Depth of Anaesthesia and Long-term Survival: The Balanced Anaesthesia Follow-up Study

Completed

• Conditions: Post-Operative Confusion; Surgery--Complications; Long Term Adverse Effects; Cognitive Dysfunction, Postoperative
• Interventions: Other: Anaesthesia Depth

• Registration Number: NCT04965324
• Lead Sponsor: Auckland City Hospital

Brief Summary

Anaesthetic depth and complications after major surgery: an international, randomised controlled trial - The BALANCED trial.

In this large, international, randomised controlled trial that enrolled patients aged 60 years and over with significant comorbidity and at increased risk of complications after major surgery, we found no evidence that light general anaesthesia (bispectral index 50) was superior to deep general anaesthesia (bispectral index 35) in reducing 1-year mortality. The BALANCED long term follow up study will look at whether depth of anesthesia affects long term (beyond 1 year) survival.

The primary hypothesis is that targetting BIS 50 will result in superior long term survival compared to targetting BIS 35.

The two secondary hypotheses are that BIS titration to BIS 50 will

1. reduce local cancer recurrence or metastatic spread and consequently improve long-term survival

2. reduce postoperative delirium and associated cognitive impairment and consequently improve long-term survival

Both these mechanisms would be expected to take longer to manifest as reduced survival than 1-year all-cause mortality primary outcome in the Balanced trial. Trials of cancer outcomes often use 5-year survival or similar timeframes to determine evidence of clinical benefit. A steeper cognitive trajectory due to intermediate outcomes such as delirium and cognitive impairment may take longer than 1 year to produce a clinically important difference in survival 30. The 10.6% relative risk reduction seen in the Balanced trial could translate to a statistically and clinically meaningful survival difference in this high-risk population. This population may have 5-year survival of \~80% translating to an absolute survival difference of \~2% potentially (if the \~10% RRR is maintained beyond 1 year). The alternative is that there is no long-term mortality difference which would provide continuing clinical guidance of the safety of current practice in patients who are not at high risk of delirium. This study could provide a rationale for trials in larger populations (such as the total Balanced trial population) or targeted subgroups such as cancer and delirium to provide further mechanistic insights.

Long-term survival is an important patient-centred outcome. The mechanisms described above may manifest in longer-term outcomes providing a clear rationale for the current trial.

Detailed Description

Not available

Study Timeline

• Study Start: 2012-12-19
• Primary Completion: 2017-12-12
• Study Completion: 2021-05-31
• Status Verified: 2021-07
• Study First Submitted: 2021-07-07
• Study First Submitted QC: 2021-07-07
• Study First Posted: 2021-07-16
• Last Update Submitted: 2021-07-21
• Last Update Posted: 2021-07-23

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 6644

Inclusion Criteria

Not provided

Exclusion Criteria

Not provided

Study & Design

• Study Type: OBSERVATIONAL
• Study Design: Not specified

Arm && Interventions

Group	Intervention	Description
Anaesthesia Depth BIS 50	Anaesthesia Depth	BIS 50
Anaesthesia Depth BIS 35	Anaesthesia Depth	BIS 35

Primary Outcome Measures

Name	Time	Method
Survival	Between one year and eight years after randomization to the BALANCED Trial	Survival

Trial Locations

Locations (1)

Auckland City Hopsital; 🇳🇿 Auckland, New Zealand