Testing a Body-functionality Intervention for Body Image in Individuals With Skin Conditions

Method of sampling/recruitment:

Recruitment from community sample, including: The University staff and student volunteers lists; Psychology undergraduate credit systems, Social media/forums; Charities; Research recruitment platforms, and a mailing lists.

Sample size:

An apriori power analysis, based on an ANCOVA, with a medium effect for the primary outcome (body appreciation) indicated a sample of 128 would be needed to achieve 80% power. Assuming an attrition rate of 50%, the total number of participants required will be 256.

In line with recommendations for evaluating interventions, we will include an internal pilot whereby we review the recruitment progress (completion) about 3 months into the trial and could then consider whether we need to make any minor or major adjustments to the recruitment strategy or study. If these substantial changes are needed, the pilot component will be written up and analysed separately to inform the next phase.

Procedure:

Time-point 1: Participants asked to read information sheet and provide consent. Participants will then be asked to complete the demographic measures and provide information on their skin condition(s). Participants will then complete baseline measures of trait body appreciation, body functionality, and, skin-specific quality of life, appearance anxiety with the order of these questionnaires counterbalanced. The online system will then randomly allocate individual meeting the exclusion criteria to either 'Expand Your Horizon' or an active control, at a ratio of 1:1. Participants will then be asked to complete the first writing activity and complete state measures

Time-point 2 (approximately 2 days later): Participants asked to complete the second writing exercise, and rate their state measures.

Time-point 3 (approximately 1 week later): Participants will be asked to complete the final writing task, before completing state measures and repeating the outcome measures given at baseline. Participants in both conditions will then be asked to provide feedback on the intervention.

Time-point 4 (One month later): Participants will be asked to repeat the outcome measures. Participants will then be shown the debrief screen and told which group they were in. Participants in the control condition will be offered a link to the intervention.

Analytic strategy:

The data will be initially assessed to check whether they meet the assumptions of the statistical tests used.

Descriptive statistics will then be used to describe the sample, and to summarise information on attrition at each point of the study and feedback on the intervention. Demographic and skin disease-history variables will be assessed for covariance using t-tests, ANOVAs and bivariate correlations as appropriate.

To assess whether randomisation of allocation to groups (intervention vs control) has been effective, t-tests and ANOVAs will be used, as appropriate, to compare demographics baseline measures.

T-tests will also be used to compare the levels of skin-specific appearance satisfaction, appearance satisfaction and body-functionality satisfaction between participants in both the intervention and control condition. This will include both intention-to-treat and completer analyses.

The effectiveness of the intervention will be tested using a series of between group ANCOVAs.

The number of participants showing reliable and clinical change on measures of anxiety and skin-specific quality of life will also be calculated for each group.

Change over time (Pre, post, one month follow up) for each group will be assessed using a repeated measures ANOVA. If any significant covariates, are identified ANCOVAs will be used instead.