatment or control, and formed the intention-to-treat population (3316 in the BIS 50 group and 3328 in the BIS 35 group). The median BIS was 47·2 (IQR 43·7 to 50·5) in the BIS 50 group and 38·8 (36·3 to 42·4) in the BIS 35 group. Mean arterial pressure was 3·5 mm Hg (4%) higher (median 84·5 [IQR 78·0 to 91·3] and 81·0 [75·4 to 87·6], respectively) and volatile anaesthetic use was 0·26 minimum alveolar concentration (30%) lower (0·62 [0·52 to 0·73] and 0·88 [0·74 to 1·04], respectively) in the BIS 50 than the BIS 35 group. 1-year mortality was 6·5% (212 patients) in the BIS 50 group and 7·2% (238 patients) in the BIS 35 group (hazard ratio 0·88, 95% CI 0·73 to 1·07, absolute risk reduction 0·8%, 95% CI −0·5 to 2·0). Grade 3 adverse events occurred in 954 (29%) patients in the BIS 50 group and 909 (27%) patients in the BIS 35 group; and grade 4 adverse events in 265 (8%) and 259 (8%) patients, respectively. The most commonly reported adverse events were infections, vascular disorders, cardiac disorders, and neoplasms. Interpretation: Among patients at increased risk of complications after major surgery, light general anaesthesia was not associated with lower 1-year mortality than deep general anaesthesia. Our trial defines a broad range of anaesthetic depth over which anaesthesia may be safely delivered when titrating volatile anaesthetic concentrations using a processed electroencephalographic monitor. Funding: Health Research Council of New Zealand; National Health and Medical Research Council, Australia; Research Grant Council of Hong Kong; National Institute for Health and Research, UK; and National Institutes of Health, USA.

AB - Background: An association between increasing anaesthetic depth and decreased postoperative survival has been shown in observational studies; however, evidence from randomised controlled trials is lacking. Our aim was to compare all-cause 1-year mortality in older patients having major surgery and randomly assigned to light or deep general anaesthesia. Methods: In an international trial, we recruited patients from 73 centres in seven countries who were aged 60 years and older, with significant comorbidity, having surgery with expected duration of more than 2 h, and an anticipated hospital stay of at least 2 days. We randomly assigned patients who had increased risk of complications after major surgery to receive light general anaesthesia (bispectral index [BIS] target 50) or deep general anaesthesia (BIS target 35). Anaesthetists also nominated an appropriate range for mean arterial pressure for each patient during surgery. Patients were randomly assigned in permuted blocks by region immediately before surgery, with the patient and assessors masked to group allocation. The primary outcome was 1-year all-cause mortality. The trial is registered with the Australian New Zealand Clinical Trials Registry, ACTRN12612000632897, and is closed to accrual. Findings: Patients were enrolled between Dec 19, 2012, and Dec 12, 2017. Of the 18 026 patients screened as eligible, 6644 were enrolled, randomly assigned to treatment or control, and formed the intention-to-treat population (3316 in the BIS 50 group and 3328 in the BIS 35 group). The median BIS was 47·2 (IQR 43·7 to 50·5) in the BIS 50 group and 38·8 (36·3 to 42·4) in the BIS 35 group. Mean arterial pressure was 3·5 mm Hg (4%) higher (median 84·5 [IQR 78·0 to 91·3] and 81·0 [75·4 to 87·6], respectively) and volatile anaesthetic use was 0·26 minimum alveolar concentration (30%) lower (0·62 [0·52 to 0·73] and 0·88 [0·74 to 1·04], respectively) in the BIS 50 than the BIS 35 group. 1-year mortality was 6·5% (212 patients) in the BIS 50 group and 7·2% (238 patients) in the BIS 35 group (hazard ratio 0·88, 95% CI 0·73 to 1·07, absolute risk reduction 0·8%, 95% CI −0·5 to 2·0). Grade 3 adverse events occurred in 954 (29%) patients in the BIS 50 group and 909 (27%) patients in the BIS 35 group; and grade 4 adverse events in 265 (8%) and 259 (8%) patients, respectively. The most commonly reported adverse events were infections, vascular disorders, cardiac disorders, and neoplasms. Interpretation: Among patients at increased risk of complications after major surgery, light general anaesthesia was not associated with lower 1-year mortality than deep general anaesthesia. Our trial defines a broad range of anaesthetic depth over which anaesthesia may be safely delivered when titrating volatile anaesthetic concentrations using a processed electroencephalographic monitor. Funding: Health Research Council of New Zealand; National Health and Medical Research Council, Australia; Research Grant Council of Hong Kong; National Institute for Health and Research, UK; and National Institutes of Health, USA.

UR - http://www.scopus.com/inward/record.url?scp=85075146899&partnerID=8YFLogxK

U2 - 10.1016/S0140-6736(19)32315-3

DO - 10.1016/S0140-6736(19)32315-3

M3 - Article

VL - 394

SP - 1907

EP - 1914

JO - Lancet

JF - Lancet

SN - 0140-6736

IS - 10212

ER -

Australian and New Zealand College of Anaesthetists Clinical Trials Network, Balanced Anaesthesia Study Group. Anaesthetic depth and complications after major surgery: an international, randomised controlled trial. The Lancet. 2019 Nov 23;394(10212):1907-1914. https://doi.org/10.1016/S0140-6736(19)32315-3