The role of illness perception and behaviour in the treatment of adolescents with multisystem functional somatic disorders: a post hoc mediation analysis of the AHEAD trial.
Karen H Kallesøe, Eva Ørnbøl, Kaare Bro Wellnitz et al.
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In 30 seconds
This post-hoc mediation analysis of the randomised AHEAD trial examined whether illness perceptions, illness behaviour, and psychological inflexibility mediated changes in self-perceived physical health among 91 adolescents aged 15–19 years with multisystem functional somatic disorders lasting at least 1 year. Adolescents received group-based Acceptance and Commitment Therapy or Enhanced Usual Care. At 8 months, improvements in negative illness perceptions and experiential avoidance mediated the effect of AHEAD on physical health. Mediation appeared greater at higher baseline levels of these factors, but moderation effects were not statistically significant.
Key findings
- Improvements in negative illness perceptions mediated AHEAD’s effect on self-perceived physical health at 8 months.
- Reduced experiential avoidance also mediated the effect on physical health.
- Mediation effects increased with higher baseline levels, but moderation effects were non-significant.
Why it matters
The findings suggest that changes in how adolescents interpret and respond to illness may help explain improvements in perceived physical health during psychological treatment for multisystem functional somatic disorders. These potential mechanisms can inform evaluation of treatment programmes, while the non-significant moderation results do not establish that baseline levels identify who benefits most.
What to keep in mind
This was a post-hoc mediation analysis of trial data, so the proposed mechanisms are not definitive. The analysis included 91 adolescents and assessed outcomes 3 months after treatment ended.