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Trial registered on ANZCTR


Registration number
ACTRN12621000958886p
Ethics application status
Submitted, not yet approved
Date submitted
20/05/2021
Date registered
22/07/2021
Date last updated
22/07/2021
Date data sharing statement initially provided
22/07/2021
Type of registration
Prospectively registered

Titles & IDs
Public title
Retrospective database study investigating an association between intraoperative oxygen administration and recovery after surgery
Scientific title
REtrospective Database Cohort Study investigating an association between intraoperative OXygen exposure and days alive and out of hospital at 90 days (DAOH90) - REDOX study
Secondary ID [1] 304261 0
Nil known
Universal Trial Number (UTN)
Trial acronym
REDOX - REtrospective Database Cohort Study investigating an association between intraoperative OXygen exposure and DAOH90
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Surgical site infection 321982 0
Mortality 321983 0
Postoperative recovery 321984 0
Non-infection related postoperative complications 321985 0
oxygen administration 321986 0
Condition category
Condition code
Anaesthesiology 319705 319705 0 0
Anaesthetics

Intervention/exposure
Study type
Observational
Patient registry
False
Target follow-up duration
Target follow-up type
Description of intervention(s) / exposure
The exposure of interest is the time-weighted average intraoperative oxygen (FiO2) in patients undergoing surgery and meeting study eligibility criteria within the defined study timeframe (Adult patients admitted to Auckland City Hospital between 01 July 2006 and 30 June 2020 undergoing non-cardiothoracic surgery under general anaesthesia with an operative duration greater than or equal to 120 minutes). Specifically, patients who were exposed to a time-weighted average FiO2 >/= 0.8 (liberal oxygen therapy) will be compared to those exposed to FiO2 < 0.8.

The average time-weighted intraoperative oxygen exposure will be calculated from all available recordings of inspired oxygen fraction from the intraoperative anaesthesia record throughout the entire duration of surgery.
Intervention code [1] 320603 0
Not applicable
Comparator / control treatment
The control group or comparator arm will be patients who were exposed to a time-weighted average intraoperative fraction of inspired oxygen of < 0.8.
Control group
Active

Outcomes
Primary outcome [1] 327584 0
Days alive and out of hospital will be assessed by link data records of included patients with the Ministry of Health National Minimum Dataset using patient National Health Index Number (NHI)
Timepoint [1] 327584 0
90 days post surgery
Secondary outcome [1] 395749 0
Surgical site infection will be assessed by link data records of included patients with the Ministry of Health National Minimum Dataset using patient NHI
Timepoint [1] 395749 0
90 days post surgery
Secondary outcome [2] 395750 0
Respiratory complication will be assessed by link data records of included patients with the Ministry of Health National Minimum Dataset using patient NHI
Timepoint [2] 395750 0
90 days post surgery
Secondary outcome [3] 395751 0
ICU admission will be assessed by link data records of included patients with the Ministry of Health National Minimum Dataset and hospital records using patient NHI
Timepoint [3] 395751 0
90 days post surgery
Secondary outcome [4] 395752 0
ICU length of stay will be assessed by link data records of included patients with the Ministry of Health National Minimum Dataset and hospital medical records using patient NHI
Timepoint [4] 395752 0
90 days post-surgery
Secondary outcome [5] 395753 0
Hospital length of stay will be assessed by link data records of included patients with the Ministry of Health National Minimum Dataset using patient NHI
Timepoint [5] 395753 0
90 days post-surgery
Secondary outcome [6] 395754 0
In hospital mortality will be assessed by link data records of included patients with the Ministry of Health National Minimum Dataset using patient NHI
Timepoint [6] 395754 0
90 days post-surgery
Secondary outcome [7] 395756 0
Mortality will be assessed by link data records of included patients with the Ministry of Health National Minimum Dataset using patient NHI
Timepoint [7] 395756 0
90 days post-surgery
Secondary outcome [8] 397783 0
Intraoperative saturations as measured by pulse oximetry (SpO2) will be collected will be assessed by linking data records of included patients with the SAFERSleep electronic anaesthesia record using patient NHI. These data will be used to calculate highest, lowest and mean SpO2
Timepoint [8] 397783 0
From the time of induction of anaesthesia to the end of the anaesthesia record at the completion of surgery

Eligibility
Key inclusion criteria
Adult patients (age >/= 18 years) admitted to Auckland City Hospital between 01 July 2006 and 30 June 2020 undergoing non-cardiothoracic surgery under general anaesthesia with an operative duration >/= 120 minutes
Minimum age
18 Years
Maximum age
No limit
Gender
Both males and females
Can healthy volunteers participate?
No
Key exclusion criteria
Patient data sets will only be included in the study analysis once and databases will be screened for duplicates, which will be removed. For participants with multiple admissions meeting inclusion criteria, the study will consider their first admission within the study period that meets inclusion criteria as the baseline.

Study design
Purpose
Natural history
Duration
Longitudinal
Selection
Defined population
Timing
Retrospective
Statistical methods / analysis
The sample will include all patients undergoing surgery at the study site, since the institution of the Ministry of Health National Non-Admitted Patient Collection in 2006 to achieve maximum statistical power.

Analysis principles are as follows:
- Continuous parametric variables will be analysed using parametric methods (e.g. t test and quantile regression).
- Assumptions of linearity will be tested for the quantile regression analysis.
- All tests will be two-sided
- The nominal level of significance (a) for the primary outcome will be 0.05
- The nominal level of statistical significance (a) for all secondary outcomes will be 0.01.
- No formal adjustments for multiplicity of testing will be applied, but outcomes will be ordered by degree of importance (i.e., primary versus secondary) and significant test results will be interpreted considering the multiple comparisons made.
- Primary and secondary outcomes will be analysed using predefined subgroups.
- Tests of normality will not be conducted for the primary outcome as the non-normality of the DAOH90 outcome has been well documented previously.
- Tests of normality will be conducted for the intraoperative time-weighted SpO2 and lowest intraoperative SpO2, duration of ICU admission and hospital length of stay secondary outcomes. Secondary outcomes such as postoperative SSI at 30 days, postoperative respiratory complication at 90 days, postoperative non-infection related complication at 90- days, postoperative ICU admission rate at 90- days and in-hospital mortality will not be tested for normality as these are binomial measures.
- Analyses will be conducted using R version 4.0.3

Recruitment
Recruitment status
Not yet recruiting
Date of first participant enrolment
Anticipated
Actual
Date of last participant enrolment
Anticipated
Actual
Date of last data collection
Anticipated
Actual
Sample size
Target
Accrual to date
Final
Recruitment outside Australia
Country [1] 23713 0
New Zealand
State/province [1] 23713 0
Auckland

Funding & Sponsors
Funding source category [1] 308640 0
University
Name [1] 308640 0
Auckland University Department of Medicine - Anaesthesia
Address [1] 308640 0
85 Park Road, Grafton, Auckland 1023
Country [1] 308640 0
New Zealand
Primary sponsor type
Individual
Name
Daniel Frei
Address
Department of Anaesthesia and Pain Medicine
Wellington Hospital
Riddiford Street
Newtown
Wellington 6021
Country
New Zealand
Secondary sponsor category [1] 309519 0
None
Name [1] 309519 0
Address [1] 309519 0
Country [1] 309519 0

Ethics approval
Ethics application status
Submitted, not yet approved
Ethics committee name [1] 308566 0
Central Health and Disability Ethics Committee 21/CEN/141
Ethics committee address [1] 308566 0
133 Molesworth Street
Thorndon
Wellington 6011
Ethics committee country [1] 308566 0
New Zealand
Date submitted for ethics approval [1] 308566 0
12/05/2021
Approval date [1] 308566 0
Ethics approval number [1] 308566 0

Summary
Brief summary
The aim of the proposed study is to investigate potential associations between oxygen administration during major surgery, and postoperative recovery. The study will be collect data from adult patients having non-cardiothoracic surgery under general anaesthesia at Auckland City Hospital over a 15 year time period, Our hypothesis is that the administration of higher levels of intraoperative oxygen, fraction inspired oxygen (FiO2) = 0.8 is associated with a slower recovery from surgery, compared with non-liberal oxygen therapy (FiO2 < 0.8). The study will look at a number of aspects of postoperative recovery, including the number of days patients spend in their own homes in the first 90 days after surgery, the rate of wound infections after surgery, and other major complications and death following surgery.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 111162 0
Dr Daniel Frei
Address 111162 0
Department of Anaesthesia and Pain Medicine
Wellington Hospital
Riddiford Street, Newtown
Wellington 6021
Country 111162 0
New Zealand
Phone 111162 0
+64 4 385 5999
Fax 111162 0
Email 111162 0
daniel.frei@ccdhb.org.nz
Contact person for public queries
Name 111163 0
Dr Daniel Frei
Address 111163 0
Department of Anaesthesia and Pain Medicine
Wellington Hospital
Riddiford Street, Newtown
Wellington 6021
Country 111163 0
New Zealand
Phone 111163 0
+64 4 385 5999
Fax 111163 0
Email 111163 0
daniel.frei@ccdhb.org.nz
Contact person for scientific queries
Name 111164 0
Dr Daniel Frei
Address 111164 0
Department of Anaesthesia and Pain Medicine
Wellington Hospital
Riddiford Street, Newtown
Wellington 6021
Country 111164 0
New Zealand
Phone 111164 0
+64 4 385 5999
Fax 111164 0
Email 111164 0
daniel.frei@ccdhb.org.nz

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
Yes
What data in particular will be shared?
All data will be obtained from existing databases. Specific use of data from the Ministry of Health databases requires individual ethics approval and must be sought by other parties wishing to obtain data. De-identified individual patient data stored for this study will be provided if relevant ethical approvals have been obtained.
When will data be available (start and end dates)?
Immediately following publication ending 5 years after main results publication
Available to whom?
Researchers who provide a methodologically sound proposal and have obtained the required ethical and regulatory approvals
Available for what types of analyses?
To be determined on a case by case basis
How or where can data be obtained?
Access subject to approvals by the Principal Investigator. Submissions via email to daniel.frei@ccdhb.org.nz
What supporting documents are/will be available?
No other documents available
Summary results
No Results