The Mediation Effect of Phobic Anxiety on the Treatment Outcome of Activity and Participation across Age: Comparison between Online and Face-to-Face Rehabilitation Aftercare of an RCT

The efficacy of internet and mobile-based interventions (IMIs) has been demonstrated with different mental health disorders, but little is known about the mediating effect of phobic anxiety on activity and participation and the differential effect of age. The current study tested a moderated mediation model with short-term change in phobic anxiety mediating between treatment (IMI vs. face-to-face, F2F) and long-term change in activity and participation, and age of patients moderating this mediation. Participants (N = 142) were recruited from psychosomatic rehabilitation clinics and randomized into the IMI psychosomatic aftercare or F2F psychosomatic aftercare. Moderated mediation analyses were conducted using R software. Results showed that the long-term treatment effects of activity and participation (β(c) = −0.18, p = 0.034; β(c’) = −0.13, p = 0.145) were improved through the successful decrease of phobic anxiety (β(a) = −0.18, p = 0.047; β(b) = 0.37, p = 0.010). Older patients benefited equally from both IMI and F2F interventions regarding short-term treatment change in phobic anxiety, while younger participants benefited more from IMI (β(Age*Treatment) = 0.20, p = 0.004). IMIs targeting mental disorders can improve activity and participation along with phobic anxiety, especially in younger individuals. The needs of older patients should be considered with the development and improvement of IMIs.