A pattern-based heart rate variability approach in somatic symptom disorder: Evidence from the SOMA.SSD study

Background Heart rate variability (HRV) has been proposed as a marker of autonomic dysfunction in somatic symptom disorder (SSD), but findings based on single parameters remain inconsistent. Pattern-based approaches may provide a more integrative characterization of autonomic regulation. Methods This study applied a four-pattern HRV classification (normal, low, relatively high sympathetic, relatively high vagal) in 148 patients with SSD from the SOMA.SSD cohort. Resting-state HRV was assessed using 5-min ECG recordings at baseline. Psychopathology (PHQ-15, PHQ-9, SSD-12) was assessed at baseline, 6, and 12 months. Group differences and longitudinal effects were analyzed using ANOVA and linear mixed-effects models. Results Overall, no significant differences in symptom levels were observed across the four HRV patterns groups at baseline. However, post-hoc comparisons indicated that patients with a low HRV pattern reported higher somatic symptom severity, depressive symptoms, and SSD-related distress compared to the normal HRV group. These differences remained stable over 12 months, with no significant time or interaction effects. Relatively high sympathetic and relatively high vagal patterns were not associated with increased psychopathology. Conclusions A pattern-based HRV classification is applicable in patients with SSD and highlights the clinical relevance of a low HRV pattern. This approach may support physiologically informed subtyping in psychosomatic research and could have implications for future clinical stratification.