Introduction: Gastroparesis is a chronic condition that can lead to symptoms such as nausea, vomiting, and epigastric pain. In severe refractory cases, gastric electrical stimulation (GES) may be of benefit. Unfortunately, not all patients respond to GES. We sought to identify preoperative predictors of response based on our experience.Methods: Over 38 months we implanted GES systems in 28 patients. Therapy was initiated more than 12 months prior to this retrospective review of our prospectively maintained data in 22 patients. Three patients were lost to follow-up and 1 patient expired 4 months post-op of unrelated causes. The remaining 18 patients made up the study group. A Total Symptom Score (TSS) survey is administered to all patients at every encounter. The TSS is a 6 item survey in which common gastroparesis symptoms (vomiting severity, nausea, early satiety, bloating, after-meal fullness, and epigastric abdominal pain) are rated in the past 2 weeks on a 5 point Likert scale (0=no symptoms, 24=worst possible symptoms). All patients completed the SF-36 quality of life instrument. A failure of GES therapy was considered to have occurred when after 1 year of treatment, preoperative TSS had not decreased by at least 20%. Results: 5 patients failed to improve on multiple assessments. There were 9 patients with diabetic (DG), 6 with idiopathic (IG), and 3 with post-surgical gastroparesis (PSG) who qualified for this study. 4 non-responders suffered from IG and 1 from PSG. Review of individual items of the TSS revealed that non-responders experienced less severe vomiting pre-op (mean 0.8+/-1.3 vs. 2.7+/-1.6; p=0.03). All patients with IG and mild/no vomiting failed GES (3/3). Conclusions: In our experience, diabetic gastroparesis patients respond best to GES. Responders tend to have more severe vomiting pre-op. Pre-op quality of life, especially with regards to items measured by the MCS scale of the SF-36, correlate with response to therapy. Patients with idiopathic gastroparesis who don’t experience severe vomiting should be cautioned about a potentially higher rate of poor response to GES, and may be better served with alternative treatments. Mental health factors may play a role in patient’s perception of symptomatic response to GES. Further study is needed.

	DM	Age	BMI	Duration	TSS pre	TSS yr	MCS	PCS
Improved (13)	64%	49	27.7	15 yrs	17.4	7.6**	43.4	31.2
No response (5)	0%	42	23.7	6 yrs	15.6	14.4	26.8	32.1
p-value	<0.01*	0.49	0.45	0.2	0.32	0.10	0.01*	1.0

DM=diabetes mellitus, BMI=body mass index, MCS=mental and PCS =physical component summary scale of SF-36. *=statistically significant. **=TSS at 1 year less for responders compared to pre-op.