Clinical classification of subgroups according to the Rome III criteria cannot be used to distinguish the associated respective pathophysiology in Japanese patients with functional dyspepsia.

OBJECTIVE Patients who meet the Rome III criteria for functional dyspepsia (FD) are generally classified into the following two subgroups, those with postprandial distress syndrome (PDS) and those with epigastric pain syndrome (EPS), in order to treat the dyspeptic symptoms caused by the respective pathophysiological conditions. However, whether simple classification of FD can accurately distinguish the pathophysiological differences between PDS and EPS remains to be clarified because the pathophysiology of FD is characterized and complicated by various factors. METHODS After classifying FD patients who were not receiving medication at the initial visit, we assessed and compared the following pathophysiological factors between the PDS and EPS groups: (1) the gastric reservoir and emptying functions using a radioisotope method (n=75), (2) the autonomic nervous system (ANS) function using electrocardiography (n=45), (3) gastric mucosal atrophy and intestinal metaplasia using histological examinations (n=47), (4) endoscopic findings of the stomach, such as superficial changes, abnormal gastroesophageal flap valves (n=67) and (5) Helicobacter pylori infection (n=48). RESULTS The FD patients exhibited higher rates of an impaired reservoir function (49.3%), gastric emptying disorders (54.7%) and relative hyperactivity of the sympathetic nervous system (31.9%) than the control subjects. However, endoscopic and histological changes of the stomach were similar in both the FD patients and control subjects. In addition, no differences were observed in the above-mentioned factors between the PDS and EPS groups. CONCLUSION The simple classification of FD patients into two subgroups according to the Rome III criteria following diagnosis does not indicate any differences in the pathophysiology related to the respective dyspeptic symptoms of FD patients.