Is Gastroparesis Truly Different From Functional Dyspepsia?

Patients with functional dyspepsia (FD) and gastroparesis are commonly seen, diagnosed, and treated in gastroenterology clinics. Though we think of these diseases as two separate entities, this study aims to better understand the pathophysiology of FD compared to gastroparesis. 

Of 944 patients who had symptoms suggestive of gastroparesis over a 12-year period, 720 (76%) met the criteria for gastroparesis on scintigraphy (delayed emptying >60% at 2 hours; >10% at 4 hours), whereas 224 (24%) had normal gastric emptying study results and additionally met Rome III criteria for FD. Assessment tools used in the study included patient-reported outcomes through multiple upper gastrointestinal scoring systems and a repeat emptying study test at 48 weeks.

There was no difference in psychological or quality metrics in both groups. At 48 weeks, there was clinical improvement in 27% of the FD group and 26% of the gastroparesis group (did not vary with etiology). Interestingly, the diagnosis of gastroparesis or FD was labile over time and moved in both directions without any impact on change in symptoms. To this point, an initial diagnosis of gastroparesis was reclassified as FD in 42% of patients, based on repeat emptying results, and 37% of FD diagnoses were reclassified as gastroparesis. Finally, FD and gastroparesis shared the same characteristic neuropathology when full-thickness gastric biopsy samples were obtained in 9 nondiabetic matched control patients, which found a loss of interstitial cells of Cajal and reduced numbers of anti-inflammatory C206+ macrophages.