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Stein E, Clarke JO, Hutfless S, et al. Wireless Motility Capsule Versus Other Diagnostic Technologies for Evaluating Gastroparesis and Constipation: Future Research Needs: Identification of Future Research Needs From Comparative Effectiveness Review No. 110 [Internet]. Rockville (MD): Agency for Healthcare Research and Quality (US); 2013 May. (Future Research Needs Papers, No. 27.)
Wireless Motility Capsule Versus Other Diagnostic Technologies for Evaluating Gastroparesis and Constipation: Future Research Needs: Identification of Future Research Needs From Comparative Effectiveness Review No. 110 [Internet].
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Gastroparesis
Gastroparesis is a condition in which patients experience symptoms of delayed gastric emptying in the absence of an actual physical blockage.1 The most common symptoms are nausea, vomiting, early satiety, bloating, abdominal pain, and postprandial fullness.2 Detection of gastric emptying delay is the essence of diagnosing gastroparesis. The prevalence of gastroparesis was estimated by a community-based study in 2007 to be 9.6 per 100,000 for men and 37.8 per 100,000 for women.2 Hospitalizations for gastroparesis increased by 158 percent between 1995 and 2004.3 Standard assessment for patients with typical symptoms begins with exclusion of mechanical causes of disease. Methods of testing include gastric emptying scintigraphy, antroduodenal manometry, and now wireless motility capsule (WMC) technology. Documentation of gastric emptying delay guides physicians in their recommendations for nutrition, medication, and surgical therapies.
Major outcomes of interest are assessment of motility and diagnosis of gastric emptying delay. Other outcomes include the ability of testing to influence treatment decisions such as changes in medications or nutrition, or to affect patient-centered outcomes such as symptom improvement, need for surgery, quality of life, and patient satisfaction. It is important to consider potential harms of testing such as capsule retention, radiation exposure, and mortality. Clinicians and policymakers may also be interested in the effects on resource utilization such as the need for additional tests, physician services, or hospitalizations.
Constipation
Constipation is common, occurring in 15 to 20 percent of the U.S. population.4-6 It is defined as fewer than two bowel movements per week or a decrease in a person's normal frequency of stools that is accompanied by straining, difficulty passing stool, or passage of hard solid stools.4 Patients with symptoms of constipation must be assessed by their medical history and a physical examination to exclude malignant or organic causes of constipation. For individuals who are less than 50 years of age without “red flag” symptoms, no testing is required to make a diagnosis of constipation if they meet the Rome III criteria. Clinically, patients with slow-transit constipation, also known as colonic inertia, often have the most severe symptoms of those patients with constipation, with prolonged periods of time between bowel movements. Often, standard medical therapies have failed these patients. Reported incidence of slow-transit constipation is 1 in 3000. Other studies list an incidence of 0.17 percent.7 The true incidence is likely unknown.4 Lifestyle changes and medical management should be used for all patients with symptoms of constipation. Thus, the initial evaluation of constipation symptoms does not often involve colonic transit testing. For certain individuals with suspected slow-transit constipation, colon transit testing can provide insight into the etiology of the constipation. The main diagnostic methods used to test for colonic motility are radiopaque marker examination, colonic scintigraphy, colonic and anorectal manometry, and WMC testing.8,9 The reference standard has been radiopaque markers.
Most patients with chronic constipation have improvement of symptoms with medical therapy and/or lifestyle changes. If testing confirms the presence of slow-transit constipation (colonic inertia) without use of laxatives, then surgery could be considered as a potential therapy.10 Most clinicians reserve colectomy for patients with the most terminal or untreatable conditions.
A major outcome of interest to clinicians is the ability to characterize transit time and to diagnose slow-transit constipation. Other outcomes include the ability of testing to influence treatment decisions such as change in medications or change in nutrition or to affect patient-centered outcomes such as symptom improvement, need for surgery, quality of life, and patient satisfaction. It is important to consider potential harms such as capsule retention, radiation exposure, and mortality. Clinicians and policymakers may also be interested in the effects on resource utilization such as the need for additional tests, physician services, and hospitalizations.
Objectives of the Original Systematic Review
The WMC is a new modality for diagnosing gastric and colonic motility disorders. The Johns Hopkins Evidence-based Practice Center (EPC) recently completed an Agency for Healthcare Research and Quality (AHRQ) funded systematic review of comparative effectiveness of WMC as compared with other tests for diagnosing and managing gastric and colonic motility disorders, instead of or in conjunction with other testing modalities (see analytic framework Figure 1). We also sought to define the populations that would benefit most from motility testing, including WMC testing. Overall, we showed that there was low or insufficient strength of evidence to answer most of the parts of the clinical questions we posed. A summary of the Key Questions from the review and the evidence is listed in Table 1.
Figure 1
Analytic framework of the comparative effectiveness of diagnostic technologies for evaluating gastroparesis and constipation. KQ = Key Question
Table 1
Summary of the results from the systematic review on the wireless motility capsule.
Conclusions of the Systematic Review
WMC is similar to current modalities in use for detection of slow-transit constipation and gastric emptying delay, and therefore is another viable diagnostic modality. Little data is available to determine the optimal timing of WMC in diagnostic algorithms.
Evidence Gaps in the Systematic Review
Overall, the evidence was graded as low to address the ability of WMC to detect gastroparesis or slow-transit constipation. The low strength of evidence was due to the limitations in the literature identified in the systematic review. The main limitations resulted from inconsistency in reporting on motility testing modalities. Great variation existed between methods of administration of diagnostic tests, and also in assessment of those tests. No unified standards existed to determine improvement in diagnostic accuracy. In fact, radiopaque marker testing is considered a non-reference standard, not consistent enough to be considered a gold or reference standard for assessment of slow-transit constipation. We arbitrarily chose a 10 percent difference in sensitivity or specificity for reference standards or device agreement/concordance for non-reference standards, such as radiopaque markers (ROM). Most of the “normal” subjects upon which the studies were validated were young college aged men, and most of the affected population under investigation were 50-something women.
We had excluded studies that included non-diseased participants exclusively, since our population of focus was subjects with suspected gastroparesis or constipation. Many of the studies in the literature did report on non-diseased participants, and were thus excluded. The major strength of our review was its comprehensiveness.
Little data is available to support the timing of WMC in the diagnostic and therapeutic approach to patients with symptoms of possible gastroparesis or slow transit constipation. Further work needs to be done 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.
Our aim was to compare the diagnostic accuracy of the WMC to other testing modalities to diagnose and manage gastroparesis and slow transit constipation. The identified literature limited our ability to answer our Key Questions for several reasons. We comprehensively reviewed the literature in a systematic fashion to accomplish this goal. However, we excluded studies that included non-diseased participants exclusively 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. Thus, we excluded a number of studies that evaluated characteristics of the WMC. Other limitations included the fact that few studies prospectively addressed the goal of tabulating the incremental value of WMC in addition to other modalities for diagnosis of gastroparesis or constipation. No studies appeared to definitively identify non-inferiority or superiority of a diagnostic evaluation with WMC instead of other modalities. Most of the identified studies were from major academic referral centers, which may have led to spectrum bias. The sensitivity and specificity of the WMC 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. We were unable to compare the results of studies with and without industry or investigator conflicts of interest because most studies were sponsored by the company that manufactures the WMC. 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 WMC.
- Background - Wireless Motility Capsule Versus Other Diagnostic Technologies for ...Background - Wireless Motility Capsule Versus Other Diagnostic Technologies for Evaluating Gastroparesis and Constipation: Future Research Needs
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