Summary Safety Review - Enterra Therapy System - Assessing the potential lack of effect

Review decision

A Summary Safety Review complements other safety related information to help Canadians make informed decisions about their use of health products. Each summary outlines what was assessed in Health Canada’s review, what was found and what action was taken by Health Canada, if any.


Issued: 2018-05-25

Product

Enterra Therapy System by Medtronic

Potential Safety Issue

Lack of effect

Key Messages

  • The Enterra Therapy System (Enterra) is a medical device licensed for sale in Canada. It is used to treat patients who have significant, long-term nausea, vomiting and abdominal pain due to problems with food moving through the stomach too slowly and where no signs of blockage exist (gastroparesis), and when medications have not helped. The device is placed inside the body to give electrical signals to the stomach wall.
  • Health Canada reviewed the potential lack of effect with the use of Enterra following international reports suggesting the device was not providing the expected health benefit to a large number of patients using it.
  • Health Canada's review of the available information concluded that certain patients with gastroparesis may not benefit from the use of this device even when it's working correctly. Effectiveness of medical devices can differ from patient to patient. This risk is outlined in the medical literature and in the device's Instructions for Use.
  • Health Canada will continue to monitor Enterra's safety and effectiveness, and will reassess these if new information becomes available.

Overview

Health Canada reviewed Enterra's potential lack of effect after receiving international reports suggesting the device may not work for certain patients with gastroparesis. Gastroparesis occurs in people with conditions such as diabetes, who have had stomach surgery, or who use certain drugs such as opioid pain relievers. It may also have an unknown cause.

The review focused on the lack of effect when the device was working properly, without any malfunctions. Enterra was determined to be not effective when the patient's symptoms and quality of life did not get better, or when results of tests continued to indicate abnormal stomach emptying after placement of the device.

Use in Canada

  • Enterra is a medical device licensed for sale in Canada to treat patients who have significant, long-term nausea and vomiting due to gastroparesis and when medications have not helped. The device is placed inside the body to give electrical signals to the stomach wall.
  • Enterra has:
    • a battery-powered generator placed under the skin near the stomach and connected to two wires that provide electric pulses to the stomach wall; and
    • a remote-controlled programmer to turn the generator on or off and to adjust its settings.
  • Enterra has been marketed in Canada since 2002

Safety Review Findings

  • At the time of the review, Health Canada had received 2 reports of complaints related to the use of Enterra. One reported nausea, vomiting, and abdominal pain many years after using the device. However, there was not enough information in the report to conclude that this was a result of the device's lack of effect. In the second report, a patient described feeling a shocking or jolting sensation from the device, with no mention of symptoms suggesting lack of efficacy.
  • A review of the medical literature found 1 large study1 of 1,587 international reports of problems with Enterra. Of these 1,587 reports, approximately 450 described a possible lack of effect with the device, as well as long-lasting or repeated symptoms. Nausea and vomiting were the most common complaints suggesting a possible lack of effect. The time from placement of device to the problem being reported had varied from weeks to years. However, there was not enough information in these reports to draw any definitive conclusions. In the remaining reports, problems were due to device malfunctions such as loose connections and battery issues.
  • Some published studies on Enterra reported some improvements in patient symptoms, mainly nausea and vomiting. However, these studies often had many potential weaknesses. For example, many of these studies did not have a direct comparison group of gastroparesis patients who did not use Enterra, or who received a different form of treatment. Some evidence in the medical literature suggest that patients with the best chance of benefiting from Enterra use are those who have gastroparesis linked to diabetes, have nausea or vomiting as their main digestive symptoms, and are not taking opioid pain medications. A possible lack of effect with Enterra is described in the current Instructions for Use of the device.
  • The severity of gastroparesis symptoms can change over time. Sometimes symptoms can improve or even completely disappear long after the start of the disease. This makes it difficult to study the true benefits of Enterra in patients over time.

Conclusions and actions

  • Health Canada's review of the available information concluded that certain patients with gastroparesis who are candidates for treatment with Enterra may not benefit from using this device. Effectiveness of medical devices can be different from patient to patient, and this risk is outlined in the medical literature and in the device's Instructions for Use.
  • Health Canada encourages consumers and healthcare professionals to report any adverse events related to the use of Enterra.
  • Health Canada will continue to monitor safety information involving Enterra, as it does for all health products on the Canadian market, to identify and assess potential harms.
  • Health Canada will take appropriate and timely action if any new health risks are identified.

Additional information

At the time of the review, Health Canada was not aware of any measures taken by international regulatory authorities (United States' Food and Drug Administration, United Kingdom's Medicines and Healthcare Products Regulatory Agency, and Australia's Therapeutic Goods Administration) on this issue.

The analysis that contributed to this safety review included scientific and medical literature, Canadian and international information, and what is known about the use of this device both in Canada and internationally.

For additional information, contact the Marketed Health Products Directorate.

References

  1. Bielefeldt K. Adverse events of gastric electrical stimulators recorded in the Manufacturer and User Device Experience (MAUDE) Registry. Auton Neurosci. 2017 Jan;202:40-44.

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