Chronic nausea and vomiting syndromes (CNVS), gastroparesis and functional dyspepsia (FD) are complex disorders. Body Surface Gastric Mapping (BSGM), a new test of gastric function, using Gastric Alimetry® (Alimetry, New Zealand) may be useful for de-escalating healthcare utilisation. This study aimed to define healthcare costs and estimate health economic impacts of implementing this test in patients with chronic gastroduodenal symptoms.
Methods
Consecutive patients at a tertiary referral centre evaluated with Gastric Alimetry were included. Frequency and cost data relating to medical investigations, hospital and outpatient presentations were evaluated. Costs of healthcare utilisation were calculated, and the potential cost savings of implementing Gastric Alimetry within a diagnostic decision-tree model were estimated.
Results
Overall, 31 consecutive patients (mean age 36.1 years; 83.9% female; predominant symptoms: nausea [83.9%], pain [61.3%], vomiting [67.7%] and bloating [35.5%]) completed Gastric Alimetry testing. Repeat gastroscopy and abdominal CT rates were 29% (8/28) and 85% (11/13), respectively. Gastric Alimetry testing identified spectral abnormalities in 45.2% of patients, and symptom profiling classified a further 29.1% of patients. Median annualised cost difference after test introduction was NZ$-12,032. Estimated reductions in investigation-related costs when incorporating Gastric Alimetry into the diagnostic workflow model were approximately NZ$1,300 per patient.
Conclusions
Healthcare utilisation and confirmatory testing rates remain high in nausea and vomiting syndromes. This study presents real-world data, together with a decision-tree analysis, showing Gastric Alimetry can streamline clinical care pathways, resulting in reduced healthcare utilisation and cost.
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Introduction
Chronic nausea and vomiting syndrome (CNVS) and gastroparesis are debilitating disorders that are difficult to diagnose and manage [1]. There is a combined global prevalence of ~ 1% [2]. Although differentiated by the presence or absence of delayed gastric emptying, this distinction is controversial as gastric emptying is variable over time, correlates weakly with symptoms, and may not reflect the primary disease mechanism [3‐5]. An umbrella term of nausea and vomiting syndromes (NVS) may be used.[6] In addition, NVS overlaps with functional dyspepsia (FD), sharing common pathophysiological features including neuromuscular dysfunction and gut–brain dysregulation [1, 5].
Patients with NVS have a disproportionately high healthcare utilisation [7, 8]. Factors contributing to this include complex diagnostic pathways, high rates of hospitalisation, trial-and-error therapies, implementation of nutritional support and invasive therapies [7, 9, 10]. When diagnostic uncertainty arises, this commonly leads to a ‘process of exclusion’, which can take several years, after which patients still frequently face high rates of repeated confirmatory tests in practice. Such tests often do not contribute further to management but incur further costs [7, 8, 11].
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Body Surface Gastric Mapping (BSGM) using Gastric Alimetry is a new test of gastric function, offering novel insights into gastric disease pathophysiology [12, 13]. This test aids in phenotyping patients into likely disorders related to the gastric neuromuscular dysfunction versus gut–brain dysregulation, as well as assisting in identifying other contributing factors including vagal, sensorimotor or post-surgical mechanisms [14, 15]. Early cohort studies have indicated that Gastric Alimetry can significantly reduce costs by decreasing the need for investigations, admissions and nutritional support in NVS patients [16‐18]; however, more formal healthcare utilisation evaluations are required.
The aims of this study were, therefore, to define the healthcare utilisation and costs of patients with NVS, and to estimate the potential health economic impact of implementing Gastric Alimetry testing. Real-world data were included to inform the analysis from a cohort of patients with chronic NVS undergoing work-up including with Gastric Alimetry in Auckland, New Zealand. The hypothesis was that Gastric Alimetry would reduce diagnostic costs for patients with chronic nausea and vomiting symptoms, when seen initially by a gastroenterologist, through consideration of additional investigation costs to the healthcare system, in comparison to current standard of care.
Methods
Patient Selection
Adult consecutive patients (aged ≥ 16 years) presenting with symptoms of nausea and/or vomiting, as well as overlapping features of FD evaluated using Gastric Alimetry were included. All were under the care of specialist gastroenterologists at a single tertiary referral centre in New Zealand (Waitematā, Auckland, New Zealand) between March 2019 and March 2022. Patients were excluded if they had a diagnosis of inflammatory bowel disease. No patients had eating disorder diagnoses.
Data Collection
Demographic information, comorbidities such as depression or anxiety disorders, and medication use were collected. Baseline symptom severity and quality of life were completed with the Patient Assessment of Upper Gastrointestinal Disorders-Symptom Severity Index (PAGI-SYM), Gastroparesis Cardinal Symptom Index (GCSI), Patient Assessment of Upper Gastrointestinal Disorders-Quality of Life (PAGI-QOL), and the EuroQol Visual Analogue Scale (EQ-VAS) instruments [19‐21].
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Beginning at the patient’s index presentation to the tertiary hospital for symptoms of CNVS, data on the type and number of investigations (upper gastrointestinal endoscopy, colonoscopy, ultrasound (USS) abdominal computed tomography (CT), abdominal magnetic resonance imaging (MRI), abdominal X-rays, gastric emptying scintigraphy, barium studies, oesophageal manometry and pH impedance studies), hospital admissions, emergency department (ED) presentations for gastroenterology issues and outpatient gastroenterology appointments were recorded. To determine if the cause of admission or ED presentation was for a gastrointestinal problem, clinical note review was completed by two independent researchers with discrepancies resolved by a third. Duration of follow-up was defined as the time between the index appointment and most recent encounter. Relevant gastrointestinal abnormalities that determined diagnostic yield included structural abnormalities identified on gastroscopy (oesophagitis, duodenitis, gastric ulcers, hiatal hernias), or abnormalities identified on radiological or clinical reports of gastric emptying scintigraphy, manometry, pH impedance testing, and other tests which could reasonably explain the presenting complaint(s) of nausea and/or vomiting. In cases of repeat testing, only the first investigation per patient was used.
Alimetry Classification
Gastric Alimetry spectral analysis was evaluated according to the following major phenotypes [22]:
(i)
Gastric neuromuscular dysfunction Gastric rhythm disorder or low amplitude, indicated by Gastric Alimetry Rhythm Index (GA-RI) < 0.25, and/or BMI-adjusted amplitude < 22 μV [13]. These patients were managed as per gastroparesis guidelines [23], regardless of GET status.
(ii)
High-sustained BMI-adjusted amplitude > 70 μV [13]. Gastric outlet resistance was considered if gastric emptying was also delayed [24].
(iii)
High-frequency phenotype > 3.35 cpm. Vagal dysfunction was considered, particularly if concomitant diabetes or prior oesophagogastric surgery [14, 25].
Gastric Alimetry Symptom Profiling was evaluated according to the following major phenotypes:
(i)
Sensorimotor Symptoms correlating with gastric amplitude, suggesting a likely hypersensitivity/accommodation disorder [1].
(ii)
Post-gastric Symptoms trending upward late in post-prandial period; after the gastric meal response had peaked, indicating a likely more distal pathologies (e.g. small bowel dysmotility or other disorders) [26].
(iii)
Continuous profile Symptoms constant/do not correlate with gastric amplitude. In these patients, gut–brain axis disorders were considered if spectral analysis was normal, per the study of Gharibans et al. [27].
For this study, a spectral abnormality or continuous or sensorimotor symptom profile identified via Gastric Alimetry was considered a positive diagnostic finding.
Healthcare Utilisation
The primary outcome of this study was healthcare utilisation and associated costs of patients, arising from gastrointestinal investigations, emergency room presentations, gastroenterology clinic visits and hospital admissions. Costs of investigations and healthcare visits were supplied from New Zealand Hospital administrators Pharmac (a centralised government procurement agency), hospital costing data and radiology centres sourced from data relevant to 2023. Where a range of prices were available for a procedure, the average price was used (Table S1).
Descriptive analysis of healthcare utilisation costs was completed, with data presented as frequency and percentages or median and interquartile ranges unless otherwise specified. Annual cost of care and relative contributions from different cost sources were calculated. Average healthcare utilisation costs per patient were calculated before vs after Gastric Alimetry testing. Follow-up was adjusted for follow-up duration, and pre- and post-comparisons were compared using non-parametric Wilcoxon paired analysis. All analyses were performed in R version 4.0.3 (R Foundation for Statistical Computing, Vienna, Austria).
Health Economic Analysis
A decision tree outlining the diagnostic pathway for patients with chronic nausea and vomiting syndromes (based on the Rome IV diagnostic algorithms for gastroduodenal disorders and UEG consensus statements [28, 29]), with and without the incorporation of Gastric Alimetry, is presented in Fig. 1. A linear pathway to investigations was assumed to enable the analysis, accepting that in practice, the choice and sequence of investigations are tailored to each individual patient.
Fig. 1
Flowchart of investigations. Model of investigations in NVS, based on literature and the evaluated clinical cohort. A Standard care and B incorporating Gastric Alimetry into investigations. A linear pathway to investigations was assumed to enable the analysis, accepting that in practice, the choice and sequence of investigations is tailored to each individual patient
×
Endoscopy, radiology, and gastric emptying testing were included as the decision nodes for the decision-tree analysis as these tests have the greatest weight in informing further investigation and treatment decision making, and each represent significant healthcare expenditure. The standard care pathway was informed by the Rome IV diagnostic algorithms for gastroduodenal disorders and UEG consensus statements [28, 29], and by prior qualitative work [11]. In both pathways, patients require gastroscopy initially to ensure no structural abnormalities. In the comparative pathway, patients undergo Gastric Alimetry prior to radiological investigations as this is a less invasive test. Less expensive procedures such as blood tests and X-ray were not included in the model due to vast heterogeneity in the utilisation of these healthcare resources. Indirect costs to patients, pharmaceuticals, and nutritional support costs were not included.
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The model probabilities were populated using diagnostic yield for each investigation (number of tests identifying an abnormality divided by the total number of tests performed) in the present patient cohort. If patients underwent a diagnostic test which yielded a positive diagnosis, but subsequently required any further gastrointestinal investigation, patients ‘re-entered’ the diagnostic pathway. Rates of ‘re-entry’ after relevant tests were defined. A sensitivity analysis was conducted by populating the decision tree with the probabilities based upon diagnostic yield from an American gastroparesis cohort study [7]. Total expected costs were then calculated based on the cost of a diagnostic pathway result multiplied by the expected probability of that outcome. The sum of the expected total costs of each pathway are summarised and presented. Costs of investigations and healthcare visits were supplied from New Zealand Hospital administrators sourced from data relevant to 2023 as described above. An overall cost for cross-sectional imaging was estimated based on CT scan costs (Table S1). The cost of further tests if no abnormality was found was set at an additional estimated $2000 NZD based on the additional costs of investigations including esophageal manometry, pH impedance, lower gastrointestinal endoscopy, and barium swallow studies (Table S1).
Results
Patient Demographics
Overall, 31 consecutive patients with symptoms of nausea, vomiting, abdominal pain, and bloating under the care of a specialist gastroenterologist were evaluated with Gastric Alimetry from March 2019 to March 2022. Characteristics are detailed in Table 1, including age, sex, BMI, presenting symptoms and comorbidities. The mean age was 36.1 years (range 16–66) with a female preponderance (26/31; 83.9%). The most commonly reported presenting symptoms were nausea (83.9%), abdominal pain (61.3%), vomiting (67.7%) and bloating (35.5%). There was a significant burden of gastrointestinal symptoms in this cohort with an overall median PAGI-SYM score of patients of 2.9 out of 5 (IQR 2.4–3.2) and a median GCSI score of 3.13 out of 5 (IQR 2.6–3.6). Individual PAGI-SYM subscale scores are presented in Table S2. Patients had a median PAGI-QoL score of 2.7 out of 5 (IQR 2.2–3.2). Median EQ-VAS quality-of-life score was 59.0 out of 100 (IQR 31.5–72.0; 0 is the worst possible and 100 is the best possible).
Table 1
Baseline characteristics
Variable
n = 31
Age
36.1 ± 15.8
Sex (female)
26 (83.9%)
BMI
23.9 ± 5.4
Ethnicity
NZ European
22/31 (71.0%)
Māori
2/31 (6.5%)
Other
7/31 (22.5%)
Rome criteria
CNVS and FD
29/31 (93.5%)
FD alone
2/31 (6.5%)
Presenting symptoms at index presentation
Nausea
26 (83.9%)
Vomiting
19 (61.3%)
Abdominal pain
19 (67.7%)
Weight loss
8 (25.8%)
Stomach burn/heartburn
4 (12.9%)
Bloating
11 (35.5%)
Early fullness and satiety
3 (9.7%)
Postprandial fullness
4 (12.9%)
Comorbid anxiety and depression
Anxiety
12 (38.7%)
Depression
6 (19.4%)
Psychological comorbidities were common; 12 patients had a coexisting anxiety disorder (38.7%) and 6 a coexisting major depressive disorder (19.4). Four patients had diabetes mellitus (12.9%), and 5 patients had previous thorax or abdominal surgery (16.1%), heart and lung transplant, excision of endometriosis, high anterior resection, fundoplication and laparoscopic duodeno-jejunostomy. No patients had a diagnosis of an eating disorder.
Gastric Alimetry Testing
On average, Gastric Alimetry testing was completed 2.8 years from index interaction with the healthcare system (range 0.1–15.8 years). Gastric Alimetry spectral abnormalities were found on 14 tests (45.2%); including sustained dysrhythmia indicating likely neuromuscular dysfunction [27], high gastric frequencies [14] and high gastric amplitude [13]. Gastric Alimetry symptom profiling identified 7 patients (22.6%) with a continuous symptom phenotype in the presence of a normal spectral analysis, considered to indicate a possible disorder of the gut–brain axis [27]. An additional 2 patients (6.5%) had sensorimotor symptom profiles. In total, Gastric Alimetry had a positive finding in 23 patients (74.2%).
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Healthcare Utilisation
Median follow-up time per patient from index presentation was 4.7 years (range 1.3–17.2 years). Over 148 patient-years of follow-up, there were a total of 215 emergency department presentations, 95 hospital admissions, 147 gastroenterology consultations, 39 gastroscopies, 11 barium swallows, 14 colonoscopies, 21 ultrasounds, 24 abdominal CT, 8 MR enterography, 17 gastric emptying scintigraphy tests, 6 esophageal manometry tests and 5 pH impedance tests (Fig. 3). An additional 67 gastroscopies were performed for feeding tube placement (but have not been included in the cost evaluation as this was a therapeutic procedure). 22 patients presented to ED at least once (71.0%), and 11 patients had at least one hospital admission greater than 24 h (35.5%). Healthcare utilisation showed substantial heterogeneity, with 6 patients (19.4%) accounting for 80% of emergency room visits, 91.6% of patient admissions, and 29.2% of gastroenterology visits. Healthcare events remained substantial over time; the average number of all healthcare presentations per year was 1.4 events in year one, 0.7 in year 2, 0.4 in year 3, 0.8 in year 4 and 0.9 events in year 5 (p = 0.999; Fig. 2).
Fig. 2
Healthcare events from index presentation per patient-year of follow-up: gastroenterology consultations, emergency department presentations and inpatient admissions. Mean and standard error
×
Overall investigations undertaken are presented in Fig. 3 and the diagnostic yield of the investigations is presented in Table 2. 39 gastroscopies were conducted in the public healthcare system in 31 patients. Various pathologies was found during the gastroscopies (9/39, 23.1%): coeliac disease (n = 1), duodenitis (n = 1), esophagitis (n = 1), small hiatal hernia or gastroesophageal laxity (n = 4). Eight of 31 patients (25.8%) underwent repeat diagnostic gastroscopies with none identifying further abnormalities. 53 cross-sectional imaging studies (USS, CT, MRE) were undertaken in 23 patients (74.2%); 17 patients underwent abdominal USS, 13 patients had CT scans and 8 patients had MRE. Only 7 cross-sectional imaging studies found abnormalities (18.4%); USS identified cholecystitis in 1 patient (9.1%); four CT scans identified relevant gastrointestinal abnormalities (16.7%; cholecystitis, SMA syndrome, epiploic appendagitis, annular pancreas), MRE identified abnormalities in 2 patients (25%; large bowel malrotation, slow bowel transit). 11 patients underwent repeat CT after a prior scan had not detected an abnormality; all had no abnormalities detected on repeat imaging.
Fig. 3
Investigations performed as part of clinical care. Legend refers to the order that investigation was performed in (1st: first line index investigation)
Table 2
Diagnostic yield of conventional investigations
Investigation
Number of investigations completed without repeats (n)
Abnormality found (n)
Diagnostic yield (%)
Gastroscopy
31
9
29.0
Abdominal CT
13
4
30.8
Ultrasound
17
1
5.9
Gastric emptying scintigraphy
17
6
46.5
Colonoscopy
14
0
0.0
Barium swallow study
11
1
9.1
MR enterography
8
2
25.0
Esophageal manometry
6
2
33.3
pH impedance
5
2
40.0
Table includes excludes testing within the same patient
CT computerised tomography; MRE magnetic resonance enterography
×
Gastric emptying scintigraphy was undertaken 17 times in 15 patients and demonstrated delayed gastric emptying in 5/15 patients (33.3%) and accelerated gastric emptying in 1 patient (6.7%), identifying abnormalities in 40% of patients. In the 2 patients (13.3%) in whom, gastric emptying testing was repeated; one patient had consistent results of delayed gastric emptying, while the another showed normal gastric emptying after a previously delayed emptying test result.
Before and After Alimetry
In the current clinical cohort, the costs of all healthcare utilisation before and after Alimetry, adjusted for available follow-up time is presented in Fig. 4. The number of investigations, ED visits, clinic visits and inpatient stays per year reduced substantially after Gastric Alimetry testing, compared to pre-testing healthcare utilisation (median $12,172 NZD, IQR $6301 to $27,263 versus $839 NZD, IQR $263 to $2520; p < 0.001; Fig. 4A). This finding remained consistent when only considering the cost of ED visits, clinic visits and inpatient hospitalisations to adjust for higher investigation costs early in the natural history of disease (median $4366 NZD, IQR $1823 to $15,374 versus $504 NZD, IQR $134 to $1466; Fig. 4B). Associated cost savings per patient-year in overall healthcare utilisation including investigations were $12,032 NZD (IQR $2746 to $26,108). Associated cost savings per patient-year in healthcare visits alone were $3512 NZD (IQR $1034 to $14,706).
Fig. 4
Costs of healthcare utilisation before and after Alimetry testing. A Total healthcare utilisation costs including costs of investigations as well as emergency department (ED) visits, clinic visits and inpatient medical stays. B Costs of ED visits, clinic visits and inpatient medical stays only excluding costs of investigations. Outliers are removed from the below graph
×
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Decision Tree Analysis for Clinical Investigations
The decision tree was used to estimate the costs of a standard care pathway versus a care pathway incorporating Gastric Alimetry after gastroscopy (Table 3; Fig. 5). The diagnostic yields for the clinical investigations from the prior section were used to populate the probabilities of moving between nodes in the decision tree. ‘Re-entry’ into the pathway, defined above as patients who received a diagnosis from an investigation, but subsequently re-entered the decision tree due to further tests performed after an initial test, was 50% for gastroscopy, 75% for cross-sectional imaging, 60% for gastric emptying scintigraphy and 30% for Gastric Alimetry. The expected cost of the standard care diagnostic pathway was $5482.32 and the expected cost of a diagnostic pathway incorporating Gastric Alimetry after normal gastroscopy was $4192.81. A sensitivity analysis was undertaken where the decision-tree probabilities were populated from diagnostic yields reported by Dudekula et al. from a large US cohort of comparable patients (Table 3) [7]. On sensitivity analysis, expected costs of standard diagnostic pathway was $3893.31 per patient versus $2774.07 when incorporating Gastric Alimetry. An additional sensitivity analysis of Gastric Alimetry as the terminal test is presented in Table S3.
Table 3
Estimated costs using standard care vs Gastric Alimetry pathway
Using local diagnostic values
Standard care
Gastric Alimetry pathway
Terminal node outcome
Probability of flowchart outcome
Cost
Probability of flowchart outcome
Cost
Gastroscopy diagnostic
0.15
1384.23
0.15
1384.23
Gastroscopy is non-diagnostic, Gastric Alimetry diagnostic
0.442
$2374.23
Gastroscopy, and Gastric Alimetry are non-diagnostic but cross-sectional imaging diagnostic
0.068
$2258.71
0.03264
$3248.71
Gastroscopy, Gastric Alimetry and cross-section imaging are non-diagnostic but GES diagnostic
0.146
$4908.71
0.07
$5898.71
All prior tests are non-diagnostic, further tests needed
0.64
$6908.71
0.30
$7898.71
Expected values
$5482.32
$4192.81
Using Dudekula et al. diagnostic values
Standard care
Gastric Alimetry pathway
Terminal node outcome
Probability of flowchart outcome
Cost
Probability of flowchart outcome
Cost
Gastroscopy diagnostic
0.25
1384.23
0.25
1384.23
Gastroscopy is non-diagnostic, Gastric Alimetry diagnostic
0.56
$2374.23
Gastroscopy, and Gastric Alimetry are non-diagnostic but cross-sectional imaging diagnostic
0.10
$2258.71
0.03
$3248.71
Gastroscopy, Gastric Alimetry and cross-section imaging are non-diagnostic but GES diagnostic
0.59
$4908.71
0.15
$5898.71
All prior tests are non-diagnostic, further tests needed
0.06
$6908.71
0.02
$7898.71
Expected values
$3893.31
$2774.07
Probabilities used are after considering ‘re-entry’ into the diagnostic flowchart as detailed in Fig. 5
Fig. 5
Decision tree analysis of standard care vs incorporation of Gastric Alimetry. P probability. C cost in NZD. Black arrows denote decision-tree pathways. Green arrows denote ‘re-entry’ into the decision-tree pathway from an endpoint node due to repeat testing. Pi initial probability, Pre re-entry probability, Pf final probability after accounting for patient re-entry into the pathway
×
Discussion
This study aimed to define healthcare utilisation among patients with NVS in a tertiary care setting, to evaluate the diagnostic yield of associated investigations, and to estimate the potential health economic impact of implementing BSGM testing using the Gastric Alimetry system using both real-world data and a decision-tree analysis. The real-world data confirmed that NVS care constitutes a substantial healthcare burden, characterised by repeated healthcare visits and high rates of investigations. The introduction of Gastric Alimetry was associated with a substantial reduction in healthcare costs (> $10,000 NZD per patient), due principally to reduced investigations, acute care presentations and inpatient stays. The decision-tree analysis supported these preliminary findings, estimating savings of > 30% with regard to diagnostic investigations alone. This study, therefore, demonstrates the potential utility of Gastric Alimetry to reduce healthcare costs by improving diagnostic clarity.
The high rates of healthcare utilisation reported in this New Zealand study were consistent with other data, including studies from the US healthcare context [7]. Several studies have shown high rates of diagnostic testing, acute care presentations and inpatient admissions in NVS patients, which are sustained over multiple years [7, 8, 17, 30]. Investigations are often repeated in a confirmatory fashion, as again shown in the current study, with repeat gastroscopy and abdominal CT rates of 29% and 85%, respectively. Patients may, therefore, also exceed annual recommended radiation limits due to repeated medical imaging [7]. This ongoing testing occurs despite clinical recommendations in functional disorders [28] and is explained by the clinical uncertainty commonly experienced when facing distressing gastric symptoms that fluctuate in intensity. Our data again show that such repeated testing is rarely beneficial in patients with chronic gastric symptoms, but also indicates that Gastric Alimetry may act as a ‘circuit-breaker’ in this diagnostic process through a positive diagnostic yield.
Based on previous literature, US healthcare costs for NVS are expected to be higher than those described in this study [9, 31, 32]. For example, a recent detailed analysis by Chen et al., found that in gastroparesis, US healthcare costs ranged from US$34,885 to $14,396 in diabetic and idiopathic disease over the first 3 years of diagnosis [8]. Differences in cost may be in part due to the public healthcare funding model in the New Zealand context in which this study was performed. The benefits defined by this study may, therefore, be potentially amplified in the US setting, where costs of care are higher.
The results of this study indirectly support the capability of Gastric Alimetry to provide improved diagnostic accuracy in a manner that potentially informs more targeted therapy. This was also supported by a separate study by Varghese et al., in which it was shown that Gastric Alimetry aided management decisions in > 80% of patients [17]. One key advantage of this modality, as opposed to gastric emptying, is to identify underlying neuromuscular disorders, which are well established to occur in NVS, but which have previously been difficult to separate without full thickness tissue biopsies [5, 27, 33, 34]. This was recently highlighted in a study by Wang et al., demonstrating that Gastric Alimetry provided a higher yield for specific motility abnormalities that gastric emptying testing [35]. In addition, the combination of spectral and symptom-based phenotypes cover a broader range of diagnostic possibilities, including gut–brain axis disorders, sensorimotor disorders, and the sequelae of long-term diabetes [14, 15, 18]. Therefore, as demonstrated in the present decision-tree analysis, the incorporation of the test earlier in the diagnostic pathway may decrease the ongoing need for negative confirmatory diagnostic testing and trial-and-error therapy. “However, prospective data are now needed to confirm symptom improvements are associated with specific management decisions aided by Gastric Alimetry.”
A limitation of this study should also be noted that pharmaceutical and nutrition support costs were not included, as it was found these costs could not be as reliably computed in a retrospective data analysis. Nutrition costs may be particularly significant, given other recent studies showing that Gastric Alimetry may aid in the selection of patients for invasive nutrition [16, 17], by more robustly defining patient subgroups with true gastrointestinal neuromuscular disorders from those with gut–brain axis or sensorimotor disorders [18, 27]. Given the high costs of nutrition support, which may extend to hundreds of thousands of dollars per year for patients on parenteral nutrition [36], the cost savings identified in this study could, therefore, have been underestimated. For example, Varghese et al. recently reported higher average annualised cost savings of NZ$19,787 following the introduction of Gastric Alimetry in a cohort of patients in whom enteral support costs were able to be defined, and which included patients on parenteral nutrition [17]. This study also indicated that Gastric Alimetry may aid in the de-escalation of pharmacological therapy in approximately 20% of cases, potentially contributing additional savings [17]. In addition, this study occurred during COVID shutdowns which may have altered healthcare presentation frequency.
The reported data are likely to be reliable because healthcare utilisation data can be robustly retrieved, and cases were captured consecutively, and although private care episodes and general practice visits were not captured these were expected to be infrequent in the study population context. In addition, patient out-of-pocket expenses may be substantial in functional gastroduodenal disorders [9] but were not a focus of the current study. The retrospective nature of the study also meant that patient outcomes and quality of life were not assessed, as these endpoints generally require validated questionnaires that are best conducted prospectively. Pragmatic assumptions based on recent clinical guidelines were made with regard to the hypothetical linear diagnostic pathways employed in the decision-tree analysis, whereas in practice, physicians choose investigations as tailored to a specific presentation and patient context. It should also be noted that the diagnostic journey is not a linear pathway for these patients. Multiple interactions occur with the healthcare system prior to diagnosis (including blood tests, X-rays, consultations, emergency department presentations which have not been incorporated), such that a simplified decision-tree analysis was necessary to enable meaningful comparisons. Nevertheless, the linear pathway model was a reasonable assumption as it matches general guidelines for patient care pathways, and employed modifications to allow for patient re-entry into the diagnostic pathway after positive tests.
The real-world data on health economic outcomes performed on an annualised before vs after basis could have been confounded by a naturally decreasing intensity of investigations and presentations over the course of the disorder. However, previous studies have shown that NVS patients generally continue to be high healthcare users, with relatively modest reductions in care intensity over time [7, 8], such that the sharp and substantial reductions in overall healthcare utilisation reported here were likely to be meaningful. In addition, it was recognised that healthcare utilisation changes were skewed, with a minority of patients contributing most to the cost reductions, which is a common feature of health economics studies. Future studies should continue to evaluate the management changes, healthcare outcomes and health economics associated with the introduction of Gastric Alimetry as usage of the test expands internationally, including in prospective studies, and beyond specialist tertiary settings.
In conclusion, this study presents real-world data together with a decision-tree analysis of diagnostic workflows, which show that Gastric Alimetry may improve the clinical care pathway in NVS, resulting in reductions in healthcare utilisation and cost. Non-contributory or confirmatory investigations remain common practice in NVS management, contributing to iatrogenic harm through radiation exposure, but this problem can be mitigated by streamlined diagnostic pathways.
Acknowledgments
We thank the staff and patients who participated in this study.
Declarations
Conflict of interest
The authors declare that they have no conflict of interest.
Ethical approval
Ethics approval was granted by the Auckland Health Research Ethics Committee (AH1352).
Open Access This article is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License, which permits any non-commercial use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc/4.0/.
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