Wireless Motility Capsule in the Diagnosis and Evaluation of Gastroparesis or Slow-Transit Constipation
Executive Summary
Background
This Assessment concerns the wireless motility capsule, SmartPill®, which has potential use in two clinical conditions. Gastroparesis is a chronic disorder of the stomach characterized by delayed gastric emptying in the absence of mechanical obstruction. Constipation is a constellation of symptoms which include straining, hard stools, sensation of incomplete evacuation, and infrequent bowel movements.
SmartPill® is a single-use capsule that records pH, pressure, and temperature as it transits through the gastrointestinal (GI) tract. Its location in the GI tract can be determined through changes in pH and temperature. It has been evaluated for use in the diagnosis of gastroparesis and for identifying patients with a particular type of constipation called slow-transit constipation.
Objective
The objective of this Assessment is to determine whether the wireless motility capsule (SmartPill®) improves health outcomes when used in the diagnosis and evaluation of gastroparesis and constipation, in patients presenting with clinical symptoms of those conditions.
Search Strategy
MEDLINE was searched (via PubMed) using the terms "wireless motility" or "SmartPill®." The search was performed with no time limitation through April 2012, limited to English-language articles on human subjects. Review articles, consensus statements, and practice guidelines provided additional references and background information. Bibliographies from retrieved citations were reviewed to identify additional references. Manufacturers and other websites were consulted for additional references.
Selection Criteria
The Assessment focused on studies that evaluate the diagnostic characteristics of SmartPill® for diagnosis of gastroparesis and slow-transit constipation. Studies evaluating whether SmartPill® improves health outcomes were sought, but none were found.
Main Results
Diagnosis of Gastroparesis.
Four studies were found that evaluated the SmartPill® in subjects with and without gastroparesis or in relation to a reference standard. The studies all have design issues. All included healthy asymptomatic subjects, which is not the clinical population of interest. The correlation between SmartPill® results and gastric emptying scintigraphy is moderate, with the correlation coefficient ranging between 0.57 to 0.70. In one study, SmartPill® was 65% sensitive and 87% specific in identifying previously diagnosed gastroparetic subjects compared to healthy control subjects.
Diagnosis of Slow-Transit Constipation.
Three studies were found that evaluated the SmartPill® in relation to a simultaneously performed alternative method of measuring colonic transit. Two of the 3 studies included healthy asymptomatic subjects. The performance of SmartPill® in relation to the alternative method of measuring colonic transit cannot be determined from any of these studies because there was no reference standard for the diagnosis independent of either test. Thus, only the correlation or agreement between the 2 tests can be calculated. The correlation between SmartPill® colonic transit time and the alternative method ranged from 0.4 to 0.78, depending on the study and particular method of analysis. One study performed in clinically constipated subjects showed an overall agreement between SmartPill® and the radio-opaque markers method, using binary cut-off values for each test, of 87%.
There were no studies found that evaluated whether use of SmartPill® improves patient outcomes.
Author’s Conclusions and Comment
The limited body of evidence on the diagnostic characteristics of SmartPill® does reveal correlations between SmartPill® and other tests that indicate some capability to distinguish diseased from nondiseased persons. However, because of the types of subjects included in the studies, particularly healthy patients, and the lack of a reference standard for the disease of interest (slow-transit constipation) in some studies, the diagnostic characteristics of SmartPill® are uncertain.
There are no studies that ascertain whether use of the SmartPill® in addition to or instead of alternative methods of diagnosis improves patient outcomes.
Based on the available evidence, the Blue Cross and Blue Shield Association Medical Advisory Panel made the following judgments about whether the wireless motility capsule (SmartPill®) for diagnosis or evaluation of gastroparesis or slow-transit constipation meets the Blue Cross and Blue Shield Association Technology Evaluation Center (TEC) criteria.
1. The technology must have final approval from the appropriate governmental regulatory bodies.
In 2006, an ingestible capsule (SmartPill® GI Monitoring System) was cleared for marketing by the U.S. Food and Drug Administration (FDA) via a 510(k) application, with the indication for use to evaluate delayed gastric emptying. In 2009, the FDA expanded the use of the SmartPill® to determine colonic transit time for the evaluation of chronic constipation and to differentiate between slow versus normal transit constipation.
2. The scientific evidence must permit conclusions concerning the effect of the technology on health outcomes.
Gastric Emptying.
The evidence is insufficient to determine whether SmartPill® improves outcomes in patients under consideration for gastroparesis. The studies examining the diagnostic characteristics of SmartPill® have numerous limitations and biases. The studies all include healthy asymptomatic subjects, which is not the relevant patient population. The test is only modestly sensitive in detecting previously diagnosed gastroparetic subjects, but standard tests also have the same problem due to inherent variability in gastric emptying. However, the SmartPill® gastric emptying time correlates moderately with gastric emptying scintigraphy. There are no studies that link use of SmartPill® to improved patient outcomes.
Slow-transit Constipation.
The evidence is insufficient to determine whether SmartPill® improves outcomes in patients under consideration for slow-transit constipation. Studies of the SmartPill® also included healthy patients, which is not the clinically relevant population. Although some studies included clinically constipated patients, there was no reference standard for the condition of interest, slow-transit constipation. The correlation between SmartPill® and other tests of colonic transit was moderate. There are no studies that link use of SmartPill® to improved patient outcomes.
3. The technology must improve the net health outcome; and
4. The technology must be as beneficial as any established alternatives.
The evidence is insufficient to make conclusions regarding whether SmartPill® either improves the net health outcome or is as beneficial as any established alternatives for diagnosis and evaluation of either gastroparesis or slow-transit constipation.
5. The improvement must be attainable outside the investigational settings.
It has not yet been demonstrated whether SmartPill® improves health outcomes in the investigational setting. Therefore, it cannot be demonstrated whether improvement is attainable outside the investigational settings.
Based on the above considerations, the wireless motility capsule (SmartPill®) for either the diagnosis or evaluation of gastroparesis or slow-transit constipation does not meet the TEC criteria.
Full Study
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AGA; American Gastroenterological Association; American Neurogastroenterology and Motility Society; antroduodenal manometry; asymptomatic; balloon expulsion; barium defecography; capsule; colonic inertia; colonic transit; constipation; correlation; delayed; dysmotility; extrapolation; gastric emptying; gastric emptying scintigraphy; gastrointestinal; gastroparesis; GI; ingestible; motility; nondigestible; normal transit; pH; radiolabeled; radiolabelled’; radio-opaque; radiopaque; radiopaque markers; reference standard; scintigraphic; slow transit; smartpill; Spearman; total excretion time; variability; whole-gut; wireless;
