Gastroparesis: A Dead-end Street After All?

BACKGROUND. The aim of this study was to clarify the pathophysiology of functional dyspepsia (FD), a highly prevalent gastrointestinal syndrome, and its relationship with the better understood syndrome of gastroparesis. METHODS. Adult patients with chronic upper gastrointestinal symptoms were followed prospectively for 48 weeks in multi-center registry studies. Patients were classified as gastroparesis if gastric emptying was delayed; if not, they were labeled as FD if they met Rome III criteria. Study analysis was conducted using ANCOVA and regression models. RESULTS. Of 944 patients enrolled over a 12-year period, 720 (76%) were in the gastroparesis group and 224 (24%) in the FD group. Baseline clinical characteristics and severity of upper gastrointestinal symptoms were highly similar. 48-week clinical outcome was also similar but at this time 42% of patients with an initial diagnosis of gastroparesis were reclassified as FD based on gastric emptying results at this time point, conversely, 37% of FD patients were reclassified as gastroparesis. Change in either direction was not associated with any difference in symptom severity changes. Full thickness biopsies of the stomach showed loss of interstitial cells of Cajal and CD206(+) macrophages in both groups compared to obese controls. CONCLUSIONS. A year after initial classification, patients with FD and gastroparesis, as seen in tertiary referral centers at least, are not distinguishable by clinical and pathological features or by assessment of gastric emptying. Gastric emptying results are labile and do not reliably capture the pathophysiology of clinical symptoms in either condition. FD and gastroparesis are unified by characteristic pathological features and should be considered as part of the same spectrum of truly “organic” gastric neuromuscular disorders. CLINICALTRIALS.GOV IDENTIFIER: NCT00398801, NCT01696747