Review for 10.1186/s12876-019-1104-z (2019)

Reviewer’s report  
 
Title: Durability of pneumatic dilation monotherapy in treatment -naïve achalasia patients  
 
Version: 0 Date: 28 May 2019  
 
Reviewer: Pietro Familiari  
 
Reviewer's report:  
 
I read with interest the paper by Dr Javed and co -authors.  
The topic is not new. Pneumatic dilation is a relatively  old technique, but easy and reliable, and 
many studies about it have been published in the last decades. However, a lot of questions about 
the technical details of the procedures, the  indications, the number of dilation needed, the time 
interval between the dilations, the outcome remain still open.  Especially the durability of the 
effects of pneumatic dilation  is still debatable and well conducted studies on this topic are 
needed.  
 
In this paper authors reported on a series of treatment -naive achalasia  patients who underwent 
dilation, and tried to analyze the durability of the dilation procedure over time, the number of 
dilations needed and factors associated with clinical success and failure.  
 
If the topic and the aims of the study are really interest ing, unfortunately something in the 
methods seems to compromise the research.  
 
1) The major limit of the study is in the methods. It has something to do with the same 
definition of the procedure, success and failure.  
Authors did not completely outline whi ch was the indication to a second or third dilation, but 
apparently it was symptoms persistence and/or a recurrence after the first one. Furthermore, they 
do not clarify in which situation the second dilation should be considered as a pre -determined 
second  step of the dilation procedure, or a retreatment because of a clinical failure with 
symptoms recurrence.   
I try to explain myself. Authors stated that "Success was defined as symptom remission for 
greater than one year after pneumatic dilation". However some of the patients underwent the 
second dilation or the third more than 4 years after the first one…. (results, page 8, "the mean 
time interval between PDs…was 677 days…and 817.9 days between the 2nd and 3rd". This is 
quite controversial.  
One thing is a patient with  an incomplete symptoms relief within 6 months or one year after the 
first dilation, and who undergo an additional second or third dilation. Another thing is to re -dilate 
patients with a very late symptoms recurrence. In the fir st case, the second and third dilation can 
be considered  additional "sessions" of the dilation procedure. In the last case, the dilation is a 
retreatment after a failure. This definition is very important especially if the entire statistical 
analysis and the results of the paper are based on the comparison of patients who underwent a 
single dilation or multiple dilation.  
The proposed results are equivocal:  apparently, in this paper, none of the patients underwent a 
second dilation for a recurrence after treatment failure. At a certain point authors concluded that 
dilation was successful in 35 out of 40 patients who underwent a single PD. However this is not 
exactly true, because if I change a little my point of view, 83 patients were initially treated wit h a 
single dilation, and for 43 patients (at least) another dilation was considered a necessary 
treatment with a "..mean time interval between PDs in patients who underwent two PDs … [of] 
677.6 days (range 14 -2,335 days)". It means that the clinical effica cy of a single dilation is less 
than 50%. The same is for the third dilation…  
2) Authors could probably describe and analyze the study population differently. They 
have a very good material. Maybe PDx1 could be a group of patients "who obtained symptoms 
remission for greater than one year after a single dilation"; PDx2 could be a group of patients 
who obtained symptoms remission for greater than one year after 2 dilation sessions, performed 
within a 12 -month time interval"; PDx3 - a groups of patients who o btained symptom remission 
after 3 sessions of dilation, that performed  within a 12 -month time interval.  
If a patient underwent the second dilation after more than one year should be considered a 
clinical failure, not a patient of a PDx2 group. If you anal yze the data in this way probably the 
outcomes of the study will significantly different, but very interesting. (see results, page 8, 
dilation. "When comparing one PD to multiple PDs, there was no significant difference between 
the number of successes and the number of failures (p=0.06)").  
3) Why some patients with a clinical failure underwent surgery, instead of a second or 
third PD?Probably it should be explained  
4)  Authors should add a flowchart that describes the process of enrollment, and the 
treatmen t, how many patients had a clinical success after 1 dilation, how many required a second 
dilation within 1 year, how many had a lon term recurrence . It will make much more easy to 
understand the study,  
5) Results, page 7 -8 "Of the 103….between the second  and third PD".  
A total of 103 patients were included in the study. However, outcomes were calculated on 83 
patients with follow -up. However, authors calculated the number of procedures, age of patients, 
the time interval between a procedure and the other (…)on 103 patients. The clinical success and 
statistical analysis were done on 83 patients… Since the study design is retrospective, probably 
only the 83 patients with follow -up should be included. Of course, authors should mentions in 
the flow -chart (poin t 4) that N°patients had achalasia, Nn° were treatment -naïve and underwent 
PD, Nnn° patients had a follow -up and were included in the analysis… and so on  
6) How authors defined the clinical efficacy. Did they use Eckardt score? Did they use 
other scores?  
7) Do the authors have additional clinical information, including GER rate after 
pneumatic dilation?  
 
 
 
 
 
 
 
 
 
 
 
Are the methods appropriate and well described?  
If not, please specify what is required in your comments to the authors.  
 
No 
 
Does the work include the necessary controls?  
If not, please specify which controls are required in your comments to the authors.  
 
Unable to assess  
 
Are the conclusions drawn adequately supported by the data shown?  
If not, please explain in your comments to the authors.  
 
No 
 
Are you able to assess any statistics in the manuscript or would you recommend an  
additional statistical review?  
If an additional statistical review is recommended, please specify what aspects require further  
assessment in your comments to the editors.  
 
Not relevant to this manuscript  
 
Quality of written English  
Please indicate the quality of language in the manuscript:  
 
Acceptable  
 
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