Systematic review of body image flexibility interventions
Description
This datafile comprises secondary data extracted from intervention and experimental studies that were included in a systematic review of body image flexibility interventions. The review aimed to investigate: • How effective are body image flexibility interventions for improving health outcomes in young people? • Can body image flexibility interventions offer a protective function in the context of a body image threat? • What mechanisms account for the effectiveness of body image flexibility interventions? The datafile contains extracted quantitative data (sample sizes, means and standard deviations) from 23 studies included in the review. Intervention effects were calculated as standardised mean differences (SMD) between intervention and comparison conditions: (a) no/minimal intervention control (Control) or (b) other evidence-based intervention (predominantly dissonance-based interventions; DBI). If studies included both a no/minimal intervention control and EBI, results for each are included. If there were multiple active intervention arms, the one most consistent with other studies was selected. Likewise, if studies had multiple follow-up assessments, only the final measurement was included for analysis. This data can be used to calculate SMDs for post-intervention values and/or change scores for each of the outcome variables. The SMDs can then be aggregated and analysed quantitatively based on comparisons and outcomes of interest (see further explanation in Steps to re-produce). All outcome variables are continuous measures. The SMDs presented in this datafile were derived from change scores, measured as pre-to-post change or pre-to-follow-up change as obtained directly from the original study or calculated based on pre, post, and follow-up group means and standard deviations (see below for Steps to re-produce). SMDs are presented as Hedges' g effect size (ES) with associated standard errors (SE), confidence intervals (CI), and p-values (p), which were estimated in SPSS via meta-analysis of continuous outcomes using raw data. Individual effect estimates were calculated so that a positive SMD favoured the body image flexibility intervention over comparator (Control or EBI). Our review (Brichacek et al., under review) found initial evidence to support improvements in health outcomes, protection against exposure to sociocultural body image threats, and reduction in inflexible ways of relating to one’s internal experiences relative to no/minimal intervention controls. Additionally, comparison with other evidence-based interventions, including cognitive and dissonance-based programs, suggested comparable effects. As only three studies conducted mediation analysis, it is unclear whether changes in body image flexibility and/or inflexibility explained intervention effects, highlighting an important area for future research.
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Steps to reproduce
The review was conducted in accordance with the guidelines set out in the preferred reporting items for systematic review and meta-analysis (PRISMA) statement (Page et al., 2021) and Cochrane handbook for systematic reviews (Higgins, Thomas et al., 2023). A protocol was registered with the international prospective register of systematic reviews (registration number: CRD42023481589). Sample sizes, means, and standard deviations were obtained directly from the original research articles of included studies. If the mean and distribution of change scores or baseline-adjusted values were not reported (as was for most cases), change scores were calculated using the steps outlined in the Cochrane handbook (Higgins, Li et al., 2023). Standard deviations of change scores were computed using the formula provided by Higgins, Li, et al., (2023): https://training.cochrane.org/handbook/current/chapter-06#section-6-5-2-8 (an imputed correlation coefficient of r = 0.70 was used for these calculations). For the quantitative synthesis, SMD and associated SE calculated for each outcome variable reported in individual studies were averaged to provide an aggregate effect across all assessed outcomes, as well as for select outcome domains (e.g., body image concerns, eating disorder symptoms, affect). This step was done in a separate Excel spreadsheet, and we used the averaging method described in the Cochrane handbook for this process (see Section 9.3.3; McKenzie et al., 2023). These averaged SMDs were then transferred back into SPSS, and used for the final random effects meta-analysis using pre-calculated effect size (see Method section of paper by Brichacek et al. for further details about data synthesis methods). Additional notes for users: - Data that were missing (i.e., not reported in the original study) are coded as 999.00 - The same calculation was used for measures of adaptive and maladaptive outcomes. Effect estimates for adaptive measures need to be reverse-scored so that a positive SMD favours the body image flexibility intervention over comparator. - Studies Classified as "Intervention" were those that examined changes in health outcomes following an intervention. Studies Classified as "Experimental" were those that included a body image threat induction and examined protective effects of body image flexibility training/intervention. "Pre-post" study designs (n = 1) are also reported, however, were not included in the quantitative synthesis.