
==== Front
J Am Coll Surg
J Am Coll Surg
XCS
Journal of the American College of Surgeons
1072-7515
1879-1190
Lippincott Williams & Wilkins Hagerstown, MD

38682813
JACS-2024-481
00004
10.1097/XCS.0000000000001105
3
Original Scientific Articles
Clinical Outcomes of a Large, Prospective Series of Gastric Electrical Stimulation Patients Using a Multidisciplinary Protocol
Cassidy Douglas J MD 1
Gerull William MD 1
Zike Valerie M MD 1
Awad Michael M MD, PhD, MHPE, FACS 1
From the Section of Minimally Invasive Surgery, Department of Surgery, Washington University School of Medicine, St Louis, MO.
Correspondence address: William Gerull, MD, Department of Minimally Invasive Surgery, Washington University School of Medicine, 660 South Euclid Ave, Campus Box 8109, St Louis, MO 63110. email: wgerull@wustl.edu
29 4 2024
10 2024
239 4 341346
17 2 2024
16 4 2024
22 4 2024
© 2024 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American College of Surgeons.
2024
https://creativecommons.org/licenses/by-nc-nd/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 [CCBY-NC-ND], where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal.

BACKGROUND:

Gastric electrical stimulation (GES) is an intervention used in the treatment of medically refractory gastroparesis. There are few large series demonstrating efficacy over a long-term follow-up period. This study reports clinical outcomes for patients from a single institution for up to 5 years.

STUDY DESIGN:

A prospective database of patients undergoing GES implantation for gastroparesis was collected and reviewed. Patients were selected according to a multidisciplinary institutional protocol. Baseline characteristics, including age, sex, smoking history, etiology of gastroparesis, and duration of gastroparesis symptoms, were collected. Symptomatic response was evaluated using Gastroparesis Cardinal Symptom Index (GCSI) surveys preoperatively and at subsequent follow-up visits. Other clinical outcome variables include medication use, hospitalizations due to gastroparesis, and overall satisfaction with symptom relief. Patient outcomes regarding reoperation and explantation were also recorded.

RESULTS:

A total of 157 patients have undergone GES at our institution since 2012. GCSI scores were collected in all patients at baseline, in 141 patients at 1-year follow-up, and in 110 patients at 5-year follow-up. Symptom severity in all 9 gastroparesis symptoms evaluated by the GCSI, as well as the total GCSI score, was reduced significantly at 1 year postoperatively, and these results were sustained at 5-year follow-up. Use of prokinetic and antiemetic medications was reduced during the follow-up period. Hospitalizations due to gastroparesis symptoms were also reduced. GES devices were explanted in 5 patients, 12 patients required generator exchanges, and 7 patients required reoperation due to displaced or eroded device leads during the study period.

CONCLUSIONS:

GES is associated with sustained symptomatic relief, reduced reliance on medications, and reduced hospitalizations in gastroparesis patients selected using our institutional protocol.

Gastric electrical stimulation (GES) therapy is associated with improvement in both short- and long-term symptoms and quality of life in addition to a favorable safety profile. Our study demonstrates the benefits and use of a formal multidisciplinary protocol in the selection of GES candidates to maximize benefits of sustained therapy.

OPEN-ACCESSTRUE
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pmcGastroparesis is a debilitating disease with significant morbidity and impact on the healthcare system, leading to frequent hospitalizations and emergency department visits.1,2 This chronic condition is characterized by delayed gastric emptying and the cardinal symptoms of nausea, vomiting, early satiety, bloating, and abdominal pain in the absence of mechanical obstruction. Treatment options for gastroparesis include dietary modification, pharmacologic therapy with antiemetic and prokinetic agents, nutritional supplementation, and surgical intervention. Historically, conservative medical management has had limited success in providing significant symptomatic relief. When medical management is unable to adequately control symptoms, surgical options include near-total gastrectomy, pyloroplasty, endoscopic options such as oral pyloroplasty, and gastric electrical stimulation (GES).3

GES involves the surgical placement of a gastric neurostimulator. Two leads connected to a pulse generator are implanted in the muscular layer of the stomach wall, allowing for the transmission of high-frequency, low-energy electrical pulses. Indirect stimulation of parasympathetic nerves is thought to be the mechanism by which GES improves gastroparesis symptoms. The device may be externally programmed by the provider allowing for device settings to be adjusted in accordance with the patient’s symptomatic response. The Enterra Therapy System, marketed originally by Medtronic, Inc, and now by Enterra Medical, Inc, was designated by the FDA as a device for humanitarian use in 1999 and 2000 and was approved under the Humanitarian Use Device designation for treatment of chronic, refractory nausea and vomiting secondary to diabetic or idiopathic gastroparesis.

GES has been shown to improve gastroparesis symptoms in multiple studies. A meta-analysis of 10 studies conducted from 2003 to 2011 with a total of 601 patients demonstrated significant improvement in total symptom scores and gastric emptying studies after GES therapy.4 Although most studies have been retrospective and observational, results of prospective placebo-controlled cross-over trials have demonstrated significant improvement of symptoms after 12 months of GES therapy.5,6 Few studies include both a large number of patients and a long follow-up period.7-10 Here we describe one of the largest series of GES patients with long-term clinical outcomes using a formal multidisciplinary protocol for selection of GES candidates and their subsequent management.

METHODS

A retrospective cohort review was performed of all patients who underwent GES placement at a tertiary academic medical center from January 2012 to December 2018. The end date was chosen to capture patients with at least 5-year follow-up data. Data were analyzed from a prospective, IRB-approved, database.

The diagnosis of gastroparesis was made using objective criteria. All patients, while off opioids, tetrahydrocannabinol-containing products, and glucagon-like peptide-1 agonists for 2 weeks, had evidence of delayed gastric emptying on a solid-phase gastric emptying study, defined as >10% retained meal at 4 hours. In addition, before consideration of GES placement, patients must have exhausted nonoperative management, defined as having persistent gastroparesis-related symptoms after 6 months of medical therapy. Medical therapy was defined as treatment with at least 2 classes of prokinetic and antiemetic medication as well as participation in dietary and behavioral modifications under the supervision of a registered dietician. Patients with brittle diabetes were required to be under the active management of an endocrinologist. Patients were not considered candidates for GES therapy if they had previous gastric surgery, metal allergies, a history of medical noncompliance, current tobacco use, or known need for MRI. (Note: at the time of this study, the Enterra device was not FDA-approved for use in MRI machines. This labeling has since been updated.) If patients were diagnosed with gastroparesis and severe obesity (ie BMI of more than 40 kg/m2 or more than 35 kg/m2 with associated comorbidities), they were referred to a bariatric center for a surgical weight loss procedure. All patients received insurance preapproval before proceeding with GES implantation.

Information on patient demographics and patient-reported outcomes at 1 and 5 years postoperatively was collected. Baseline patient demographics included gastroparesis etiology, results of gastric emptying study, and duration of gastroparesis symptoms. In addition, the number of hospitalizations for gastroparesis symptoms in the past year and the number of gastroparesis pharmacotherapy agents used, including prokinetic, antiemetic, and neuromodulator medications, were recorded. For each patient in the study, we reviewed all hospitalization events within our healthcare system after GES implantations. A patient was considered to be admitted for a gastroparesis-related reason if: the hospital admission included an ICD-10-CM code for gastroparesis (K31.84), their admission diagnosis included 1 or more of the cardinal symptoms of gastroparesis (eg intractable vomiting, nausea, abdominal pain), or the admission note indicated gastroparesis as the cause. Imaging was only used to rule out mechanical causes of these symptoms (eg small bowel obstruction).

Gastroparesis symptom severity was evaluated using the validated Gastroparesis Cardinal Symptom Index (GCSI) that quantifies 9 gastroparesis symptoms.11 Each symptom is scored on a scale of 0 to 5, a score of 0 indicating no symptoms and a score of 5 indicating very severe symptoms. Symptoms are grouped into 3 subscales: nausea or vomiting (comprising nausea, vomiting, and retching), bloating (comprising bloating and belly visibly larger), and postprandial fullness or early satiety (comprising stomach fullness, inability to finish a normal-sized meal, feeling excessively full after meals, and loss of appetite). The GCSI total score is an average of the 3 subscale scores, with higher scores indicating greater symptom severity. The 9-item GCSI scores were prospectively collected during in-person clinic encounters before GES placement and at 1 and 5 years postoperatively, during in-person visits as well when their devices were interrogated. Overall satisfaction with gastroparesis symptom relief was surveyed at postoperative follow-up visits using a 5-point Likert scale ranging from “very dissatisfied” to “very satisfied.” Patients were considered lost to follow-up if they could not be reached by their provided telephone number, mailing address, and electronic health record patient portal.

Preoperatively, patients were required to discontinue smoking, opioid medications, glucagon-like peptide-1 agonists, and marijuana use for at least 2 weeks before their scheduled surgery date. The GES implantation procedure was performed robotically by a single expert minimally invasive foregut surgeon. During the procedure, 2 electrodes were implanted in the smooth muscular layer of the anterior stomach wall approximately 10 cm above the pylorus. Routine intraoperative endoscopy was used to confirm correct electrode lead placement and that the gastric lumen was not entered. Electrodes were connected to a stimulator or generator (Enterra; Medtronic) that was subsequently implanted in the subcutaneous layer of the abdominal wall. Initial impedance was confirmed to be less than 800 ohms. The initial GES settings programmed were current 5.0 mA, cycle ON 0.1 seconds, cycle OFF 5.0 seconds. All other settings were nominal. The settings were first adjusted at 1 month after surgery during the first postoperative clinic visit, and then subsequently every 2 to 3 months until satisfactory clinical relief was described by the patient. If patients described little to no relief at the 1-year time point, they were considered nonresponders and were given the option of device explantation and continued management with their gastroenterologist and palliative care specialists.

Data were collected and entered into an Excel spreadsheet. Categorical data were compared using chi-square tests. Continuous data were compared using unpaired t test. Subgroup analysis was performed based on gastroparesis etiology for the idiopathic and diabetic groups; the postsurgical group was not analyzed because of the low number of patients in this group. Statistical significance was set at a p value of <0.05.

RESULTS

A total of 157 patients underwent GES placement during the study period. Of these patients, 57 (36.3%) were diagnosed with diabetic gastroparesis, 93 (59.2%) with idiopathic gastroparesis, and 7 (4.5%) with postsurgical gastroparesis. The patients were predominantly women (61.8%) with an average age of 45.3 years (Table 1). Two patients had a previous laparoscopic pyloroplasty.

Table 1. Baseline Demographics

Variable	Data (n = 157)	
Age, y, median (IQR)	45.3 (18–72)	
Sex, f, n (%)	97 (61.8)	
BMI, kg/m2, mean ± SD	25.4 ± 5.2	
Previous smoking history, n (%)	41 (26.1)	
Previous opioid use, n (%)	52 (33.1)	
Gastroparesis etiology, n (%)		
 Diabetic	57 (36.3)	
 Idiopathic	93 (59.2)	
 Postoperative	7 (4.5)	
Results of gastric emptying study		
 Delayed gastric emptying, n (%)	157 (100)	
 % retained at 4 h, mean ± SD	27.9 ± 20.8	
Duration of gastroparesis symptoms, y, mean ± SD	4.3 ± 4.1	
IQR, interquartile range.

Overall, 24 (15.3%) patients required additional procedures during the study period. A total of 5 (3.2%) patients opted for explant of their GES: 1 was explanted for an infection of the device pocket and 4 were explanted due to lack of sufficient improvement in gastroparesis symptoms. A total of 12 patients (7.6%) required generator exchanges. Seven (4.5%) additional patients required operations for mechanical issues: 3 patients due to displaced device leads and 4 patients due to lead erosion and fracture.

Patients experienced significant improvement in all 9 gastroparesis symptoms at 1 year postoperatively, and these improvements were sustained at 5 years postoperatively (Table 2). Total GCSI score also improved from 3.7 ± 1.1 preoperatively to 1.3 ± 0.7 at 1 year postoperatively. This improvement was sustained with an average score of 1.4 ± 1.1 at 5 years postoperatively. There were 16 (10.2%) patients lost to follow-up at 1 year and a total of 47 (29.9%) patients lost to follow-up at 5 years postoperatively. Patients’ overall satisfaction with gastroparesis symptom improvement was high: 87.1% of patients at 1 year and 79.7% at 5 years postoperatively were “satisfied” or “very satisfied” (Table 3).

Table 2. Comparison of Gastroparesis Cardinal Symptom Index Score Before and after Enterra Device Placement

Variable	Time since placement	
Preoperatively (n = 157)	1 y postoperative (n = 141)	5 y postoperative (n = 110)	
Nausea/vomiting subscale	3.5 ± 1.5	1.3 ± 0.7*	1.5 ± 0.8*	
 Nausea	4.0 ±1.5	1.4 ± 0.5*	1.6 ± 0.5*	
 Vomiting	3.3 ± 1.9	0.9 ± 0.5*	1.1 ± 0.5*	
 Retching	3.1 ± 1.2	1.1 ± 0.4*	1.2 ± 0.3*	
Postprandial fullness subscale	3.7 ± 1.5	1.4 ± 0.3*	1.3 ± 0.4*	
 Stomach fullness	3.7 ± 1.8	1.5 ± 0.7*	1.5 ± 0.8*	
 Unable to finish meal	3.8 ± 1.3	1.2 ± 0.5*	1.4 ± 0.5*	
 Feel full after meals	3.8 ± 1.4	1.2 ± 0.4*	1.2 ± 0.5*	
 Loss of appetite	3.4 ± 1.4	0.9 ± 0.4*	1.1 ± 0.3*	
Bloating subscale	3.6 ± 1.5	1.4 ± 0.4*	1.6 ± 0.5*	
 Bloating	3.7 ± 1.3	1.5 ± 0.4*	1.7 ± 0.5*	
 Stomach visibly larger	3.5 ± 1.6	1.2 ± 0.5*	1.4 ± 0.7*	
Gastroparesis Cardinal Symptom Index total score	3.7 ± 1.1	1.3 ± 0.7*	1.4 ± 1.1*	
Data presented as mean ± SD.

* Statistically significant difference (p < 0.05) when compared with preoperative values.

Table 3. Clinical Outcomes Before and after Enterra Device Placement

Variable	Time since placement	
Preoperatively (n = 157)	1 y postoperative (n = 141)	5 y postoperative (n =110)	
Medication use (no. of agents used in past years), mean ± SD				
 Prokinetics	1.9 ± 0.4	0.3 ± 0.1*	0.4 ± 0.2*	
 Antiemetics	2.1 ± 0.5	0.6 ± 0.3*	0.7 ± 0.4*	
 Neuromodulators	0.4 ± 0.3	0.1 ± 0.1*	0.1 ± 0.1*	
Hospitalized for gastroparesis in past years, n (%)	91 (58)	18 (12.8)*	16 (14.5)*	
No. of hospitalizations in past years, mean ± SD	3.7 ± 1.9	1.5 ± 0.4*	1.6 ± 0.4*	
% satisfied or very satisfied with gastroparesis symptom relief, mean ± SD	—	87.1 ± 12.5	79.7 ± 15.4	
* Statistically significant difference (p < 0.05) when compared with preoperative values.

Use of all 3 categories of gastroparesis pharmacotherapies was reduced at 1 year postoperatively, and these changes were sustained at 5 years postoperatively. Both the number of patients hospitalized in the past year related to gastroparesis and the amount of hospitalizations per patient in the past year were significantly reduced after GES device placement at 1 and 5 years postoperatively. Preoperatively, 91 (58%) patients had been hospitalized for gastroparesis in the past year, averaging 3.7 ± 1.9 hospitalizations. At 1 year postoperatively, patients hospitalized within the past year was reduced to 18 (12.8%), with the average number of hospitalizes reduced to 1.5 ± 0.4. At 5 years postoperatively, this reduction was sustained with 16 (14.5%) patients hospitalized within the past year with an average of 1.6 ± 0.4 hospitalizations per patient. Of note, we did not observe any difference in any of our study outcomes between the idiopathic and diabetic subgroups.

DISCUSSION

In this prospectively collected cohort of gastroparesis patients who underwent GES implantation, the majority of patients expressed sustained satisfaction with gastroparesis symptom relief and improvement in quality of life up to 5 years postoperatively. Use of gastroparesis pharmacotherapies and hospitalizations due to gastroparesis symptoms were also reduced after GES implantation. These findings suggest that GES therapy offers long-term symptom and quality-of-life improvement for gastroparesis patients with a favorable safety and tolerance profile that can reduce the overall healthcare resource use of this patient population.

Our findings corroborate the existing evidence that GES can improve nausea and vomiting symptoms in patients with gastroparesis. Our study demonstrated improvement in all 3 GCSI domains (nausea or vomiting, bloating, and postprandial fullness) at both 1 and 5 years after GES placement. Similarly, in other GES placement studies, patients report decreased vomiting frequency after immediate activation of the GES device and a prolonged response reduction at 1 year.5,12 In addition, previous GES placement studies using GCSI scores have demonstrated improvements in the nausea or vomiting domain, as well as total GCSI score, postoperatively.10,13 Contrary to our findings, Maranki and colleagues13 found that there was no improvement in GCSI subscores for bloating and abdominal pain and a more favorable response when nausea and vomiting are the primary complaints. However, multiple other studies have reported improvements in upper gastrointestinal symptoms, similar to our findings, including but not limited to anorexia, bloating, early satiety, and abdominal pain after GES implantation.14-18 Our findings, along with previously published literature, highlight the benefits that can be seen with GES in multiple symptom domains for patients with gastroparesis.

Overall, patients exhibited high satisfaction with their GES, with rates of approximately 87% and 80% satisfaction at 1 and 5 years, respectively. The high level of satisfaction at 5 years postoperatively is similar to satisfaction rates seen in other long-term GES studies and may be impacted by the favorable safety and tolerance profile of the device.9,15 Rates of device explant have been reported between 7% and 19.5% with devices removed for various reasons, including persistent symptoms, pain at the device site, mechanical issues with the device, and infection.7-9,15 Although 15.3% of patients in our cohort required an additional operation, only 3.2% of patients required explant of the device, perhaps reflecting on the safety and improved morbidity of a minimally invasive approach.3

GES therapy led to a significant and sustained reduction in all classes of medication, including prokinetic, antiemetic, and neuromodulatory medications. Previous studies have similarly demonstrated a reduction in prokinetics and antiemetics use at 1 year postoperatively for all patient groups and reduction in opioid use with GES device use.9,10 Our findings build on this work, demonstrating a long-lasting effect in medication reduction at 5 years with GES use.

Gastroparesis and chronic vomiting incur significant healthcare costs driven by repeat hospitalizations and additional economic burden from time off of work and transportation.19,20 GES can be costly—approximately $15,000 for the device and leads alone. Nonetheless, device implantation leads to a significant reduction in hospitalizations.21 Our study demonstrated a dramatic and sustained decrease in yearly hospitalizations at 1 and 5 years, greatly reducing the healthcare resources used by these patients. Similarly, Gourcerol and colleagues19 found that the healthcare costs of patients who underwent GES therapy were estimated to decline from $8,873 to $5,525 per patient per year, corresponding to a yearly savings of $3,348 per patient per year. With long-term symptom improvement of GES therapy, sustained healthcare savings outpace the cost of implementation of the device and reduce the economic burden on patients and the healthcare system.

Our institution uses a strict selection protocol for patients undergoing GES implantation. Because opioids have been shown to reduce gastric emptying and exacerbate gastroparesis symptoms, all patients are required to cease narcotic medications.22 In a study by Maranki and colleagues,13 patients taking narcotic analgesics at the time of GES placement had a poorer response compared with patients who were not. Similarly, cannabinoids have also been shown to reduce peristalsis of the gastrointestinal tract and the use of cannabinoids in patients with gastroparesis is associated with higher GCSI scores.23,24 Therefore, we require cessation of marijuana and cannabinoid products before implantation. In addition to these requirements, patients were also medically optimized by gastroenterologists, dietitians, and endocrinologists if diabetic. Using this selection protocol, we have demonstrated marked improvement in patients’ quality of life as evidenced by improved GCSI scores, overall satisfaction, and decreased medication use and hospitalizations in a large cohort of 157 patients. Most notably, this clinical improvement was sustained for a long follow-up period of 5 years. The findings of our study suggest that a formal selection protocol may ensure improved clinical outcomes in patients undergoing GES implantation for medically refractory gastroparesis.

There are some limitations to our study. This was a single-center study with all procedures conducted by a single surgeon. In addition, despite recruiting a large cohort of patients to this study, 16 patients were lost to follow-up at 1 year, and a total of 47 patients were lost to follow-up at 5 years because of inability to contact them. Admissions for gastroparesis may not have been entirely captured due to how the admission was coded. Additionally, healthcare encounters outside of our system may not have been captured in our database. The severity of diabetes mellitus was not captured for the diabetic gastroparesis etiology subgroup. In addition, severity of diabetes mellitus was not captured in the postoperative period which could influence the severity of gastroparesis symptoms. Previous work suggests that patients with diabetic gastroparesis have greater responses to GES therapy.9,13,14,25 Interestingly, we did not observe a difference in outcome between diabetic and idiopathic gastroparesis patients. Our demographic contains a majority of idiopathic gastroparesis patients. As such, our results may underestimate the true benefit of GES therapy.

CONCLUSIONS

We describe one of the largest series of patients who underwent GES therapy with long-term clinical outcomes. We demonstrate that GES therapy is associated with improvement in both short- and long-term symptoms and quality of life. Patients reported a high degree of satisfaction with their treatment in addition to objective improvements in the number of prokinetic, antinausea, and neuromodulation medications as well as hospitalizations. GES therapy has a favorable safety profile, with few device complications and a low reoperation rate. Our study demonstrates the benefits and use of a formal multidisciplinary protocol in the selection of GES candidates to maximize the benefits of sustained therapy.

Author Contributions

Data curation: Cassidy, Gerull, Zike

Writing – original draft: Cassidy, Gerull, Zike

Writing – review & editing: Cassidy, Gerull, Awad

Conceptualization: Gerull, Awad

Methodology: Awad

Drs Cassidy and Gerull contributed equally to this work.

Disclosure Information: Dr Awad has received grants from Applied Medical, Bard/BD Medical, Baxter, Ethicon, Medtronic, and Stryker for simulation training, a research grant from Intuitive Surgical, and he is a paid consultant to Ethicon, Intuitive Surgical, and Medtronic. Dr Awad’s institute is supported by funding from Intuitive Surgical. Other authors have nothing to disclose.
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