M1210 Subgroups in Functional Dyspepsia: A Cluster Analysis Approach Based On the Interaction of Symptom Severity, Gastric Sensitivity and Psychosocial Factors

Abstract

Introduction: The Rome III consensus proposed to subdivide functional dyspepsia (FD) into epigastric pain syndrome (EPS) and postprandial distress syndrome (PDS), based on the symptom pattern (Tack et al, Gastroenterology 2006). The same consensus proposed to consider separate diagnostic categories for nausea/vomiting and for belching disorders. Aim: To empirically investigate the validity of this symptom-based subgrouping. Methods: In 705 consecutive tertiary care patients, clinically diagnosed with FD according to Rome II criteria, the severity of 8 FD symptoms (pain, fullness, bloating, early satiation, nausea, vomiting, belching & epigastric burning) was scored on a Likert scale [range: 0-3 (absent, mild, moderate, severe)]. First, hierarchical cluster analysis with Ward's clustering method was used to determine the most appropriate number of clusters for subsequent non-hierarchical cluster analysis. Second, non-hierarchical cluster analysis with full seed replacement was performed to determine the optimal cluster solution. Results: The median (IQR) score was 2 (0-2) for pain & early satiation, 2 (1-3) for fullness, 2 (1-2) for bloating, 1 (0-2) for nausea, belching & epigastric burning and 0 (0-1) for vomiting. Hierarchical cluster analysis suggested a 4 cluster solution, based on the R2 method. Non-hierarchical cluster analysis with 4 clusters on all 8 variables showed very low R2 values for the variable belching, indicating that it may no be sufficiently appropriate for forming clusters. Therefore, this variable was removed from the final analysis. Non-hierarchical cluster analysis with 4 clusters on the 7 remaining variables resulted in an overall R2 of 0.37, indicating considerable overlap between the clusters. Vomiting, pain and early satiation were found to be the most important variables separating the clusters, with R2 values of 0.67, 0.54 and 0.52, respectively. The first cluster was characterized by high early satiety, fullness & bloating and moderate pain (‘postprandial distress cluster'). The second cluster was characterized by high vomiting, nausea and fullness (‘nausea-vomiting cluster'). The third cluster was characterized by high pain (‘epigastric pain cluster'). The fourth cluster was characterized by low scores on all symptoms (‘limited severity cluster'). Conclusion: The symptom-based subgroups from the Rome III criteria are supported by the present data which confirmed the existence of EPS and PDS subgroups and a nausea/vomiting cluster. On the other hand, another ‘low severity” subgroup was also identiefied and overlap between subgroups is considerable.