Sir, further to the paper by Brunton et al., I am writing to formally request that you issue an expression of concern and investigate the irregularities identified below.1

Firstly, I was surprised to see that the authors claim to conform to the STROBE statement despite the fact that STROBE (as the name implies) is for observational studies in epidemiology and this is an interventional clinical trial. One of the most important metrics for a trial to assess a device's acceptability and tolerability is patient flow. How many patients were approached but refused consent; how many were recruited but dropped out prior to treatment; and how many dropped out after? If this trial had been correctly identified as a trial by the authors and journal, and reported to the appropriate standard (CONSORT - with the 2016 extension for single arm and pilot trials), the prescribed flow diagram would have given us this information.

An unfortunate coincidence is that the number of patients reported appears irregular. The authors claim to have recruited seven patients, only one of whom dropped out due to reasons unrelated to the device. However, the plan when the trial began was to recruit ten patients. No explanation is given as to the deviation. Did the authors simply run out of money? Or was there some other reason to close recruitment at 70%? Concerningly, the history of changes to the trial registry (ANZCTR) is not reassuring. Despite the research group claiming to have only recruited seven patients publicly in your journal, they informed the registry on 12 December 2018 that they were closing recruitment as 'all 10 participants have been recruited'. What happened to the three mystery patients? Why were they not disclosed in the paper? Why did they pull out of the study (if indeed they did)?