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Stein E, Berger Z, Hutfless S, et al. Wireless Motility Capsule Versus Other Diagnostic Technologies for Evaluating Gastroparesis and Constipation: A Comparative Effectiveness Review [Internet]. Rockville (MD): Agency for Healthcare Research and Quality (US); 2013 May. (Comparative Effectiveness Reviews, No. 110.)
This publication is provided for historical reference only and the information may be out of date.
Wireless Motility Capsule Versus Other Diagnostic Technologies for Evaluating Gastroparesis and Constipation: A Comparative Effectiveness Review [Internet].
Show detailsPotential Niche for WMC
WMC could improve how clinicians test for gastroparesis or slow-transit constipation because the capsule is small and can be transported to patients wherever they live. Also, the capsule does not involve any radioactive material or x-ray exposure, and can record information about pressure, transit, and location simultaneously. The manufacturer states that the device presents little risk to patients, with less than 0.1 percent or six cases out of 6,000 patients reporting capsule retention.61 Other testing modalities for gastric emptying and colonic motility assessment do not share the same characteristics as the wireless motility capsule. A number of academic centers use scintigraphy to assess gastric transit abnormalities and whole-gut motility; however, this involves radiation exposure, significant patient time requirements, and significant cost. Antroduodenal manometry assesses gastric pressure parameters but it has limited availability and is more invasive than other testing modalities; thus, clinicians more commonly use it as an investigative tool than as a clinical test. Radiopaque markers are portable and small, but require radiation exposure, access to fluoroscopy, and radiology interpretation. One of the major limitations of other modalities for testing gastric or colonic motility is they can't evaluate both transit and pressure—yet both are involved in disease pathogenesis. The wireless motility capsule has the potential to evaluate both transit and pressure simultaneously, which could allow more optimal assessment of motility than evaluation of either parameter independently. Likewise, by recording both parameters, the wireless motility capsule could potentially provide a more accurate diagnosis with less testing which would use fewer resources and enhance patient convenience. In our review of the literature, clinicians employed a wide variety of methods when using scintigraphy and radiopaque marker testing. In contrast, studies report only a single method for using the wireless motility capsule. In addition, clinicians can perform the procedure in any office with a nurse, while one needs experts at an academic center with specialized equipment and large investments of time to perform antroduodenal manometry or colonic or whole-gut scintigraphy. In this way, the wireless motility capsule may prove to be more reproducible and more standardized than some of the other testing modalities. Note that there are few prospective randomized studies of gastric scintigraphy or radiopaque markers and multiple methods of practice of these tests. Currently, clinicians only use one type of software to analyze wireless motility capsule, which may make testing more comparable between centers as well. No studies directly assessed using capsule internationally or in a community-based environment to measure this effect.
In light of this potential niche, the wireless motility capsule is becoming much more readily available in both academic and community centers. However, questions remain about the position of the wireless motility capsule in the diagnostic algorithm for suspected motility disorders such as gastroparesis and slow-transit constipation. Since patients may have more than one of these disorders causing their symptoms, identifying the co-existent disorder is an important component for better understanding and treating a patient's disease.
Some questions to consider are: Is a test with the ability to detect more than one disorder like wireless motility capsule better than existing modalities that focus in only one region? Is the wireless motility capsule equivalent to conventional testing? Is it superior? Is it more likely to establish a concrete diagnosis or guide medical therapy than conventional motility testing? Should it be used as a stand-alone test? What should be done when wireless motility capsule is normal but clinical suspicion remains?
Recommendations from the American Neurogastroenterology and Motility Society (ANMS) practice guidelines suggest that physicians can use wireless motility capsule to diagnose patients with suspected gastroparesis and slow-transit constipation, as well as more generalized motility disorders, but these are consensus guidelines. There was no specific information about when or how physicians should use wireless motility capsule. Thus, the current literature has not clearly answered these important questions.
We must also consider the potential limitations of the wireless motility capsule. The manufacturer does not recommend using the capsule for patients with severe gastroparesis because there is a possibility of capsule retention. In addition, the wireless motility capsule evaluates motility at only a single point, as opposed to antroduodenal manometry, which has multiple recording points, or scintigraphy, which looks at transit of an entire meal. One assumes that the single point of measurement is representative of motility parameters as a whole; however, this is an assumption only and not clearly established in the literature. In assessing constipation, one cannot separate patients with slow-transit constipation from defecatory dysfunction based on only colonic transit time, so one needs further motility testing like balloon expulsion or anorectal manometry, and clinical judgment to evaluate defecation. Finally, parameters of motility for a non-digestible solid are different than those for either liquids or a meal, implying that patients can have abnormalities with one modality that would not be seen with another. In short, while the potential of wireless motility capsule testing is exciting, many questions remain as to whether it is equivalent or superior to other modalities. And its appropriate place in the diagnostic algorithm is still unclear.
Key Findings and Implications
Few studies met our criteria for evaluation. The paucity of full-length articles with independent data limited our ability to answer the Key Questions definitively.
Key Question 1. Evaluation of Gastric Dysmotility: WMC Alone Versus Other Diagnostic Tests
WMC Versus Scintigraphy
We found low strength of evidence from seven studies12,16,34,41,43-45 to support that wireless motility capsule is comparable with gastric scintigraphy in diagnostic accuracy. The sensitivity was moderately greater in some studies, but they reported slightly lower specificity. The test agreement and diagnostic gain were moderate. Diagnostic agreement between wireless motility capsule and gastric scintigraphy ranged from 58 to 86 percent for positive test agreement and from 64 to 81 percent for negative test agreement.
We found low strength of evidence from five studies16,34,41,43,45 that transit data obtained via wireless motility capsule testing correlate well with scintigraphic gastric emptying. The reporting of the results in these studies was heterogeneous. One study reported a correlation coefficient of 0.73 between gastric emptying time measured by the wireless motility capsule and 4-hour gastric emptying measured by gastric scintigraphy.16 When comparing wireless motility capsule with gastric scintigraphy, one should keep in mind that wireless motility capsule measures emptying of an indigestible object after the emptying of a meal, while gastric scintigraphy measures emptying of a meal. In a sense, then, wireless motility capsule indirectly measures what gastric scintigraphy measures. Good correlation between the two tests indicates that delayed meal emptying generally translates into delayed indigestible object emptying. Other studies reported sensitivity, specificity, and device agreement between wireless motility capsule transit data and gastric scintigraphy.34,43,45 All three studies examining transit time showed similar sensitivity and specificity for wireless motility capsule and scintigraphy, and some studies reported increased diagnostic gain of sensitivity with wireless motility capsule.
Low strength of evidence from two studies supports the utility of wireless motility capsule versus scintigraphy in measuring pressure profiles.43,45 Wireless motility capsule reports pressure patterns, but scintigraphy can not detect pressure patterns. It does appear, however, that abnormalities are more likely to be seen with wireless motility capsule than scintigraphy, especially if one adds assessing pressure patterns to the equation. However, based on the literature, there remain questions as to whether increased diagnostic detection has clinical implications.
Low strength of evidence supports how testing with wireless motility capsule versus scintigraphy might change treatment. Three studies identified change in treatment.12,34,44 Wireless motility capsule was associated with a change in management ranging between 50 and 69 percent of patients, change in medication in 47 to 82 percent of patients, and change in diet in 11 to 27 percent of patients. Since scintigraphy is the reference standard, physicians would likely make all decisions based on clinical symptoms and scintigraphy testing. There was low quality evidence suggesting that wireless motility capsule is comparable with scintigraphy in informing a change in management. Although Kuo et al.12 reported that a large percentage of patients in their study avoided testing, they accepted the results of the individual test as definitive and elected not to pursue additional testing. The authors suggested that the best way to study the comparative effectiveness of these diagnostic modalities would be to randomize subjects to receive care guided by either wireless motility capsule or reference standard testing (which could be uniformly applied), and then assess outcomes (including the need for additional tests) using blinded reviewers.
There is low strength of evidence regarding harms from wireless motility capsule as compared with scintigraphy. Many articles mentioned harms, but overall the articles did not report any serious adverse events, deaths, bowel obstructions, or rehospitalizations in patients using the wireless motility capsule or gastric scintigraphy. A measurable portion of the study participants who received the wireless motility capsule reported minor symptoms such as nausea, abdominal discomfort, or bloating. Studies noted loss of data capture or device failure; however this does not seem to qualify as a true harm.
Overall, we had graded the strength of evidence for many outcomes addressing Key Question (KQ) 1 to be low because we considered the evidence to have medium risk of bias, consistent reporting, direct nature of the data, and imprecise findings. The main limitation weighting the risk of bias was that the studies did not prespecify enrollment of patients or enroll them randomly; in fact many studies did not report how they selected patients for testing and study. Another limitation was the lack of advance prespecification of criteria and values of positivity of the tests being used. The final major limitation was that few studies mentioned whether they selected a person without conflict of interest to manage the data collected. Most studies had limited followup duration, which hampers our ability to draw conclusions about some of the outcomes that are really important to patients. A major strength of the full-length articles was that there was independent review of the results in the analysis.
We could not conduct a meta-analysis because of the heterogeneity of the data and patient populations in the studies. Our ability to compare studies was limited by lack of consistency in how the studies defined reference standards. The reference standard the studies commonly used was community based gastric scintigraphy testing performed within 2 years of enrollment into a study. Local standards for scintigraphy vary greatly, and this introduced heterogeneity into the patient populations under investigation. Many studies had different definitions for key outcomes such as diagnostic agreement, sensitivity, and specificity, as well as different diagnoses based on similar test results. We can explain this latter discrepancy by the fact that cut off values for detecting gastroparesis with wireless motility capsule have changed over time. It is uncertain if the available examinations of motility testing captured the full spectrum of patients, as academic referral centers were the primary recruitment site for studies. Overall, seven studies with 560 patients addressed the question of diagnostic accuracy.12,34,41-45 For a rare illness, the large number of patients included for evaluation reflects the great length that researchers have taken to assess the quality of this modality. Several studies suggested there was some diagnostic gain with wireless motility capsule as compared with scintigraphy, assuming all additional cases identified were correct and not false positives.12,16,34,43,45 Employing simultaneous scintigraphy and wireless motility capsule at the time of assessment, the investigators attempted to minimize the impact of having a heterogeneous population. Sensitivity and specificity for both scintigraphy and wireless motility capsule compared with symptoms in these studies is expectedly low given the issues above and the fact that the denominator may not have truly reflected entirely gastroparetic patients. Device agreement is a more useful parameter to measure in these papers than sensitivity and specificity.36 However, agreement is likely to be imperfect because these two modalities look at different mechanisms of transit.
Regarding treatment decisions, we did find that, in three studies, wireless motility capsule testing altered the management of patients with suspected gastroparesis (50 to 69 percent change in management for medicine, diet, or surgery). However, the strength of evidence was low (i.e., likely to be changed by future evidence).
The evidence was insufficient to draw conclusions regarding the differences or similarities between gastric scintigraphy and wireless motility capsule with regards to patient-centered outcomes or resource utilization. Very little research examined resource utilization, and no studies specifically examined this outcome with any rigor.
The findings reported in the literature are consistent with what would be expected based on the pathophysiology of gastroparesis and the comparative methods of wireless motility capsule and gastric scintigraphy. Comparing scintigraphy with wireless motility capsule is fundamentally a challenging endeavor. Both modalities evaluate different parameters. Scintigraphy looks at transit of a test meal and does not assess pressure. When the stomach processes a meal, fundic accommodation is followed by antral contractions that break up the food into small particles that are then propelled from the antrum to the duodenum. In comparison, the wireless motility capsule is not digested and is believed to exit the stomach when the gastric motility patterns change from a fed to fasting state and migratory motility complexes resume. As such, these two technologies are evaluating different parameters and a direct comparison may be challenging if one looks at transit alone.
WMC Versus Antroduodenal Manometry or Endoscopy
No head-to-head comparison of antroduodenal manometry (which can record pressure patterns) and wireless motility capsule was found in patients with suspected gastroparesis in our review. This makes it difficult to make a more definitive assessment of the ability of wireless motility capsule to detect abnormalities in pressure patterns in our defined populations. Similarly, we did not find any studies that compared wireless motility capsule testing with endoscopy among patients with suspect gastroparesis.
Key Question 2. Evaluation of Gastric Dysmotility: Wireless Motility Capsule in Combination With Other Diagnostic Tests Versus Other Diagnostic Tests Alone
Wireless Motility Capsule Plus Gastric Scintigraphy Versus Gastric Scintigraphy Alone
Two studies34,45 assessed the incremental value of using the wireless motility capsule with gastric scintigraphy. We found low strength of evidence to suggest that wireless motility capsule is associated with modest improvement in diagnostic accuracy over use of scintigraphy alone for patients with suspected gastroparesis. We also found low strength of evidence to support the incremental benefit of wireless motility capsule in evaluating transit times and pressure patterns. The two studies that did attempt to address this question had a method of data collection that may not have allowed for full understanding of diagnostic discrepancy. Discrepancy is when one test shows disease and the other test does not show disease. The authors assumed that a discrepancy with results (when wireless motility capsule was positive but scintigraphy was not) was always a diagnostic gain in a population of patients with gastroparesis.34 This assumption is difficult to confirm without having an independent gold standard for establishing the diagnosis.
While few studies addressed this question specifically, the ones that did were among the better studies in terms of quality, and demonstrated independent review of the wireless motility capsule and scintigraphy. We assessed risk of bias as medium and we felt these studies were consistent and direct. We felt precision was low but this is difficult to gauge for this question. The overall strength of evidence was low for this Key Question. It is very hard to prove an incremental benefit of the test when clinicians use it in addition to other testing modalities because it is hard to determine how studies performed clinical decisionmaking. It may be unclear which test the clinician used to form an opinion of the case, and it may be unclear how much the incremental information contributed to the decisionmaking process. The retrospective nature of studies also limited the strength of evidence.
In addition, understanding the incremental benefit of wireless motility capsule when added to gastric scintigraphy should take into account the fact that eligibility criteria for these studies required a previous positive test for gastric emptying scintigraphy and documented gastroparetic symptoms. Therefore, the addition of wireless motility capsule testing showed incremental sensitivity over scintigraphy testing alone in this population, which one should take into account when judging these results' clinical applicability.
The incremental benefit for wireless motility capsule when assessing suspected gastroparesis is consistent with the nature of the disorder and the tests, since the wireless motility capsule offers pressure data and motility data which are not discernible by scintigraphy alone, as well as lower gastrointestinal motility data which can help explain symptoms in patients with combinations of motility disorders. Additional reported information in combination with scintigraphy can add measurable benefit, especially with regard to identifying a more diffuse motility disorder. The evidence was limited and there was no information to guide any conclusions regarding treatment decisions, utilization, patient-centered outcomes, or harms when evaluating the incremental value of also using wireless motility capsule testing.
Incremental Value of Wireless Motility Capsule Compared with Antroduodenal Manometry Alone or Endoscopy Alone
We did not find any studies that evaluated the incremental value of adding the wireless motility capsule test to either antroduodenal manometry or endoscopy in patients with suspected gastroparesis.
Key Question 3. Evaluation of Colonic Dysmotility: Wireless Motility Capsule Alone Versus Other Diagnostic Tests
Wireless Motility Capsule Versus Radiopaque Markers
The strength of evidence was low from five studies containing 306 patients comparing wireless motility capsule with radiopaque markers in terms of their accuracy in diagnosing slow-transit constipation.12,17,32,34,48 The diagnostic accuracy of the wireless motility capsule was similar to radiopaque markers (concordance was about 80 percent in three of the larger studies). Sensitivity and specificity were 46 and 95 percent for wireless motility capsule compared with clinical constipation, and 37 and 95 percent for radiopaque markers.17 The wireless motility capsule was comparable with radiopaque markers in assessing diagnostic accuracy, and matched the sensitivity in different target populations in a reliable way.
The strength of evidence was low to suggest a strong correlation between the colonic transit time estimated by wireless motility capsule versus radiopaque markers. The correlation coefficients between these two measures ranged from 0.69 to 0.71.
The strength of evidence was low regarding the effect of wireless motility capsule testing on treatment decisions based on radiopaque marker testing. We graded the strength of evidence as low because only two retrospective chart reviews offered information about change in management for the wireless motility capsule compared with use of radiopaque markers.12,34 These two studies differed in the patient populations and the reporting of the outcomes. One of the studies reported few events, providing imprecise results. The data were further limited because not all patients underwent both diagnostic tests of interest. We found low strength of evidence that wireless motility capsule can affect resource utilization.
The strength of evidence was low in the five studies reporting on harms relevant to wireless motility capsule or radiopaque markers.17,32,34,46,48 Studies infrequently reported harms and adverse events for the wireless motility capsule or radiopaque markers. The wireless motility capsule is comparable to radiopaque markers with regard to low frequency of harms, as studies did not report any serious adverse events or mortality. Radiopaque marker testing involves exposure to at least one x-ray. A small proportion of patients who received wireless motility capsule required day 21 x-ray (by protocol) if the capsule had not spontaneously passed; in practice, patients might not require x-ray assuming they witness capsule passage or are asymptomatic. Studies reported technical failures in prototype devices with rates between 3 and 10 percent, depending on the study.17,48 Other harms or adverse events reported included dysphagia, abdominal discomfort, bloating, or nausea, which happened infrequently. These all resolved spontaneously.32
The strength of evidence was insufficient to make any conclusions about patient-centered outcomes like symptom improvement, quality of life, and patient satisfaction. No included studies addressed these outcomes of interest. These are difficult outcomes to assess without using dedicated symptom scores or mining large sources of data on hospital and physician visits. We will also need longer duration studies to address questions about change in quality of life or symptoms, which requires assessment along multiple time points.
Many factors contributed to our giving an overall grading of low strength of evidence for comparing the diagnostic accuracy of wireless motility capsule versus radiopaque markers in assessing slow-transit constipation (KQ 3). We felt the evidence had a moderate risk of bias because many of the studies were small, prospective, cohort studies that lacked randomized patient selection, did not report if there was blinding of assessment, and often did not apply the same reference standard to all the patients. Furthermore, many studies recruited patients from academic referral centers and it is uncertain if they captured the full spectrum of patients. Most studies had limited followup duration, which hampered our ability to draw conclusions about some of the outcomes that are important to patients, such as patient satisfaction or change in symptom scores. We had only imprecise estimates of the effects on treatment decisions and harms. The way studies defined non-reference standards limited our conclusions. In several of the studies the non-reference standard test was a community based radiopaque marker study of varying protocol. The multiple protocols had different assessment methods, which could have influenced the results. We could not conduct a meta-analysis because of the heterogeneity of reported data and patient populations in the studies. Although the strength of evidence was low, it is impressive how well these devices correlated, given the studies' limitations.
Much like the comparison between scintigraphy and wireless motility capsule, radiopaque markers and wireless motility capsule assess different components of transit. Some of the points of assessment coincide and provide comparable data, but the additional pressure and transit data offered by the wireless motility capsule make it a different modality. With the high level of diagnostic agreement between radiopaque markers (the non-reference standard) and wireless motility capsule for diagnosing slow-transit constipation, one may be able to use wireless motility capsule instead of radiopaque markers. More evidence will help to strengthen the support for this type of use and define which populations would gain the most benefit from one test versus another. Overall, the studies showed diagnostic agreement between wireless motility capsule and radiopaque markers for assessing and diagnosing slow-transit constipation.
Wireless Motility Capsule Versus Colonic Scintigraphy
We found no evidence to evaluate the wireless motility capsule in comparison with colonic scintigraphy in patients with suspected slow-transit constipation. We excluded studies on scintigraphy from our analysis because they compared testing in healthy subjects separately from those with constipation or slow-transit constipation and thus were not eligible for inclusion.
Key Question 4. Evaluation of Colonic Dysmotility: Wireless Motility Capsule in Combination With Other Diagnostic Tests Versus Other Diagnostic Tests Alone
No studies directly addressed any outcomes of interest related to KQ 4. The main clinical use of wireless motility capsule was determined by consensus to be a replacement test. However, there are also patients with indeterminate test results for whom physicians will recommend wireless motility capsule. Is the combination of tests more definitive than one test alone? What is the added benefit of the detection of other gut motility abnormalities when assessing colonic transit? If wireless motility capsule also finds gastric emptying delay, should we consider this a diagnostic gain? Many of the studies counted these additional diagnoses as a diagnostic gain, since wireless motility capsule is also comparable to gastric scintigraphy in detecting gastric emptying delay. While there is evidence of concordance between tests, there is little data about the timing of these tests in a diagnostic workup. The design of the studies was to define the role of wireless motility capsule as a possible replacement for other tests, and not to show its use in combination with other tests. The little data that were available from small trials about these outcomes were heterogeneous and did not specify the nature of the patient populations of interest, therefore it was impossible to generalize based on these data. One could assess the incremental value of a new technology by diagnostic gain. However, when trying to judge whether a new test can be a replacement or adjunct to an old test, it is difficult to get a clear picture of which test was most helpful in making a diagnosis without a blinded comparison or without follow up that can assess the validity of the diagnosis and/or treatment effects over time. There are statistical techniques that one can use to do this type of analysis, but the studies did not report the data in sufficient detail to perform the calculations.
Applicability (For All Key Questions)
The applicability of the literature is limited since all studies took place in referral centers and there was no prospective testing of the wireless motility capsule as a diagnostic tool in patients with suspected disease (all included studies involved patients with known disease). When a study used a comparison group without constipation or gastroparesis, it included “healthy” controls, instead of patients who may have similar presenting symptoms who do not have constipation or gastroparesis. These controls tended to be college-aged men, compared with middle-aged females with suspected disease. Additionally, it is unclear how previous treatments or comorbidity, including diabetes, affect test performance or how the test results ultimately affect management.
Limitations and Strengths of our Review Process
Our review had three major limitations:
- No standards exist in the field of motility assessment for determining the minimum improvement of diagnostic accuracy that will identify one test as superior to another test. There are also no standards to establish the equivalence of motility tests. We arbitrarily chose a 10 percent difference in sensitivity or specificity as a potentially important difference between tests.32 We felt this threshold was a conservative minimum improvement over a reference standard with moderate diagnostic accuracy (between 50 and 80 percent). If the reference standard had a larger diagnostic accuracy (90 percent or greater), a 10 percent absolute difference is too large to expect.
- We excluded studies that only enrolled non-diseased participants as our review focused on studies that compared the diagnostic accuracy of the tests for patients with gastroparesis or slow-transit constipation. We recognize that many of the most commonly cited studies in the field included non-diseased participants.18,19,62-75 Thus, we excluded a number of studies that evaluated characteristics of the wireless motility capsule.
- Experts in the field believe that scintigraphy and radiopaque markers have imperfect diagnostic accuracy. There are several options to account for the imperfection of the reference standard.76 We chose to incorporate two of these in our review. (1) We presented the results as if the reference standard had no measurement error and acknowledged this imperfection. (2) We present concordance of the test results when available. We did not attempt to adjust the results to correct for the measurement error. This adjustment would have required assumptions that we did not have sufficient data to justify. Another option is to examine patient outcomes according to the wireless motility capsule. We had included patient outcomes (e.g., need for medications, additional tests) in our review. Unfortunately, we found few studies evaluating these outcomes.
The major strength of our review process was its comprehensiveness. We included abstracts, contacted industry for unpublished studies, and contacted study authors for missing data.
Limitations of the Identified Literature
Our aim was to compare the wireless motility capsule versus other testing modalities in terms of accuracy in diagnosing and managing gastroparesis and slow-transit constipation. The literature limited our ability to answer our Key Questions for several reasons:
- No study directly addressed the incremental value of using the wireless motility capsule in addition to using a radiopaque marker or scintigraphy in the evaluation of colonic dysmotility (KQ 4). Only limited data addressed the incremental value of using the wireless motility capsule in addition to using gastric scintigraphy, antroduodenal manometry, or endoscopy in the evaluation of gastric dysmotility (KQ 2).
- All study sites were referral centers that tend to have patients with more severe disease. The study results have limited generalizability to primary care clinics or general gastroenterology centers, which both see a greater spectrum of disease severity. The sensitivity and specificity of the wireless motility capsule may be different in referral center settings than in other settings, and the positive and negative predictive values will be different when the prevalence of disease is different.
- Many studies included non-diseased patients in the comparison of the diagnostic accuracy of the wireless motility capsule versus other tests, using a clinical diagnosis of disease as the reference standard rather than the results of the other diagnostic tests.
- The non-diseased participants had very different demographic characteristics than the gastroparesis and slow-transit constipation patients. For example, the majority of the non-diseased participants were college-aged males whereas the gastroparesis and slow-transit constipation patients were middle-aged women. Using clinical diagnosis as the reference standard, it is difficult to determine if the wireless motility capsule and other tests are distinguishing disease from non-disease or measuring differences in motility by demographic differences such as age and sex.
- Variability in the administration of the motility tests and outcome assessments may explain some of the heterogeneity in the study results. Many studies used similar protocols to perform the wireless motility capsule testing and other tests, but with slight modifications, such as in the contents of the meal. Frequently, the timing of the motility assessment differed for the wireless motility capsule and the alternative test within and between studies, which may explain differences in the test results and the diagnostic accuracy differences between studies.
- The abstracts we included did not report enough data to fully understand the study population, answer our Key Questions, or assess the quality of the studies.
- We were unable to compare the results of studies with and without industry or investigator conflicts of interest because the company that manufactures the wireless motility capsule sponsored most of the studies. The other studies did not report on conflicts of interest. No study stated that it was performed independent of industry sponsorship with authors who had no previous or current financial relationships with the manufacturer of the wireless motility capsule.
- Many studies included patients with gastroparesis defined by clinical symptoms and a prior abnormal gastric scintigraphy via local standards; however, symptoms of gastroparesis can be non-specific and many local facilities do not follow a standardized gastric scintigraphy protocol. As such, it is difficult, based on the data, to separate patients with gastroparesis from those with functional dyspepsia or other functional gastrointestinal disorders. This may have, to some degree, affected data with regards to sensitivity, specificity, and device correlation.
- We attempted to assess publication bias by contacting the manufacturer of the wireless motility capsule and requested any unpublished data, but received no response.
- Not all studies reported sufficient numbers to describe all the combinations of test results; some only provided means or medians. This hampered our ability to perform analyses, especially when analyzing combinations of tests.
- Very few studies reported on patient-centered outcomes, limiting our abilities to draw conclusions on these outcomes.
Future Research Needs
Future research should ideally emphasize a cure to these diseases that is nontoxic, cheap, easily available, and safe without major surgery or implanted devices. As far as diagnostic testing, the goal is always to find accurate, effective, inexpensive tools to diagnose or exclude cases and qualify their severity in a reproducible way, especially when treatment is expensive, unavailable, or accompanied by great risks. Studies that compare the diagnostic modalities should have blinded interpretation of the results and make every attempt to classify patients by identical criteria and standardized protocols that other centers can repeat and verify. In terms of study design, we may need multi-center trials in order to enroll patients in sufficient quantity to be meaningful. Preferably, investigators independent from the corporation that makes wireless motility capsule would lead these trials. We recommend that research focus more on prospectively studied patients in larger numbers with an appropriate spectrum of symptoms and adequate followup to determine whether the diagnosis was accurate over time. Due to the difficulty enrolling patients, carefully crafted retrospective analyses should also be considered.
We need further research to evaluate how clinicians should use wireless motility capsule in combination with or instead of other testing modalities when evaluating slow-transit constipation. The studies we reviewed used alternative measures to assess anorectal function, such as anorectal manometry, since wireless motility capsule does not capture data about this region reliably. Thus, clinicians will likely use wireless motility capsule in combination with this test.
Eventually, we need outcomes studies to see if testing helps to improve quality of life or symptom control. It is unclear at present whether a more sensitive diagnostic test might just provide lead-time bias for diagnosis but not actually change the outcomes or management steps overall for the patient. As we identify other targeted therapies, we will need to reassess the value of testing. We are aware that a new therapy is in Stage II trials for patients with diabetes and gastric emptying delay, which may increase the need for research into this area if it becomes available for use.77 Currently, most patients with nausea- and vomiting-predominant symptoms of gastroparesis receive similar first-line treatment with antiemetics or prokinetics. As treatment options for gastroparesis expand (some at great expense), then more accurate detection of disease prior to initiation of therapy may play a more prominent role in disease management. The literature did not report on resource utilization with and without using the wireless motility capsule; we will need more studies evaluating these measures.
Few data are available regarding the optimal timing of wireless motility capsule testing when diagnosing and treating patients with symptoms of possible gastroparesis or slow-transit constipation. We need to do further work to classify the types of patients within subgroups of gastroparesis or slow-transit constipation to identify severe cases that may need more urgent evaluation. Finally, little is known about whether testing should be used to assess the effectiveness of treatment or if subsequent testing would offer any benefit in long-term management of patients. Currently, symptoms and symptom resolution guide therapeutic decisions, but these require careful interpretation.
Conclusions
Based on the current literature, the wireless motility capsule appears to be accurate in detection of gastroparesis and slow-transit constipation and may provide increased diagnostic gain as compared with standard motility testing. The literature indicates that it is accessible, reproducible, standardized, emits no radiation, and is available in locations remote from academic centers (qualities which are in stark contrast to the limited availability and utility of other testing modalities in current practice). While the strength of evidence is low, the data were relatively consistent and suggested that this modality is no less sensitive than conventional testing. The evidence is insufficient to determine whether use of the wireless motility capsule will improve outcomes of care. Although we found limited evidence on the impact of WMC testing on patient outcomes, we should acknowledge that it is also true that little evidence exists on the impact of conventional motility testing.
- Discussion - Wireless Motility Capsule Versus Other Diagnostic Technologies for ...Discussion - Wireless Motility Capsule Versus Other Diagnostic Technologies for Evaluating Gastroparesis and Constipation: A Comparative Effectiveness Review
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