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Trial registered on ANZCTR


Registration number
ACTRN12614001334695
Ethics application status
Approved
Date submitted
12/12/2013
Date registered
18/12/2014
Date last updated
27/06/2016
Type of registration
Prospectively registered

Titles & IDs
Public title
Effects of low salt weight loss diets on the way blood vessels work
Scientific title
Effects of weight loss diets low in dietary sodium compared to pre weight loss diet on endothelial function in overweight to obese adults
Secondary ID [1] 283769 0
nil
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Overweight or obese 290743 0
Blood vessel function: flow mediated dilatation, pulse wave velocity and augmentation and blood pressure 290744 0
Condition category
Condition code
Diet and Nutrition 291103 291103 0 0
Obesity

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
This is a randomized controlled cross over study.

Participants will be randomised into two equal groups matched for body mass index (BMI), sex, age.

One group (1) will start with an energy restricted diet using meal replacement low in sodium (meal replacement will be provided for breakfast, lunch and dinner) for 8 weeks followed by a 2 week weight maintenance period on a normal salt diet and finish with a control period of 8 weeks following their normal pre study diet.
The second group (2) will start by following their usual diet for 8 weeks followed by 8 weeks weight loss (as above) finishing with 2 weeks weight maintenance.

This study will last for a total of 18 weeks. Participants will be asked to attend maximum 8 appointments at the University of South Australia. The duration of the visits will vary between 15 minutes and 1.5 hours (visits where all measurements are taken will last approximately 1.5 hours (baseline, after 8 weeks weight loss/ control period and after the 2 weeks weight stable period) visits during the weight loss period will last approximately 15 minutes).

In the weight loss period participants will attend the University clinic every two weeks to be weighed and to collect meal replacement for the next 2 week period (duration of visit approximately 15 minutes).

In the control period participants will be asked to attend the University clinic after 8 weeks (duration approximately 1.5 hours). In this period they will be continuing on their usual diet.

To assess food habits a food frequency questionnaire (FFQ) will be completed a t baseline. 3 day diet diaries will be completed at baseline, after 8 weeks weight loss/control period and after the 2 week weight stable period. As a compliance measure weight loss and amount of meal replacement sachets used will be measured. Participants will be asked to return all used and unused meal replacement sachets to be counted.
Intervention code [1] 288454 0
Lifestyle
Comparator / control treatment
The control period of 8 weeks is a non-intervention period where participants consume their usual diet and do not lose weight
Control group
Active

Outcomes
Primary outcome [1] 291091 0
Flow mediated dilatation (FMD) of the brachial artery will be measured using ultra sound
Timepoint [1] 291091 0
baseline, 8 weeks after either control or weight loss and after 2 weeks weight stability
Primary outcome [2] 291095 0
Pulse wave velocity (PWV) and augmentation index(AI) will be measured using a SphygmoCor Registered Trademark XCEL (AtCor Medical)
Timepoint [2] 291095 0
Baseline, 8 weeks weight loss/ controlm period and after 2 weeks weight stability
Primary outcome [3] 291096 0
Blood pressure (BP) will be measured using and automated sphygmomanometer
Timepoint [3] 291096 0
baseline, 8 weeks after either control or weight loss and after 2 weeks weight stability
Secondary outcome [1] 305995 0
24h urine sodium, potassium will be measures in a certified commercial laboratory
Timepoint [1] 305995 0
baseline, 8 weeks after either control or weight loss and after 2 weeks weight stability
Secondary outcome [2] 305996 0
Bloods for Plasma sodium & potassium, nitrates/nitrites, ICAM-1 & VCAM-1, E-selectin & endothelin-1
Timepoint [2] 305996 0
baseline, 8 weeks after either control or weight loss and after 2 weeks weight stability
Secondary outcome [3] 305997 0
Weight, height and waist circumference
Timepoint [3] 305997 0
All visits

Eligibility
Key inclusion criteria
overweight to obese (BMI greater than or equal to 27 kg/m2) men and women, weight stable within the last 6 months, BP (SBP) <160 mmHg and (DBP) <90 mmHg
Minimum age
18 Years
Maximum age
80 Years
Gender
Both males and females
Can healthy volunteers participate?
No
Key exclusion criteria
BMI less than 27 kg/m2, serious illness e.g. Cancer, liver or kidney disease or not willing or able to follow diet for the study period, alcohol intake above 1 standard drink/day and not willing to decrease intake

Study design
Purpose of the study
Prevention
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Participants from the general population will be recruited via advertisments, flyers and postings on facebook, GumTree and Twitter.
Eligibility to the study will be determined via a short telephone interview.
Allocation will not be concealed
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Participants will be randomized via random number system using the software program clinstat
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?



Intervention assignment
Crossover
Other design features
Phase
Not Applicable
Type of endpoint(s)
Efficacy
Statistical methods / analysis
Participant number
The power to detect a weight difference of 10kg was based on a previous parallel weight study where a change of 10 kg (SD 13) was seen at 6 months and a change in FMD of 1. 5% (SD 2.4) seen in a previous study. This gives us 80% (p<0.05) confidence to determine a difference in FMD of 1.5% with 21 participants in each group. A 30% dropout is expected therefore 56 participants will be recruited.


After testing data for normal distribution, a repeated measures analysis of variance (ANOVA) with meal and time as within-subject factors will be used to assess the effects of diet intervention on the dependent variables over time. Age and BMI will be included as covariates. If there is a significant main effect of time, post hoc comparisons will be performed with Bonferroni’s correction for multiple comparisons to determine changes in the dependent variables relative to baseline. Correlation between variables will be analyzed using Pearson's product-moment coefficient test.

Recruitment
Recruitment status
Completed
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 in Australia
Recruitment state(s)
SA

Funding & Sponsors
Funding source category [1] 288433 0
University
Name [1] 288433 0
University of South Australia
Address [1] 288433 0
City East Campus
University of South Australia
GPO Box 2471
Adelaide
SA 5000
Country [1] 288433 0
Australia
Primary sponsor type
University
Name
University of South Australia
Address
City East Campus
University of South Australia
GPO Box 2471
Adelaide
SA 5000
Country
Australia
Secondary sponsor category [1] 287136 0
None
Name [1] 287136 0
Address [1] 287136 0
Country [1] 287136 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 290308 0
University of South Australia Human Research Ethics Committee
Ethics committee address [1] 290308 0
GPO Box 2471
Adelaide
SA 5001
Ethics committee country [1] 290308 0
Australia
Date submitted for ethics approval [1] 290308 0
16/12/2013
Approval date [1] 290308 0
30/01/2015
Ethics approval number [1] 290308 0
31833

Summary
Brief summary
The purpose of this study is to see if a combination of weight loss and low salt diets have a beneficial effect on how blood vessels work.
We hypothesise that decreasing salt in the diet and losing weight will improve blood vessel function.
Trial website
Trial related presentations / publications
Public notes
Would you like help to lose weight?

OVERWEIGHT VOLUNTEERS WANTED


Effects of weight loss & diet quality on blood vessel function
We will be looking at the effect of weight loss using a low sodium meal replacement diet on markers of cardiovascular disease (all meal replacement will be provided)

We would like to hear from you if you are:

* Over 18 years old
* Overweight (otherwise healthy)

If you would like to learn more, please contact us for further information:

Call Eva Pedersen at 8302 1025

Or E-mail at: eva.pedersen@unisa.edu.au

Research Associate,
University of South Australia, East Campus, North Terrace, Adelaide, SA 5000

Contacts
Principal investigator
Name 44974 0
A/Prof Jennifer Keogh
Address 44974 0
University of South Australia City East Campus North Terrace Adelaide SA 5000
Country 44974 0
Australia
Phone 44974 0
+61 8 8302 2579
Fax 44974 0
Email 44974 0
Jennifer.Keogh@unisa.edu.au
Contact person for public queries
Name 44975 0
A/Prof Jennifer Keogh
Address 44975 0
University of South Australia City East Campus North Terrace Adelaide SA 5000
Country 44975 0
Australia
Phone 44975 0
+61 8 8302 2579
Fax 44975 0
Email 44975 0
Jennifer.Keogh@unisa.edu.au
Contact person for scientific queries
Name 44976 0
A/Prof Jennifer Keogh
Address 44976 0
University of South Australia City East Campus North Terrace Adelaide SA 5000
Country 44976 0
Australia
Phone 44976 0
+61 8 8302 2579
Fax 44976 0
Email 44976 0
Jennifer.Keogh@unisa.edu.au

No information has been provided regarding IPD availability
Summary results
Have study results been published in a peer-reviewed journal?
Other publications
Have study results been made publicly available in another format?
Results – basic reporting
Results – plain English summary