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Trial registered on ANZCTR


Registration number
ACTRN12624000514505
Ethics application status
Approved
Date submitted
3/04/2024
Date registered
26/04/2024
Date last updated
26/04/2024
Date data sharing statement initially provided
26/04/2024
Type of registration
Retrospectively registered

Titles & IDs
Public title
Beliefs and Expectations as Predictors of Response to the Low FODMAP Diet
Scientific title
Psychological variables as predictors of symptom response with the low FODMAP diet: A 6-month longitudinal study in adults with irritable bowel syndrome
Secondary ID [1] 311882 0
HEC18260
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Irritable bowel syndrome 333454 0
Condition category
Condition code
Oral and Gastrointestinal 330124 330124 0 0
Other diseases of the mouth, teeth, oesophagus, digestive system including liver and colon

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
The intervention is the low fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAP) diet.

The intervention will be delivered via online (60-45 minute zooms) one-on-one consults with a dietitian who has experience with gastrointestinal disorders and delivery of the low FODMAP diet.
Consults will be conducted at 3 timepoints: week 0 (pre-Phase 1), week 5 (following completion of Phase 1), week 13 (following completion of Phase 2 and prior to commencing Phase 3).
The education will follow the FODMAP implementation guidelines including elimination, reintroduction and personalisation phases.

Phase 1 Elimination: The education will focus on foods within the patients’ diets that are known to be high in FODMAPs and offering an explanation as to why these foods cause the symptoms related to irritable bowel syndrome (IBS). The patient will be instructed to follow a low FODMAP diet and the dietitian will provide resources that are suitable to the patient they are seeing (e.g. low FODMAP shopping lists, meal plan, food swaps). The elimination period will be followed for 4-weeks.

Phase 2 Reintroduction: Education will focus on continuation of the low FODMAP diet with reintroduction of FODMAPs, where FODMAP-containing foods are used as challenges. Challenge foods are consumed in increasing amounts over 3 days. A symptom diary is kept to document symptoms and responses to each food, to allow determination of the individuals’ threshold to that FODMAP. A three-day washout of the low FODMAP diet is followed before another challenge occurs. The reintroduction phase will be followed for 2-months.

Phase 3 Personalisation: Education will focus on including higher FODMAP containing foods that did not induce symptoms in the diet whilst maintaining symptom relief and increasing variety in the diet. The personalisation phase will be followed for 3-months.

The total duration of the study participation and 3-phase intervention is 25 weeks.
Adherence is monitored via completion of food frequency questionnaire at each timepoint and attendance at each of the 3 dietetic consults.
Intervention code [1] 328348 0
Treatment: Other
Comparator / control treatment
No control group
Control group
Uncontrolled

Outcomes
Primary outcome [1] 337875 0
Gastrointestinal symptoms over the three phases of the low FODMAP diet
Timepoint [1] 337875 0
Pre-dietitian (week 0), immediately post-dietitian (following the first dietitian consultation), at the end of the elimination (week 5), reintroduction (week 13) and personalisation (week 25)
Primary outcome [2] 337971 0
Quality of life over the three phases of the low FODMAP diet
Timepoint [2] 337971 0
Pre-dietitian (week 0), immediately post-dietitian (following the first dietitian consultation), at the end of the elimination (week 5), reintroduction (week 13), and personalisation (week 25)
Primary outcome [3] 338041 0
Credibility and expectancy of treatment response over the three phases of the low FODMAP diet
Timepoint [3] 338041 0
Pre-dietitian (week 0), immediately post-dietitian (following the first dietitian consultation), at the end of the elimination (week 5), reintroduction (week 13) and personalisation (week 25)
Secondary outcome [1] 433565 0
FODMAP restriction
Timepoint [1] 433565 0
Immediately post-dietitian (following the first dietitian consultation), at the end of the elimination (week 5), reintroduction (week 13) and personalisation (week 25)
Secondary outcome [2] 433927 0
Psychological predictors of treatment response over the three phases of the low FODMAP diet
Timepoint [2] 433927 0
Pre-dietitian (week 0), immediately post-dietitian (following the first dietitian consultation), at the end of the elimination (week 5), reintroduction (week 13) and personalisation (week 25)
Secondary outcome [3] 433928 0
Illness perceptions as predictor of treatment response over the three phases of the low FODMAP diet
Timepoint [3] 433928 0
Pre-dietitian (week 0), immediately post-dietitian (following the first dietitian consultation), at the end of the elimination (week 5), reintroduction (week 13) and personalisation (week 25)
Secondary outcome [4] 433929 0
Psychological predictors of treatment response over the three phases of the low FODMAP diet
Timepoint [4] 433929 0
Pre-dietitian (week 0), immediately post-dietitian (following the first dietitian consultation), at the end of the elimination (week 5), reintroduction (week 13) and personalisation (week 25)
Secondary outcome [5] 433930 0
Anxiety as a predictor of treatment response over the three phases of the low FODMAP diet
Timepoint [5] 433930 0
Pre-dietitian (week 0), immediately post-dietitian (following the first dietitian consultation), at the end of the elimination (week 5), reintroduction (week 13) and personalisation (week 25)
Secondary outcome [6] 433931 0
Somatic symptoms as predictors of treatment response over the three phases of the low FODMAP diet
Timepoint [6] 433931 0
Pre-dietitian (week 0), immediately post-dietitian (following the first dietitian consultation), at the end of the elimination (week 5), reintroduction (week 13) and personalisation (week 25)
Secondary outcome [7] 433932 0
Stress as a predictor of treatment response over the three phases of the low FODMAP diet
Timepoint [7] 433932 0
Pre-dietitian (week 0), immediately post-dietitian (following the first dietitian consultation), at the end of the elimination (week 5), reintroduction (week 13) and personalisation (week 25)
Secondary outcome [8] 433933 0
GI-specific anxiety as a predictor of treatment response over the three phases of the low FODMAP diet
Timepoint [8] 433933 0
Pre-dietitian (week 0), immediately post-dietitian (following the first dietitian consultation), at the end of the elimination (week 5), reintroduction (week 13) and personalisation (week 25)
Secondary outcome [9] 433934 0
Behavioural avoidance as a predictor of treatment response over the three phases of the low FODMAP diet
Timepoint [9] 433934 0
Pre-dietitian (week 0), immediately post-dietitian (following the first dietitian consultation), at the end of the elimination (week 5), reintroduction (week 13) and personalisation (week 25)

Eligibility
Key inclusion criteria
Adults who has not yet seen a dietitian for IBS management who had symptoms characterised by the Rome IV criteria, good English literacy skills, stable medication use or stable ongoing psychological therapies in the 12 weeks prior to commencing the study.
Minimum age
18 Years
Maximum age
No limit
Sex
Both males and females
Can healthy volunteers participate?
No
Key exclusion criteria
Pregnant women, paediatrics (<18 years old) and those with gastrointestinal symptoms not pertaining to the Rome IV criteria (such as inflammatory bowel disease, coeliac or dyspepsia).

Study design
Purpose of the study
Treatment
Allocation to intervention
Non-randomised trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?



Intervention assignment
Single group
Other design features
Phase
Not Applicable
Type of endpoint/s
Statistical methods / analysis
Participant number: A power calculation was based on a study by Kaptchuk et al., 2008 which focused on symptom improvement. The two means at the three—week time point for global symptom improvement and the standard deviation using a two-sided test were used. For a power of 0.8, it was estimated that 48 participants would be needed to detect a true result. This was increased to a power of 0.9, requiring 65 participants to account for dropout.

Analysis plan: Latent class growth analysis (LCGA), linear mixed models, structural equation modelling by way of cross lagged panel models (CLPM) and bivariate correlation analysis will be performed. Bivariate analysis performed using JMP Statistical Software with the remaining analysis performed using Statistical Analysis System (SAS) Base Version 9.4 with the level of statistical significance set at p<0.05.

Recruitment
Recruitment status
Active, not recruiting
Date of first participant enrolment
Anticipated
Actual
23/08/2018
Date of last participant enrolment
Anticipated
Actual
15/10/2021
Date of last data collection
Anticipated
31/05/2024
Actual
Sample size
Target
65
Accrual to date
Final
112
Recruitment in Australia
Recruitment state(s)
VIC

Funding & Sponsors
Funding source category [1] 316228 0
University
Name [1] 316228 0
La Trobe University
Country [1] 316228 0
Australia
Primary sponsor type
University
Name
La Trobe University
Address
Country
Australia
Secondary sponsor category [1] 318413 0
None
Name [1] 318413 0
Address [1] 318413 0
Country [1] 318413 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 315047 0
La Trobe University Human Ethics Committee
Ethics committee address [1] 315047 0
https://www.latrobe.edu.au/researchers/research-office/ethics/human-ethics
Ethics committee country [1] 315047 0
Australia
Date submitted for ethics approval [1] 315047 0
08/06/2018
Approval date [1] 315047 0
03/08/2018
Ethics approval number [1] 315047 0
HEC18260

Summary
Brief summary
The low FODMAP diet is an effective symptom management approach for 50-75% of individuals with irritable bowel syndrome (IBS), leaving 25-50% as non-responders. Determining predictors of treatment response at the individual level during all three-phases of the low FODMAP diet are lacking. The aim was to investigate predictors of symptom response to the low FODMAP diet in patients with IBS.
Adult IBS participants undertook the low FODMAP diet via one-on-one dietetic education including elimination, reintroduction and personalisation phases. Predictor variables included levels of depressive, anxiety, and extraintestinal somatic symptoms, stress, treatment beliefs and expectations, behavioural avoidance, and illness perceptions. Symptom severity and quality of life were the outcome variables. Questionnaires assessing psychological predictors, symptoms and QoL were completed at five timepoints: pre-dietitian (week 0), immediately post-dietitian, at the end of the elimination (week 5), reintroduction (week 13) and personalisation (week 25) phases. Statistical analyses will assess the predictive relationships between psychological predictors and symptom severity.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 133518 0
Dr Jessica Biesiekierski
Address 133518 0
Monash University, Department of Nutrition, Dietetics & Food, Level 1, 264 Ferntree Gully Road, Notting Hill Victoria 3168, Australia
Country 133518 0
Australia
Phone 133518 0
+61399024269
Fax 133518 0
Email 133518 0
[email protected]
Contact person for public queries
Name 133519 0
Jessica Biesiekierski
Address 133519 0
Monash University, Department of Nutrition, Dietetics & Food, Level 1, 264 Ferntree Gully Road, Notting Hill Victoria 3168, Australia
Country 133519 0
Australia
Phone 133519 0
+61399024269
Fax 133519 0
Email 133519 0
[email protected]
Contact person for scientific queries
Name 133520 0
Jessica Biesiekierski
Address 133520 0
Monash University, Department of Nutrition, Dietetics & Food, Level 1, 264 Ferntree Gully Road, Notting Hill Victoria 3168, Australia
Country 133520 0
Australia
Phone 133520 0
+61399024269
Fax 133520 0
Email 133520 0
[email protected]

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
Yes
What data in particular will be shared?
After de-identification; individual participant data underlying published results.
When will data be available (start and end dates)?
Immediately following publication; no end date determined.
Available to whom?
Only researchers who provide a methodologically sound proposal.
Available for what types of analyses?
Only to achieve the aims in the approved proposal.
How or where can data be obtained?
Access subject to approvals by Principal Investigator ([email protected])


What supporting documents are/will be available?

Doc. No.TypeCitationLinkEmailOther DetailsAttachment
22077Study protocol  [email protected]
22078Analytic code  [email protected] Link to be provided once analysis is complete.
22079Informed consent form  [email protected]
22080Ethical approval  [email protected]



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.