The Weight Loss Balloon: A Device Too Far?

This week, the media reported that “obese NHS patients are being given a gastric weight loss balloon”.

The balloon is placed inside a capsule and swallowed, then filled with water through a thin tube during a 15-minute consultation. An X-ray is conducted to confirm that it is in the correct position in the stomach and filled with water. After four months, a time-activated release valve opens, which allows the water-filled balloon to empty and pass through the gastrointestinal tract.

Two NHS patients have received this treatment at Musgrove Park Hospital. All the hype suggests it’s risk-free and a simple procedure, but can anything go wrong?

NICE says that the “evidence on the safety of the swallowable gastric balloon capsule for weight loss shows infrequent but potentially serious adverse events”. Yet the Guardian and the BBC made no mention of the problems

NICE reports: “The evidence of efficacy is adequate to support the use of this procedure provided that special arrangements are in place for clinical governance, consent and audit.”

Special arrangements mean “there are uncertainties about whether a procedure is safe or effective. NICE also recommend special arrangements if risks of serious harm are known”. Hmm, we didn’t see that either in the news.

The BBC trots out a consultant who says the pill offers “meaningful weight loss”. But no mention of the possible harms.

NICE evidence was updated in April 2020, including a meta-analysis, eight case series, and one case report.

The review included six studies, which were all prospective cohort studies – none were randomised. The meta-analysis reports total body weight loss after treatment (four to six months) of 12.8% (95% CI 11.6 to 13.9). Only two studies of 191 patients reported 12 months of weight loss of 10.9% (95% CI 5.0 to 16.9). Both these effects showed high study heterogeneity and should not have been pooled methodologically.

Serious complications occurred in about one in 200 patients and included gastric perforation and small bowel obstructions. Symptoms such as abdominal pain and nausea or vomiting were frequently reported and required management with medication.

The Daily Mail did make its readers aware of some of the problems:

Some had side-effects – 2.9% couldn’t tolerate it and needed it removed with an endoscope, but the authors said “serious adverse events were very rare”: these included three cases of small bowel obstruction, and one patient had a perforated stomach, all requiring surgery.

Readers of Trust the Evidence will be aware of our Deadly Device series on breast implants, the Essure Implant and transvaginal mesh, amongst others.

As it turns out, gastric balloon insertion has been around for some time as a strategy for managing weight loss. In June 2018, the FDA alerted healthcare providers about five more deaths associated with the use of liquid-filled intragastric balloon devices for obesity. The FDA said it was “carefully tracking adverse events, including a total of 12 deaths over the past two years, that have been reported in patients with two balloon devices used to treat obesity”.

These new capsule balloons avoid the surgery associated with previous devices, and no deaths have been reported.

We have previously written about ‘The Inevitable Harms of Weight Loss Drugs‘, whose history tells us it’s all too predictable. In the absence of randomised trials, a lack of long-term safety data beyond 12 months and serious adverse events in the observational data, we again think it may be all too predictable. However, without journalism criticising the evidence, the public might think balloons are the latest risk-free answer to their dietary woes.

Prof. Carl Heneghan is the Oxford Professor of Evidence Based Medicine and Dr. Tom Jefferson is an epidemiologist based in Rome who works with Professor Heneghan on the Cochrane Collaboration. This article was first published on their Substack, Trust The Evidence, which you can subscribe to here.