Magnetic Sphincter Augmentation for Treating GERD
Magnetic Sphincter Augmentation for Treating GERD
Editor’s Note: Managed care leaders are striving to make evidence-based decisions about new and emerging health technology. Managed Care and ECRI Institute have collaborated to disseminate bimonthly summaries of the Institute’s Emerging Technology Evidence Reports. ECRI Institute is an independent not-for-profit organization that researches the best approaches to improving patient care by analyzing the research literature on clinical procedures, medical devices, and drug therapies.
Gastroesophageal reflux disease (GERD) occurs when the lower esophageal sphincter (LES) malfunctions and allows acidic stomach contents to enter the esophagus. This can cause persistent symptoms, including heartburn, regurgitation, dysphagia, and belching. Left untreated, acid from GERD can damage the esophageal lining, forming strictures, and in some cases can lead to Barrett’s esophagus, which increases esophageal cancer risk.
Clinical practice guidelines from the American College of Gastroenterology indicate that GERD treatment depends on symptom severity and includes lifestyle modification and control of gastric secretion through medication (typically use of proton pump inhibitors) or, in persistent cases, minimally invasive endoscopic or surgical treatments.
The Linx Reflux Management System (Torax Medical, Shoreview, Minn.) is a relatively new minimally invasive laparoscopic surgery option for medically refractory GERD. It is a sphincter augmentation device consisting of a series of magnetic titanium beads connected on a stainless-steel cable. The device is intended to reduce the esophagus’s exposure to acid, improve symptoms, and reduce or eliminate the need for GERD medications. The beads are used to encircle the LES to reinforce the barrier, and magnetic attraction between the beads is intended to close the LES except when needed to allow swallowing of food and liquid. The beads are intended to separate during swallowing.
The evidence base for this technology consists of two prospective case series sponsored by the manufacturer and reporting on 144 patients (Ganz et al. 2013; Lipham et al. 2012). Interpretation of results is difficult because of deficiencies in the comparisons made, reporting of results, patient loss to follow-up, and post hoc analyses after one-year follow-up (for additional details, please download the full report). Outcomes were reported based only on the number of patients available at last follow-up (e.g., 116 of 144 enrolled patients at three-year follow-up, although patient numbers at follow-ups were sometimes unclear). The two available studies provided pre-post-treatment data on medical therapy versus Linx for some outcomes of interest.
The findings to 2 of our 4 key questions are as follows:
Key question 1: How does the Linx Reflux Management System compare with medical therapy for treating medically refractory GERD regarding esophageal pH, GERD symptom frequency and severity, GERD-related quality of life (QOL), medication use, and patient satisfaction?
Generally, because of the small evidence base and other quality factors (see above), the available evidence is insufficient to firmly conclude that device implantation resolves GERD symptoms, obviates the need for medication, or definitively improves QOL and patient satisfaction.
Ganz et al. (2013) reported data on an intent-to-treat basis for some outcomes of interest on 98 of 100 enrolled patients, as follows, at one year; 85 patients provided data at year 3.
GERD-health-related quality of life (HRQL): At year 3, some patients who received the Linx device reported improved HRQL scores, which rates symptoms on a scale of 0 (no symptoms) to 50 (incapacitated by GERD). Patients’ median baseline HRQL score of 11 had declined to a score of 2. The clinical significance of this change is not well defined.
Esophageal pH: No studies reported esophageal pH of patients while on PPI therapy at baseline compared with post-Linx esophageal pH. Esophageal pH measures acid reflux decline and primarily uses 24-hour pH monitoring. Thus, the impact on esophageal pH of Linx relative to medication could not be determined.
Medication use: No data on medication use after Linx relative to other surgical or endoscopic procedures are available. PPI medication use before and after Linx are available. Ganz et al. (2013) reported that at one year, a 50% reduction in medication use was observed in 93% (93/100; 95% confidence interval 86 to 97) of patients. Thus, while medication use declined in many patients, many still required medication, so one cannot conclude from these data that Linx obviates the need for GERD medication.
Key question 2: What adverse events (AEs) are reported in studies of the Linx Reflux Management System?
Ganz et al. 2013 and Lipham et al. 2012 reported AEs. Dysphagia was the most commonly reported AE, occurring in 88 of the 144 patients enrolled, although some patients were lost to follow-up in these studies. In most patients reporting dysphagia, the condition resolved within a few months. However, study authors reported that “serious AEs” occurred in eight patients: four cases of persistent dysphagia required device removal; one case of persistent vomiting requiring device removal; two cases requiring hospitalization from nausea and vomiting, but no device removal; and one case in which the patient experienced pain requiring hospitalization. One Manufacturer and User Device Facility Experience (MAUDE) database report from FDA’s AE database indicated that a Linx bead had migrated to inside a patient’s esophagus.
The Linx device has been commercially available in Europe since November 2008 and was granted FDA marketing approval in March 2012. According to the manufacturer, more than 1,000 Linx implants had been performed as of mid-2013, approximately half of which occurred in the United States.
Four studies are ongoing that are expected to be completed between 2013 and 2016, but none are controlled trials that compare the device with other treatments for medically refractory GERD; thus, questions of the device’s efficacy relative to other surgical or endoscopic treatments will not be answerable from the data generated by these studies.
State Of Evidence Base
Quantity of evidence: low
The evidence base consists of two prospective pre-post-treatment case series (Ganz et al. 2013, Lipham et al. 2012) reporting on 144 patients. These studies provided data on only some patient-oriented outcomes of interest (quality of life, patient satisfaction, medication use in patients before and after magnetic sphincter augmentation device implantation). No data on comparisons to other surgical or endoscopic GERD treatments were available. Given the large number of patients affected by medically refractory GERD and the need for comparative data on GERD treatment options, we consider the quantity of evidence to be low.
Quality of evidence: low
No well-designed controlled trials are available. The only available studies are pre-post-treatment studies sponsored by the manufacturer. Weaknesses of these studies include inconsistent and incomplete results reporting (Ganz et al. reported intent-to-treat [ITT] at one year, not at subsequent follow-ups, patients were lost to follow-up; Lipham reported findings on the basis of patients left at follow-up, not ITT), and post-hoc analyses on an unclear number of patients. Both studies took baseline esophageal pH level measurements while patients were off PPI therapy, so no pre-post pH comparison data for PPI therapy and Linx are available. Results in the text of articles did not consistently correspond to results in tables. See full report for further details.
Consistency of evidence: moderate
While studies did not provide data on treatment comparisons we believe to be important, for the outcomes they did report both studies reported similar pre-post outcomes and frequency of adverse events, including eight events they categorized as serious (six, Ganz et al.; two, Lipham et al.). For efficacy outcomes, too little or no evidence is available to assess consistency.
Excerpted with permission from ECRI Institute’s database of Emerging Technology Evidence Reports. To download the full report, visit www.ecri.org/managedcare.
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