A multidimensional model of psychobiological interactions in functional dyspepsia: a structural equation modelling approach

Objective: Gastric sensorimotor function, abuse history, 'trait' and 'state' psychological factors and 'somatisation' all play a role in functional dyspepsia (FD) and its associated impaired quality of life (QoL), but their interplay remains poorly understood. We aimed to test a comprehensive, a priori hypothesised model of interactions between these dimensions in FD. Design: In 259 FD patients, we studied gastric sensitivity with a barostat. We measured abuse history (sexual/physical, childhood/adulthood), 'trait' (alexithymia, trait anxiety) and 'state' (positive/negative affect, depression, panic disorder) psychological factors, somatic symptom reporting (somatic symptom count, dyspepsia, irritable bowel syndrome and fatigue symptoms) and QoL (physical, mental) using validated questionnaires. Confirmatory factor analysis (CFA) was used to assess whether four a priori hypothesised latent variables ('abuse', 'trait affectivity', 'state affect' and 'somatic symptom reporting') were adequately supported by the data. Structural equation modelling (SEM) was used to test the a priori hypothesised relationships between these latent variables and the observed variables gastric sensitivity and QoL. Results: Both the CFA and SEM models fitted the data adequately. Abuse exerted its effect directly on 'somatic symptom reporting', rather than indirectly through psychological factors. A reciprocal relationship between 'somatic symptom reporting' and 'state affect' was found. Gastric sensitivity influences 'somatic symptom reporting' but not vice versa. 'Somatic symptom reporting' and 'trait affectivity' are the main determinants of physical and mental QoL, respectively. Conclusions: We present the first comprehensive model elucidating the complex interactions between multiple dimensions (gastric sensitivity, abuse history, 'state' and 'trait' psychological factors, somatic symptom reporting and QoL) in FD.