Review for 10.1186/s12876-022-02282-1 (2022)

Title: Comparison of fully coated anti-reflux metal stenting and per-oral endoscopic myotomy
in patients with achalasia: a propensity score- matched retrospective study
Version: 5 Date: 27 Feb 2022
Reviewer:  Yusuke Fujiyoshi
Reviewer's report:
It was a pleasure to review the paper entitled Comparison of fully coated anti-reflux metal
stenting and per-oral endoscopic myotomy in patients with achalasia: a propensity score-
matched retrospective study by Yu-fen Tang et al.
This is a retrospective cohort study using a propensity score (PS) matching. Clinical efficacy
and complications of were compared between the POEM and fully coated anti-reflux metal stent
(FCARMS groups). By PS matching, 150 patients were enrolled (100 cases of FCARMS and
50 cases of POEM). FCARMS group has shorter operation time, shorter fasting time and lower
hospitalization costs than the POEM group. Repetitions of gastroscopy in the FCARMS group
was more often. The short-term effect (less than 6 mons) of FCARMS is similar to that of POEM,
the long-term effect (more than 2 years)#POEM is better than FCARMS.
I would like to praise the authors’ work on this paper and I found this paper is interesting in
comparing POEM with metal stent placement, which seems to be not the standard therapy for
achalasia. I have several remarks on this paper.
1. POEM is a surgical procedure while FCARMS is a stenting procedure, therefore the shorter
procedure time and the shorter fasting time are considered to be natural results. The low cost
of hospitalization is also a natural consequence of the short fasting time. In order to show the
clinical usefulness for achalasia in a clinical setting, isn't it necessary to compare the costs in
long-term follow-up?
2. Authors mentioned the stents require larger number of repeated endoscopies. If stents are
placed every few years when symptoms recur, it seems that the total cost of hospitalization and
treatment with FRARMS is higher than POEM. The clinical implication of this work and the
indication of FCARMS should be mentioned clearly in a more realistic way.
3. The remission rate of FRARMS group after 2 years is low at 60%, but achalasia is a benign
disease and refractory, so retreatment is likely to be necessary. According to the previous data,
the remission rate after 3 years is reported to be about 50%. I think the remission rate is expected
to decrease thereafter. In actual clinical situations, in what kind of patients are stents indicated?
4. POEM is a radical treatment, whereas stenting is a temporary treatment which is similar to
PBD or Botox injection. Is there any data to compare FRARMS and PBD or Botox injection?
5. Why did you remove the stent 3-7 days after deployment? Wouldn't it be better to leave it
in longer?
6. Is there a higher risk of stent migration in patients Ling classification subtype 3, which has
diverticulum?
7. Esophagogram Grade 3 with dilated esophagus was shown to have a lower remission rate in
FRARMS. Isn't it dangerous to deploy a stent in a dilated esophagus because of the increased
risk of migration?
8. Why are stents more effective in HRM Type 3 with spasm? Also, was the stent placed more
proximally than in other types?
9. Authors stated that POEM and stents are equally effective in HRM Type 3, but in POEM for
HRM Type 3, did you perform long myotomy to cut all the spasm?
10. Authors mentioned that stents can be reused, but do you actually store stents for several
years and then reimplant them a few years later? Is it safe to reuse them?
11. Authors mentioned that there was 10% bleeding with the FRARMS group. How much
bleeding was seen in these cases?