Review for 10.1186/s12876-021-01961-9 (2021)

Title: Perianal Disease Onset Age is Associated with Distinct Disease Features and Need for
Intestinal Resection in Perianal Crohn’s Disease: A Ten-year Hospital-based Observational
Study in China
Version: 2 Date: 12 May 2021
Reviewer's report:
It is a retrospective mono-centric experience about perianal CD in a Chinese non pediatric
hospital, however many issues about the study methods exist:
-first of all: according to table 1 patients mean age at CD diagnosis in your so called “POP”
is 18 years and according to Montreal Classification age at CD<16 is the first age class (A1).
According to these facts to speak about pediatric patients seems not completely appropriate.
-evaluating the PCD diagnostic delay, even in the relationship with the age of onset of perianal
CD and abdominal CD, it seems that perianal CD always anticipates the abdominal CD
involvement, but all of us know that in the real life it is not the only nor the most frequent
situation, please clarify and better explain the patients selection criteria.
-M&M paragraph 2.1: “The follow-up period was calculated from the date of CD diagnosis to
the end of data collection” this seems the disease duration!? It is clear that in a retrospective
study they can coincide, as it is only arbitrarily decided, or conversely, do you mean that you
have you performed the diagnosis at your Center having scheduled outpatients charts starting
from the date of the diagnosis? Or maybe is it a single phone call based retrospective evaluation?.
This should be clarified.
-you seems to put together under the term PCD many different situations: fistulae/abscesses
but even hemorrhoids, ulcers and fissures: however the reported number of patients with these
objective findings summarized are more than the global number of 293 patients, indicating some
patient has been considered twice or more times because of associated findings. This should be
addressed, even because if perianal fistula and abscess are strongly related to CD, it is not for
hemorrhoids or anal fissures which have similar prevalence in the general population. At page
8 it is reported “Two hundred forty-six (83.1%) PCD patients achieved clinical remission of PD
after a certain treatment” which is the certain treatment? And which was the type of recurrence?
And what about the precise number of PSI?
-given the primary aim of the study, the perianal CD surgical treatment adopted and its
indications should be more extensively reported: worldwide the terms incision and drainage,
seton insertion, fistulectomy, de-functioning surgery (stoma, and which type?), and proctectomy
(how low?, total? with syncronous anastomosis?) are sometimes used improperly, a real specific
description of the adopted technique seems required to avoid misleading conclusions.
-in L3 patients the presence of luminal CD rectal involvement is not clear: to the purpose of the
study, this data is of primary interest and this should be reported and discussed.
-results sections line 5, 17.4% haemorrhoids, it seems a high percentage, which grade and which
associated surgical treatment was required?
-in this study the abdominal surgery for CD is postulated to be statistically related to the presence
of perianal disease (fistula/abscess). But which kind of abdominal surgical operations have been
performed as mean in your cohort (resections-strictureplasties-both, which tract of the bowel
treated, which the indications to surgery). Please clarify.
-indications to IFX therapy are not clear (to treat perianal disease previously undergone seton
positioning?, to control abdominal CD? in a prophylactic way?).
- in POP it seems that only 4 patients required abdominal surgery, 44 in AOP, but in table 1 it
is reported as “history”: what does it mean?
-what is this study really adding to the still available literature?, please discuss.
-conclusions seem not corroborated by the study protocol.