SOMACROSS.2. Targeting Persistent Somatic Symptoms in Chronic Kidney Disease: A Personalized, Mechanism-Based Psychobehavioural Intervention using Single-Case Experimental Design (SOMA.CK.2)

• Applicants: Professor Dr. Tobias B. Huber; Professorin Meike Shedden Mora, Ph.D.
• Subject Area: Public Health, Healthcare Research, Social and Occupational Medicine ; Nephrology ; Personality Psychology, Clinical and Medical Psychology, Methodology
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 445297796

Background: Chronic kidney disease (CKD) is associated with persistent somatic symptoms (PSS) across all stages, significantly impairing quality of life and influencing treatment deci-sions. Although guidelines call for integrated symptom management, the mechanisms of PSS in CKD are insufficiently understood, and targeted symptom management remains an urgent unmet need. Results of first funding phase (FP1): In the mixed-methods cohort study SOMA.CK, patients with high CKD-specific symptom burden showed reduced quality of life, higher disability, greater psychological distress, less favourable symptom processing, and lower kidney func-tion. Multivariable models identified key biopsychosocial predictors within the SOMACROSS working model, including expectations, symptom-related distress, depression, physical inactiv-ity, comorbidity, chronic inflammation (suPAR), and epigenetic mechanisms. Experimental and qualitative studies confirmed the need for a targeted biopsychosocial approach. Objectives: SOMA.CK.2 aims to target modifiable mechanisms of PSS by testing a personal-ized, data-driven, mechanism-based psychobehavioural intervention across all CKD stages, and to unravel the long-term interplay between PSS, kidney function, psychosocial risk factors and biomarkers by following up the FP1 cohort and validating predictors in a new haemodialy-sis cohort. Work programme: SOMA.CK.2 combines an observational cohort with an embedded interven-tion study. The cohort study will investigate predictors of symptom burden in the FP1 non-dialysis-CKD cohort (n = 211) at 4 and 5 years, and validate them in the new haemodialysis cohort (n = 100) at baseline, 6, and 12 months. Predictors include biological factors (kidney function, comorbidity, suPAR) and psychosocial factors (expectations, dysfunctional symptom processing, behaviour, psychological distress). The intervention study applies replicated and randomized single-case experimental design (SCED) combined with ecological momentary assessment (EMA) to derive person-specific networks guiding the personalized intervention. Ten patients with high PSS (5 per cohort) will receive up to three mechanism-based psychobehavioural intervention modules targeting (1) dysfunctional symptom expectations, (2) maladaptive symptom processing, and (3) avoid-ance/physical inactivity. EMA will assess change in target mechanisms, while long-term ef-fects on PSS will be evaluated at 3, 6, and 12 months. Expected impact: SOMA.CK.2 will translate FP1 findings into practice by clarifying mecha-nisms of CKD-specific symptom burden and testing a personalized intervention. It will provide proof-of-concept for mechanism-based psychobehavioural interventions and inform future large-scale trials, thereby contributing to the overarching SOMACROSS.2 goal of developing data-driven interventions for chronic symptomatic conditions.

• DFG Programme: Research Units
• Subproject of: FOR 5211: Persistent SOMAtic Symptoms ACROSS Diseases: From Risk Factors to Modification (SOMACROSS.2)
• International Connection: Belgium
• Co-Investigator: Dr. Nicola Wanner
• Cooperation Partner: Professor Omer van den Bergh, Ph.D.