Associations between illness perceptions, reported symptoms, and gastric electrophysiology in functional dyspepsia and chronic nausea and vomiting syndrome

Introduction: Illness perceptions, the cognitive and emotional beliefs patients hold about their condition, are key determinants of patient outcomes across a range of chronic health conditions. Although well-studied in several gastrointestinal disorders, their role remains poorly characterized within patients with functional dyspepsia (FD) and chronic nausea and vomiting syndrome (CNVS). This study examined the associations between illness perceptions, gastrointestinal symptoms, mental health, and gastric electrophysiology in these patients. Methods: Patients meeting self-reported Rome IV criteria for FD and/or CNVS underwent body surface gastric mapping (BSGM) using Gastric Alimetry (Alimetry, New Zealand). The standardized protocol included a 30-minute fasting baseline, 482 kCal meal, and a 4-hour postprandial recording, with concurrent symptom logging. From the BSGM data, patients were phenotyped using established rule-based criteria via the Auckland Classification. Illness perceptions were assessed using the Brief Illness Perceptions Questionnaire alongside validated psychological and quality of life metrics. Results: The cohort included 309 patients (80% female; median age= 36, 15-88) who reported highly negative illness perceptions, which were significantly correlated with worse symptomatology, quality of life, and mental health (medium-large effect sizes). Using multivariable analysis, perceived consequences and emotional responses emerged as the most robust predictors of these patient-reported outcomes. Additionally, illness perceptions significantly mediated the relationship between mental health and gastrointestinal symptoms, with large effect sizes. Associations with gastric electrophysiology were limited to BMI-Adjusted Amplitude, which was associated with poorer perceptions of treatment control and greater emotional response to symptoms. Furthermore, the Continuous Phenotype (normal spectral activity, with continuous symptoms) was associated with worse illness perceptions, including higher perceived consequences, symptom identity, concern, and emotional response, whilst the High Frequency Phenotype was associated with lower understanding. Discussion: The way patients perceive their condition is a quantifiable aspect of the illness experience that is associated with symptom burden, mental health, and quality of life in patients with FD and CNVS. The observed associations with gastric electrophysiology suggest that illness perceptions may also vary in relation to underlying patient physiology. These findings support the consideration of illness perceptions as part of multidisciplinary assessment and management, including targeted patient education and clinical interventions to address distressing or maladaptive illness beliefs.