In an open-label study that employed the GCSI to follow symptoms of gastroparesis, 29 patients underwent GES implantation over an 18-month period, with follow-up in 28 patients.44 GES resulted in clinical improvement in 50% of patients with refractory gastroparesis. The overall GCSI significantly decreased, with improvement in the nausea/vomiting subscore and the post-prandial fullness subscore, but no improvement in the bloating subscore or abdominal pain. The decrease in GCSI was greater for patients with diabetic versus idiopathic gastroparesis. Patients with the main symptom of nausea/vomiting had a greater improvement than patients with the main symptom of abdominal pain. Patients taking narcotic analgesics at the time of implant had a poorer response compared to patients who were not. In this study, 3 clinical parameters were associated with a favorable clinical response: (1) diabetic rather than idiopathic gastroparesis, (2) nausea/vomiting rather than abdominal pain as the primary symptom, and (3) independence from narcotic analgesics prior to stimulator implantation. Knowledge of these 3 factors may allow improved patient selection for GES.
A large prospective study by Heckert et al detailed marked improvements with GES and the patterns of those improvements.55 Nausea, vomiting, loss of appetite, and early satiety improved significantly with stimulator use, with a greater improvement in vomiting in patients with diabetic gastroparesis than in those with the idiopathic form. Although GES improved symptoms in 75% of all patients, patients with diabetes had a post-GES Clinical Patient Grading Assessment score that was statistically higher than the score among patients with idiopathic gastroparesis. This difference is thought to be due to the neuromolecular mechanism of diabetic gastroparesis, where blunting of the enteric nervous system may contribute to symptomatology.
Several studies have demonstrated a clinical response to GES in patients with postsurgical gastroparesis. A study by Oubre et al showed that GES led to weekly vomiting improvements as well as a reduction in total symptom severity score.57 A study by McCallum et al further demonstrated improved symptoms, quality of life, nutritional status, and hospitalization requirements.58 GES has also been shown to improve gastroparesis symptoms in pediatric populations.47,59 Thus, although not a direct indication, GES has been shown to be beneficial in various subtypes of gastroparesis.
Additionally, irrespective of gastroparesis type, the improved symptomatology with GES appears to be durable, with one study showing persistent clinical improvements up to 8 years after device placement.60 The improvements were persistent and incremental. Likewise, McCallum et al showed that continued reductions in total symptom severity scores were evident in all gastroparesis types up to 10 years after stimulator implantation.61 The success of the procedures in part comes from careful selection of patients. Clinical parameters that are associated with favorable clinical response include diabetic gastroparesis subtype, nausea/vomiting predominance, and independence from narcotic analgesics prior to stimulator placement.62
GES has also been noted to improve other patient care metrics besides symptomatology, including nutritional status, reduced need for nutritional supplementation, and improved HbA1c.63-65 Additionally, a study by Cutts et al established that health care resource utilization significantly improved at 12, 24, and 36 months following GES placement, as compared to patients receiving standard medical therapy.66 This decreased resource utilization was also reflected in decreased costs in the GES group compared with the standard care group.
