Outpatient vs. Inpatient Gastric Emptying Studies: Does Admission Status Influence Findings?

Abstract

Objectives: Gastric emptying studies are performed in both outpatient and inpatient settings. Although there is no data on the prevalence of positive and negative testing between inpatient and outpatient studies, some feel inpatient testing is inappropriate secondary to potential false positives. We aim to identify the incidence and determinants of abnormal studies for inpatient versus outpatient gastric emptying studies. Methods: A retrospective chart review of scintigraphic gastric emptying studies was performed between June 1, 2012 and April 11, 2014. Demographics, clinical information, and procedure details were collected. Descriptive statistics were used to report findings with categorical variables analyzed using Pearson Chi-Square test and continuous variables analyzed with independent samples t-test. All statistical analyses were performed using IBM SPSS Statistics version 21.0 software. Results: 107 GE studies were reviewed (34 inpatient, 73 outpatient). Six incomplete studies were excluded. Mean patient age was 51 years (64% female, 60% Caucasian). There were more women than men in the outpatient population (p=0.04). The inpatient studies had a higher percentage of African Americans while the outpatient studies were mostly Caucasian (p=0.002). There were no other demographic differences between the inpatient and outpatient groups. The most common indication for testing was nausea and/or vomiting (44%). 42 (22 inpatient, 20 outpatient) tests were positive and 59 (8 inpatient, 51 outpatient) were negative for impaired gastric emptying. Inpatient GE testing was abnormal 73% of the time, while outpatient GE testing was abnormal 28% of the time (p<0.01). Review of inpatient GE studies revealed 97% patients received a medication known to alter gastric motility and 67% received opioid narcotics within 72 hours of testing. Patients with diabetes were 2.28 times more likely to have a positive test than patients without diabetes. Half of the abnormal tests were found in patients with diabetes. Conclusions: Abnormal gastric emptying studies are more commonly found in inpatient studies. A majority of inpatient studies are performed on patients who have received medications known to delay gastric motility and may be at an increased risk for false positives.