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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]

HEC18260

Universal Trial Number (UTN)

Trial acronym

Linked study record

Health condition

Health condition(s) or problem(s) studied:

Irritable bowel syndrome

Condition category

Condition code

Oral and Gastrointestinal

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]

Treatment: Other

Comparator / control treatment

No control group

Control group

Uncontrolled

Outcomes

Primary outcome [1]

Gastrointestinal symptoms over the three phases of the low FODMAP diet

Timepoint [1]

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]

Quality of life over the three phases of the low FODMAP diet

Timepoint [2]

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]

Credibility and expectancy of treatment response over the three phases of the low FODMAP diet

Timepoint [3]

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]

FODMAP restriction

Timepoint [1]

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]

Psychological predictors of treatment response over the three phases of the low FODMAP diet

Timepoint [2]

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]

Illness perceptions as predictor of treatment response over the three phases of the low FODMAP diet

Timepoint [3]

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]

Psychological predictors of treatment response over the three phases of the low FODMAP diet

Timepoint [4]

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]

Anxiety as a predictor of treatment response over the three phases of the low FODMAP diet

Timepoint [5]

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]

Somatic symptoms as predictors of treatment response over the three phases of the low FODMAP diet

Timepoint [6]

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]

Stress as a predictor of treatment response over the three phases of the low FODMAP diet

Timepoint [7]

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]

GI-specific anxiety as a predictor of treatment response over the three phases of the low FODMAP diet

Timepoint [8]

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]

Behavioural avoidance as a predictor of treatment response over the three phases of the low FODMAP diet

Timepoint [9]

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?

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

Accrual to date

Final

112

Recruitment in Australia

Recruitment state(s)

VIC

Funding & Sponsors

Funding source category [1]

University

Name [1]

La Trobe University

Address [1]

Country [1]

Australia

Primary sponsor type

University

Name

La Trobe University

Address

Country

Australia

Secondary sponsor category [1]

None

Name [1]

Address [1]

Country [1]

Ethics approval

Ethics application status

Approved

Ethics committee name [1]

La Trobe University Human Ethics Committee

Ethics committee address [1]

https://www.latrobe.edu.au/researchers/research-office/ethics/human-ethics

Ethics committee country [1]

Australia

Date submitted for ethics approval [1]

08/06/2018

Approval date [1]

03/08/2018

Ethics approval number [1]

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

Dr Jessica Biesiekierski

Address

Monash University, Department of Nutrition, Dietetics & Food, Level 1, 264 Ferntree Gully Road, Notting Hill Victoria 3168, Australia

Country

Australia

Phone

+61399024269

Fax

[email protected]

Contact person for public queries

Name

Jessica Biesiekierski

Address

Monash University, Department of Nutrition, Dietetics & Food, Level 1, 264 Ferntree Gully Road, Notting Hill Victoria 3168, Australia

Country

Australia

Phone

+61399024269

Fax

[email protected]

Contact person for scientific queries

Name

Jessica Biesiekierski

Address

Monash University, Department of Nutrition, Dietetics & Food, Level 1, 264 Ferntree Gully Road, Notting Hill Victoria 3168, Australia

Country

Australia

Phone

+61399024269

Fax

[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.	Type	Email	Other Details
22077	Study protocol	[email protected]
22078	Analytic code	[email protected]	Link to be provided once analysis is complete.
22079	Informed consent form	[email protected]
22080	Ethical 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.

Trial Review

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Documents added automatically