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Trial registered on ANZCTR


Registration number
ACTRN12625000297426
Ethics application status
Approved
Date submitted
2/04/2025
Date registered
15/04/2025
Date last updated
15/04/2025
Date data sharing statement initially provided
15/04/2025
Type of registration
Retrospectively registered

Titles & IDs
Public title
The effect of body weight on outcomes in elderly patients with critical illness
Scientific title
The effect of body mass index on outcomes in nonagenarians and centenarians with critical illness
Secondary ID [1] 314107 0
None
Universal Trial Number (UTN)
U1111-1321-0967
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Mortality 336895 0
Intensive care 336894 0
Body mass index 336897 0
Post operative complications 336896 0
Condition category
Condition code
Physical Medicine / Rehabilitation 333364 333364 0 0
Other physical medicine / rehabilitation
Diet and Nutrition 333367 333367 0 0
Obesity
Public Health 333365 333365 0 0
Health service research
Surgery 333366 333366 0 0
Other surgery

Intervention/exposure
Study type
Observational
Patient registry
False
Target follow-up duration
Target follow-up type
Description of intervention(s) / exposure
In this study we will be observing the postoperative outcomes in patients aged greater than 90 years who have been at admitted to Intensive Care Unit (ICU) across Australia and New Zealand.

The main outcome being observed is hospital mortality. Secondary outcomes include ICU mortality, invasive treatments prescribed in ICU, including mechanical ventilation, renal replacement therapy, and use of vasoactive medications and inotropes. The duration of observation will be from ICU admission to death in either ICU or hospital.

The exposure will include nonagenarians who are underweight (body mass index < 18.5 kg/m2), or overweight (body mass index between 25.0 kg/m2 and 30.0 kg/m2.

Data will be extracted from the Australian and New Zealand Intensive Care Adult Patient Database for patients admitted to the ICU between 2010 and 2023.
Intervention code [1] 330680 0
Diagnosis / Prognosis
Comparator / control treatment
The control will include nonagenarians who are normal weight i.e. a body mass index between 18.5 kg/m2 and 25.0 kg/m2.

Data will be extracted from the Australian and New Zealand Intensive Care Adult Patient Database for patients admitted to the ICU between 2010 and 2023.
Control group
Historical

Outcomes
Primary outcome [1] 340942 0
The second primary outcome will be to evaluate hospital mortality in nonagenarians admitted to intensive care with high and low body mass indexes, and compare these patients to those with a normal body mass index. This will be a binary outcome measure of whether patients survive or do not survive their hospital admission.
Timepoint [1] 340942 0
The timepoint will from admission to ICU to death in the hospital.
Primary outcome [2] 340941 0
The primary outcome will be to evaluate intensive care mortality in nonagenarians admitted to intensive care with high and low body mass indexes and compared those patients thsoe with a normal body mass index. This will be a binary outcome measure of whether patients survive or do not survive their ICU admission.
Timepoint [2] 340941 0
The timepoint will be from admission to ICU to death in ICU.
Secondary outcome [1] 445940 0
Other secondary outcomes will include hospital length of stay, measured from hospital admission to hospital discharge or death. Predictors of hospital stay will also be analyzed,
Timepoint [1] 445940 0
This will be calculated retrospectively from admission to hospital, to hospital discharge or death.
Secondary outcome [2] 445942 0
Other secondary outcomes will include whether patients were prescribed invasive treatments ICU. These will be a composite outcome of mechanical ventilation, renal replacement therapy, and use of vasoactive medications and inotropes. The duration of observation will be from ICU admission to death in ICU or hospital.
Timepoint [2] 445942 0
asas
Secondary outcome [3] 445542 0
The secondary outcome will include ICU length of stay, measured from ICU admission to ICU discharge. Predictors of length of ICU stay will also be assessed.
Timepoint [3] 445542 0
This will be calculated retrospectively from admission to ICU, to ICU discharge or ICU death.

Eligibility
Key inclusion criteria
Inclusion criteria will be patients aged >90 years and <100 years who require an admission to the ICU for any indication.
Minimum age
90 Years
Maximum age
No limit
Sex
Both males and females
Can healthy volunteers participate?
No
Key exclusion criteria
None

Study design
Purpose
Natural history
Duration
Longitudinal
Selection
Defined population
Timing
Retrospective
Statistical methods / analysis
Baseline characteristics will be reported as counts and percentages and means with standard deviations, or medians and interquartile ranges (IQRs) where data were non-normally distributed.

Missing data will be considered missing completely at random (MCAR). Patients with missing height, weight, or outcomes will be excluded from the analysis. All other missing data will be imputed using multivariate imputation by chained equations with 20 imputations and 40 iterations.

We will use entropy balancing for the continuous exposure of body mass index (BMI) to produce a balanced patient cohort for causal effect analysis. Entropy balancing is an inverse probability weighting method that guarantees perfect balance for all covariates. Average exposure-response functions (AERFs) will be used to assess the impact of the exposure (BMI) on the expected potential outcome across the full range of the exposure values. An omnibus Wald-type test will be used to determine AERF significance to the null hypothesis.

Logistic and linear regression analyses will also conducted on the balanced cohort for each primary and secondary outcome across BMI subgroups.

We plan to apriori conduct a subgroup analysis, including only patients with known chronic cardiovascular disease (CVD) upon ICU admission, to examine outcomes in a cohort who were the subject of previous publications on the ‘obesity paradox’ topic. The obesity paradox refers to the observation that, in certain medical conditions, being overweight or mildly obese appears to be associated with better survival outcomes compared to being of normal weight or underweight.

Effect estimates will be presented as odds ratios or adjusted mean differences. Results will be considered significant if P < 0.05. All statistical analyses will be conducted in R. The WeightThem package will be used for entropy balancing.

Recruitment
Recruitment status
Completed
Date of first participant enrolment
Anticipated
Actual
19/11/2024
Date of last participant enrolment
Anticipated
Actual
17/01/2025
Date of last data collection
Anticipated
Actual
1/04/2025
Sample size
Target
12510
Accrual to date
Final
12510
Recruitment in Australia
Recruitment state(s)
VIC
Recruitment hospital [1] 27686 0
The Alfred - Melbourne
Recruitment hospital [2] 27685 0
Austin Health - Austin Hospital - Heidelberg
Recruitment postcode(s) [1] 43873 0
3084 - Heidelberg
Recruitment postcode(s) [2] 43874 0
3004 - Melbourne

Funding & Sponsors
Funding source category [1] 318613 0
Government body
Name [1] 318613 0
Austin Health
Country [1] 318613 0
Australia
Primary sponsor type
Government body
Name
Austin Health
Address
Country
Australia
Secondary sponsor category [1] 321019 0
None
Name [1] 321019 0
Address [1] 321019 0
Country [1] 321019 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 317217 0
Alfred Hospital Ethics Committee
Ethics committee address [1] 317217 0
Ethics committee country [1] 317217 0
Australia
Date submitted for ethics approval [1] 317217 0
15/02/2024
Approval date [1] 317217 0
30/04/2024
Ethics approval number [1] 317217 0
Project No: 253/24

Summary
Brief summary
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 140378 0
Prof Laurence Weinberg
Address 140378 0
Department of Anaesthesia, Austin Health, 145 Studley Road, Heidelberg, VIC, 3084
Country 140378 0
Australia
Phone 140378 0
+61 413244770
Fax 140378 0
Email 140378 0
[email protected]
Contact person for public queries
Name 140379 0
Laurence Weinberg
Address 140379 0
Department of Anaesthesia, Austin Health, 145 Studley Road, Heidelberg, VIC, 3084
Country 140379 0
Australia
Phone 140379 0
+61 413244770
Fax 140379 0
Email 140379 0
[email protected]
Contact person for scientific queries
Name 140380 0
Laurence Weinberg
Address 140380 0
Department of Anaesthesia, Austin Health, 145 Studley Road, Heidelberg, VIC, 3084
Country 140380 0
Australia
Phone 140380 0
+61 413244770
Fax 140380 0
Email 140380 0
[email protected]

Data sharing statement
Will the study consider sharing individual participant data?
No
No IPD sharing reason/comment: As this is an observational study, patients have not provided consent for their data to be shared.



What supporting documents are/will be available?

No Supporting Document Provided


Results publications and other study-related documents

Documents added manually
No documents have been uploaded by study researchers.

Documents added automatically
No additional documents have been identified.