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Trial registered on ANZCTR

Registration number
Ethics application status
Submitted, not yet approved
Date submitted
Date registered
Date last updated
Date data sharing statement initially provided
Type of registration
Prospectively registered

Titles & IDs
Public title
Does preoperative dietitian-led Very Low Calorie Diet (VLCD)-based intervention reduce unfavourable elective surgery outcomes for patients with obesity?
Scientific title
A single-site, randomised, controlled trial to establish the impact of preoperative dietitian-led Very Low Calorie Diet (VLCD)-based intervention on unfavourable elective surgery outcomes associated with obesity.
Secondary ID [1] 302346 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Obesity 319121 0
Condition category
Condition code
Diet and Nutrition 317083 317083 0 0
Surgery 317084 317084 0 0
Other surgery

Study type
Description of intervention(s) / exposure
The intervention is a Very Low Calorie Diet (VLCD) which utilises meal replacement products (Optifast or Optislim) providing ~800kcal/day and will be individualised through dietitian-led treatment. The VLCD will include the oral consumption of 1-4 meal replacement products, with an additional 2 cups of non-starchy vegetables and at least 2 litres of non-caffeinated, calorie-free fluids. Dependent on lifestyle factors, age, and ability to adhere to the diet, participants will be recommended to consume variations of the described VLCD, utilising 1-4 meal replacement products, and specific portions of allowed foods.

The diet will be prescribed by the dietitian at the participants' first dietitian appointment, which will be 4-12 weeks away from surgery, depending on surgery type and category (waiting times) for surgery. The participants will be asked to start the diet as soon as they can following the first dietitian appointment (where education regarding the diet will be given).

Participants will attend from 2-6 dietitian appointments where they will be weighed and adherence to the diet will be monitored.

The dietitian appointments will be administered via an outpatient (clinic) hospital setting, and the participants will be asked to follow the diet at home while undertaking their usual life. They will not be admitted to hospital for administration of the intervention.

To monitor adherence, a dietary adherence tool will be used to measure self-reported prescription to the diet. This diet measures how many days within the last 14 days where the diet was adhered to according to specific measures of adherence (i.e. number of products, times 'non-allowed foods' were eaten) to create an overall % adherence measure.
Intervention code [1] 318637 0
Intervention code [2] 319010 0
Treatment: Other
Comparator / control treatment
The control group will not receive any dietary intervention. Their care will remain under standard preoperative processes, which generally involve assessment by their surgeon for booking and consenting for surgery and awaiting a surgical date with no interim intervention. They may attend appointments with relevant staff and receive pathology testing as part of usual perioperative care at the study site. Apart from the two time-points where their measurements are taken for the study (described below), there will be no change to usual care.
Control group

Primary outcome [1] 325632 0
Intraoperative time, in minutes, defined as the time from incision to completion of wound closure. Multiple studies have shown that surgeries resulting in complications had longer operative times than those that did not, and higher BMI is correlated with longer operating time, with a 14% increase in the likelihood of complications for every 30 min of additional operating time.
Timepoint [1] 325632 0
At time of surgery
Secondary outcome [1] 388602 0
Composite secondary outcome: unfavourable surgical outcomes:

Deep joint infection
Persistent wound drainage, defined as continued fluid extrusion from the operative site occurring beyond 72 hours postoperatively
Atelectasis (lung collapse)
Deep vein thrombosis
Pulmonary embolism
Post-operative pulmonary complication
Unplanned injury to other abdominal organs during surgery
Myocardial infarction / Cardiac arrest
Cerebral Vascular Accident / Transient Ischaemic Attack
Hospital acquired Pressure Injury
Intensive Care Unit bed requirement, number of days
Unplanned intubation, failed intubation
On ventilator >48hours
Laparoscopic converted to open procedure
Requirement for blood transfusion
Anastomotic leak
Organ space infection (e.g. abscess)
Unplanned presentation to emergency department resulting from surgery
Unplanned re-admission to hospital resulting from surgery
Requirement for rehabilitation
Acute Kidney Injury
Urinary Tract Infection
Surgical wound dehiscence / breakdown / failure
Haematoma / Seroma formation
Necrotic tissue formation
Surgical site infection
Biliary leakage
Bile duct injury
Arterial injury
Peripheral nerve injury
Unplanned return to operating theatre
Requirement for ventilation
Requirement for ultrasound-assisted intravenous access
Operation time (minutes)
Anaesthesia induction time for surgery (minutes)
Total operating room time (minutes)
Estimated blood loss during operation (mL)
Length of Stay (days)

Data to determine outcomes will be obtained from participants' electronic medical records.

Timepoint [1] 388602 0
Up to 30 days post-surgery
Secondary outcome [2] 388606 0
Composite secondary outcome: change in anthropometric measures:

Weight (kg) - via standing scales
Waist Circumference (cm) - via tape measure
Hip circumference (cm) - via tape measure
Neck circumference (cm) - via tape measure
Waist:Hip Ratio - calculated from waist and hip circumferences
Lean Body Mass % and Fat Mass % (via Bioimpedence Analysis equipment - 'Fresenius Composition Monitor')
BMI (kg/m2) - via calculation of weight (kg) / height (metres) squared

Timepoint [2] 388606 0
Time point 1. At time of recruitment, or as close as possible to that time

Time point 2. At time of surgery, or as close as possible to that time
Secondary outcome [3] 388609 0
Composite outcome: Change in surgical risk:
Measured at baseline and completion for both groups:

ASA score (anaesthetic physical status classification)
NSQUIP score (calculates risks of surgical complications occurring based on demographic, medical and anthropometric measures)

Timepoint [3] 388609 0
Time point 1. At time of recruitment, or as close as possible to that time

Time point 2. At time of surgery, or as close as possible to that time
Secondary outcome [4] 389505 0
Health-related Quality of life using the World Health Organisation Quality of Life Tool (Brief version) - WHOQOL-BREF
Timepoint [4] 389505 0
At start and at completion of dietary intervention

Key inclusion criteria
• greater than or equal to 18 years old, no maximum age, any gender
•BMI (Body Mass Index) greater than or equal to 30kg/m2
•Booked for General, Colorectal, Gynaecological, and Orthopaedic surgical procedures. Participants booked and on the waiting list for Category 2 (up to 90 days until surgery) or Category 3 (up to 365 days until surgery) procedures,

Minimum age
18 Years
Maximum age
No limit
Both males and females
Can healthy volunteers participate?
Key exclusion criteria

• Type 1 Diabetes
• Metastatic cancer
• Liver or kidney failure
• Acute cardiovascular disease
• Pregnant/breastfeeding / preparing or undergoing IVF
• Malnourished or Malnutrition Screening Tool (25) score >2
• Overt psychosis or severe mental impairment
• Minor procedures which do not require penetration or exposure of a body cavity
• Other reason(s) which may make them unsafe for VLCD based treatment as per clinical judgement of their treating surgeon (e.g. frailty or other advanced disease).

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Group allocations will be placed in a sealed opaque envelope prior to the trial and at the time of recruitment and informed consent, the envelopes will be used to allocate participants into either control or intervention group. Allocation will be concealed as neither the researcher nor participant will be able to foresee their assignment.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Prior to recruitment, an independent statistician will develop randomly generated group allocations using statistical software. The statistician will seal the envelopes prior to activation of the trial.
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?

Intervention assignment
Other design features
Not Applicable
Type of endpoint(s)
Statistical methods / analysis
A power calculation has been performed to establish adequate sample size to answer the primary hypothesis and to detect a statistically significant difference in the primary research outcome between two groups.
From examination of the literature in this area we can predict a potential reduction in intraoperative time of at least 15 minutes resulting from the intervention. Studies show a 16 minute reduction in intraoperative time between obese and non-obese patients for joint replacements(46), 43 minute reduction for laparoscopic hysterectomy (47); and from a recent RCT, 18 minute reduction in intraoperative time for general surgery patients who were provided eight weeks of preoperative VLCD intervention (37). To detect this difference with equal standard deviations between groups using a.05 with 80% power, =n=72 are needed in each arm (total =n=144).

There are ~1383 adult patients on eligible elective surgery waiting lists at Logan Hospital each year, with ~40% of these meeting inclusion criteria. Allowing for 30% of these to decline to participate and =10% to withdraw (based on a recent RCT in this area) we aim to recruit n==18 per month over nine months, which is feasible to accomplish within this timeframe.

Data will be analysed using SPSS, and an ‘intention to treat’ analysis method will be used. Comparisons between two groups will be analysed using appropriate analysis such as t-tests, chi squared tests, regression analysis and linear mixed models analysis where required. Statisticians will be consulted throughout the project to ensure appropriate analysis.

Recruitment status
Not yet recruiting
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment in Australia
Recruitment state(s)
Recruitment hospital [1] 17970 0
Logan Hospital - Meadowbrook
Recruitment postcode(s) [1] 31845 0
4131 - Meadowbrook

Funding & Sponsors
Funding source category [1] 306777 0
Name [1] 306777 0
Logan Hospital
Address [1] 306777 0
Cnr Armstrong Rd &, Loganlea Rd, Meadowbrook QLD 4131
Country [1] 306777 0
Primary sponsor type
Queensland University of Technology
149 Victoria Park Rd, Kelvin Grove QLD 4059
Secondary sponsor category [1] 308010 0
Name [1] 308010 0
Address [1] 308010 0
Country [1] 308010 0

Ethics approval
Ethics application status
Submitted, not yet approved
Ethics committee name [1] 306940 0
Metro South Human Research Ethics Committee
Ethics committee address [1] 306940 0
Armstrong Rd &, Loganlea Rd, Meadowbrook QLD 4131
Ethics committee country [1] 306940 0
Date submitted for ethics approval [1] 306940 0
Approval date [1] 306940 0
Ethics approval number [1] 306940 0
Ethics committee name [2] 307269 0
University Human Research Ethics Committee - QUT
Ethics committee address [2] 307269 0
Queensland University of Technology

149 Victoria Park Rd, Kelvin Grove QLD 4059
Ethics committee country [2] 307269 0
Date submitted for ethics approval [2] 307269 0
Approval date [2] 307269 0
Ethics approval number [2] 307269 0

Brief summary
The aim of this research is to evaluate the impact of a preoperative dietitian-led VLCD intervention to determine whether the intervention reduces incidence of unfavourable surgical outcomes arising from elective, non-bariatric surgery in adults with obesity.

It is hypothesised that obese adult patients who receive preoperative dietitian-led VLCD-based treatment will have shorter operating time and fewer unfavourable surgical outcomes than controls.

This study will be a parallel group, two-arm, superiority randomised controlled trial with 1:1 allocation ratio.

The study population will be obese adult patients on elective surgery waiting lists at Logan Hospital for a range of general, colorectal, gynaecological, and orthopaedic procedures.

In absence of appropriate literature, this intervention is not being widely adopted despite likely improved surgical outcomes and cost-benefits. This research will significantly contribute to the small body of literature and likely highlight the need and allow for more widely accepted implementation of this intervention across a variety of surgery types.

Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 105518 0
Ms Sally Griffin
Address 105518 0
Nutrition & Dietetics Department
Logan Hospital
Cnr Armstrong and Loganlea Rds
Meadowbrook QLD 4131
Country 105518 0
Phone 105518 0
+61 732998710
Fax 105518 0
Email 105518 0
Contact person for public queries
Name 105519 0
Ms Sally Griffin
Address 105519 0
Nutrition & Dietetics Department
Logan Hospital
Cnr Armstrong and Loganlea Rds
Meadowbrook QLD 4131
Country 105519 0
Phone 105519 0
+61 732998710
Fax 105519 0
Email 105519 0
Contact person for scientific queries
Name 105520 0
Ms Sally Griffin
Address 105520 0
Nutrition & Dietetics Department
Logan Hospital
Cnr Armstrong and Loganlea Rds
Meadowbrook QLD 4131
Country 105520 0
Phone 105520 0
+61 732998710
Fax 105520 0
Email 105520 0

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
No/undecided IPD sharing reason/comment
What supporting documents are/will be available?
No other documents available
Summary results
No Results