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.