Helpful explanatory models for persistent somatic symptoms (HERMES): Results of a three-arm randomized-controlled pilot trial

Objective: This three-arm randomized controlled trial aimed to test the efficacy of an etiological model for persistent somatic symptoms (PSS) translated into video-animated explanatory models in comparison to a control group, and to examine additional value of personalization of the explanatory models (i.e. possibility to choose information based on mechanisms of symptom persistence). Methods: Outpatients with PSS were shown one of three 15-min video animations: a) explanatory model without personalization, b) explanatory model with personalization, c) no explanatory model control group. Changes in somatic symptom severity (PHQ-15) and psychological burden related to somatic symptoms or associated health concerns (SSD-12) from baseline to one-month follow-up were the primary outcome. Health-related quality of life (SF-12) and perceived usefulness (USE) were also assessed. Results: Seventy-five patients with PSS were allocated to the study arms (Mage = 44.2 & PLUSMN; 13.3 years, 56% female). The study arms did not differ significantly on the primary outcomes. However, no explanatory model participants reported significantly greater mental quality of life improvements than explanatory model without personalization participants (Mdiff = 7.50 [0.43; 14.56]). Further, explanatory model with personalization participants rated the individual fit of the intervention significantly higher than no explanatory model participants (Mdiff = 2.05 [0.17; 3.93]). All groups rated credibility of the intervention as very high. Conclusion: The HERMES materials seemed to have been too brief to improve symptom related outcomes. However, all three interventions were positively evaluated regarding their usefulness, particularly in case of additional personalization. Future studies should investigate potential effects of an increased intervention dose. Trial registration: DRKS00018803.